Petroleum Development Oman L.L.C. - PDO - Hazardous... · Revision: 3 Effective: May-15 Petroleum Development Oman LLC Printed 10/05/15 PR-1045, Hazardous Substance Page 3 The controlled

Petroleum Development Oman L.L.C.

Hazardous Substances

Document ID PR-1045

Document Type Procedure

Security Restricted (Information Security Classification Definitions)

Discipline Well Engineering

Owner Wells Corporate Functional Discipline Head

Issue Date May 2015

Version Version No. 3

Link http://sww3.pdo.shell.om/Getdoc?Dataid=94969 (Intranet)

Keywords: Hazardous Substances, Acids, NORM, Explosives, Flammable Fluids, Safety Regulations, Personal Protective Equipment

This document is the property of Petroleum Development Oman, LLC. Neither the whole nor any part of this document may be disclosed to others or reproduced, stored in a retrieval system, or transmitted in any form by any means (electronic, mechanical, reprographic recording or otherwise) without prior written consent of the owner.

http://sww1.pdo.shell.om/dept/tsd/twm/TWB15/Information%20Security%20Classification%20-%20updated%20for%20PDO1.htm

http://sww3.pdo.shell.om/Getdoc?Dataid=94969

Petroleum Development Oman LLC

Revision: 3 Effective: May-15

Page 2 PR-1045, Hazardous Substance Printed 10/05/15

The controlled version of this CMF Document resides online in Livelink®. Printed copies are UNCONTROLLED.

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Revision: 3 Effective: May-15 Petroleum Development Oman LLC

Printed 10/05/15 PR-1045, Hazardous Substance Page 3


i Document Authorisation

Authorised For Issue: May 2015

Document Authorisation

Document Authority Document Custodian Document Controller

Tariq Al-Riyami (UWH)

Date:

Fuad Jalilov (UWZ/4)

Date:

Christian Koepchen (UWH/2)

Date:

ii Revision History

The following is a brief summary of the 4 most recent revisions to this document. Details of all revisions prior to these are held on file by the issuing department.

Note that changes made as part of Document Maintenance (correction of broken hyperlinks) will not be recorded in this Revision Table.

Revision No. Date Author/ Editor Changes/ Remarks

3 03.05.2015 Reviewed by: Fuad Jalilov, UWZ/4 and Christian Koepchen, UWH/2

consolidated the content of PR-1453, Hazardous Substances with PR-1045, Hazardous Substances (this document)

revised all references to existing PDO CMF documents and those to withdrawn procedures were referred to live documents.

Safe distance around the radioactive source was reviewed and the equation was replaced with radiation levels to be used as criteria for determining safe distance.

Table ‎2-1, Sources in Common Use in PDO was reviewed.

2 16/08/2004 I.K.Naamani, TWX/91

Checked by: Suhail Al-Riyami, TWX/6

1 08/12/2001 TWM/92 Initial Issue, post merger of Well Services & Well Engineering.

0 14/10/1998 TM Services – OTW/1

Initial Issue





PR-1453, Hazardous Substances (withdrawn as, with the publication of Rev. 3.0 of this document, PR-1453 content is combined with PR-1045, Hazardous Substances)

0 14/10/1998 TM Services – OTW/1

Initial Issue

1 08/12/2001 TWM/92 Initial Issue, post merger of Well Services & Well Engineering.

2 16/08/2004 Updated by: I.K.Naamani, TWX/91

Checked by: Suhail Al-Riyami, TWX/6

iii Related Business Processes

Code Business Process (EPBM V.4.0)

EP.63 Design, Drill, Modify, Service and Abandon Well

iv Related Corporate Management Frame Work (CMF) Documents

The related CMF Documents can be retrieved from the CMF Business Control Portal. Other, non-CMF documents and links to information relevant to Well Engineering can be found on the Well Engineering Documentation Page.

http://sww1.pdo.shell.om/dept_applications/Infrastucture/IMandT/TAXI/cmf/index.htm

http://sww.pdo.shell.om/sites/UWD/UWH/Lists/Well%20Engineering%20Documentations/Well%20Engineering%20Documentation%20%20New.aspx




TABLE OF CONTENTS

i Document Authorisation ......................................................................................................... 3

ii Revision History ..................................................................................................................... 3

iii Related Business Processes ................................................................................................. 4

iv Related Corporate Management Frame Work (CMF) Documents ........................................ 4

1 Introduction ............................................................................................................................ 6

1.1 Background ........................................................................................................................ 6

1.2 Scope ................................................................................................................................. 6

1.3 Purpose .............................................................................................................................. 6

1.4 Distribution/Target Audience .............................................................................................. 6

1.5 Review and Improvement ................................................................................................... 6

1.6 Step-out and Approval ........................................................................................................ 6

2 Procedure............................................................................................................................... 7

2.1.1 Flammable Fluids ........................................................................................................ 7

2.1.2 Stimulation Acids and Associated Chemicals ........................................................... 11

2.1.3 Disposal of Acid and Other Chemical Waste ............................................................ 17

2.1.4 High Pressure Leaks ................................................................................................. 18

2.1.5 High Temperature Wells ........................................................................................... 20

2.1.6 Explosive Devices ..................................................................................................... 22

2.1.7 Radioactive Devices .................................................................................................. 26

2.1.8 Naturally Occurring Radioactive Material (NORM) ................................................... 28

3 Hazards ................................................................................................................................ 30

4 Roles and Responsibilities ................................................................................................... 32

5 Appendices .......................................................................................................................... 34

5.1 Appendix 1, Forms and Reports ....................................................................................... 34

5.2 Appendix 2, Glossary of Terms, Abbreviations and Definitions ....................................... 34

5.3 Appendix 3, Related Business Control Documents and References ............................... 35

LIST OF TABLES

Table ‎2-1, Sources in Common Use in PDO .............................................................................. 26

Table ‎4-1, Roles and Responsibilities ......................................................................................... 32

Table ‎5-1, Glossary of Terms, Abbreviations and Definitions ..................................................... 34

Table ‎5-2, Related Business Control Documents and References ............................................ 35





1 Introduction

1.1 Background

Hazardous substances are often used or encountered in Well Services Operations. These chiefly include:

Flammable fluids used in stimulation, sand control and clean-up operations;

Acids used for well stimulation;

Cryogenic Nitrogen used for nitrogen lifting;

Explosive devices used for well perforating, tubular cutting, backing-off pipe and side wall sampling;

Radioactive sources used in well logging operations;

Naturally Occurring Radioactive Materials (NORM)

that may be encountered mainly as LSA scale on tubing, etc. retrieved from wells.

By definition, hazardous materials require the introduction of formal safety measures and precautions in order to minimize the risk of injury to personnel and damage to assets.

1.2 Scope

This Procedure is applicable to all Well Services operations conducted either by PDO or Contractor personnel on all production wells operated by PDO.

1.3 Purpose

This Procedure sets out the standards for Well Services operations conducted on PDO operated wells using hazardous substances. It forms the framework from which detailed work practice safety procedures can be developed and maintained by contractor companies who perform Well Services operations using hazardous substances on behalf of PDO. It should also be used as a reference document in conjunction with other specific Well Services Procedure, when compiling individual well programs.

1.4 Distribution/Target Audience

This Procedure document will be distributed to all PDO Section Heads who have interfaces with the Well Services Operations, all Well Services Supervisors and Contractor Supervisors. The document will also be available via the Livelink system on the PDO web site.

1.5 Review and Improvement

Any user of this document who wishes to provide constructive feedback, or who encounters a mistake or confusing entry is requested to immediately notify the Document Custodian.

This document shall be reviewed as necessary by the Document Custodian, but no less frequently than every four years. Triggers for full or partial review of this Specification are listed in PR-1444, Well Engineering and Logistics Management Framework in Chapter 5.2.4, Document Review.

1.6 Step-out and Approval

Step-Outs shall be managed as described in PR-1444, Well Engineering and Logistics Management Framework in Chapter 5.2.1, Variance from a Standard (Step-Out)

The Step-Out Request Form can be downloaded from here.

mailto:[email protected]?subject=PR-1045,%20Hazardous%20Substances

mailto:[email protected]?subject=PR-1045,%20Hazardous%20Substances








2 Procedure

2.1.1 Flammable Fluids

2.1.1.1 General

Flammable fluids are often pumped in well stimulation, sand control and clean-up operations. They present particular hazards due to the dangers of ignition and specific precautions are necessary to ensure such operations are carried out in a safe manner.

2.1.1.2 Classification of Flammable Fluids

Two physical measurements of flammable fluids are used to characterise their burning characteristics:

Flash Point: The lowest temperature at which a fluid will give off vapours sufficient to form a flammable mixture with air, which will flash across the surface when an ignition source is applied.

Note: The lower the flash point, the more hazardous the fluid.

Vapor Pressure: The tendency of a substance to vaporize - generally expressed in terms of absolute pressure at a particular temperature. A boiling liquid has a vapor pressure equal to atmospheric pressure at its boiling temperature. Reid Vapor Pressure (RVP) is the vapor pressure calculated at 100oF or 37.8oC.

Note: The higher the vapor pressure, the more hazardous the fluid.

For most pure flammable liquids and high flash point crude oils, the lower the flash point, the higher the vapour pressure. However, certain crudes and mixtures may exhibit a low flash point together with a low vapour pressure.

Fluids are classified as flammable if their flash point is below 100oF (37.8oC). This will include most crude oils, aromatics such as Xylene, Gasoline, distillates and condensates. Diesels and fuel oils are generally not considered as flammable but as combustible fluids.

2.1.1.3 Restrictions on Pumping Flammable Fluids

Flammable or fuming liquids shall never be pumped into open tanks near machinery or personnel. Highly volatile liquids (e.g. LPG, Gasoline, Benzene, Distillates, Condensates, etc.) shall only be pumped with specially designed and approved pumping equipment.

Aromatic Solvents (Toluene, Xylene, Acetone) and Alcohol shall not be used as fracturing fluids. They may be used as additives to fracturing fluids, and may also be used undiluted for purposes such as matrix stimulation, sand control or well bore clean-up jobs, provided that the following guidelines are followed:

i. They shall not be run through blender tubs, open-top mixers or open top displacement tanks in undiluted form.

ii. Transportation of such undiluted fluids shall be in drums or specially designed tankers.

Normally, only crude oil based mixtures having a vapor pressure of less than 7.5 kPa and a gravity of less than 50o API shall be used as fracturing fluids. Fluids with vapor pressures of up to 15 kPa may be used, if extra specific precautions are employed, but their utilization is strongly discouraged.

Such fluids are classified as "High Risk" and specific procedures regarding their use are given in the following sections.

Note: The only crude oil that is likely to fall within this high-risk grouping is Sayyala crude. All other Omani crudes would be considered as "Normal Risk" and may be used for fracturing without the extra precautions for high-risk fluids. Sayyala crude may be used for circulating purposes, i.e. displacing well contents.





All crude oil based fluids may be used for matrix stimulation, sand control and clean-up operations, provided that if they fall into the high-risk category (Sayyala crude) the above restrictions are applied.

As diesel is considered as a combustible, and not a flammable fluid, fracturing, clean up and other downhole pumping operations may be carried out without specific precautions, provided that no flammables are added to the fluid.

2.1.1.4 Mixing of Flammables

If alcohol is added to acid or water-based mixes and/or aromatics (e.g. Toluene, Xylene etc.) added to oil-based mixes, in order to enhance the clean-up properties of acidizing and fracturing fluids, special care must be taken when both mixing and transferring these fluids.

The proportion of volatile flammables shall be limited in order to prevent the resultant fluid becoming High Risk as defined above. Experience has shown that the following limits are effective:

The alcohol percentage of a water-based mixture shall be less than 40% by volume.

The aromatic solvent percentage of an oil-based mixture shall be less than 50% by volume.

At all times, the mixture shall be checked for vapor pressure and API gravity prior to use.

Where practical, mixing shall be performed in the contractor's yard prior to the job, in a safe and controlled manner. For small volumes, low speed paddle type mixers powered by a suitable zone 1 hazardous area classified electric motor, or hydraulic motor powered from a remote power pack, shall be used. For large volumes, or where it is otherwise necessary to mix fluids on location, the undiluted flammables and less volatile dilutent may be hooked to the suction side of the transfer, or pressurizing pump and pumped simultaneously, provided the following steps are taken:

the flammable fluid shall be connected to the pump suction via a connection that is between the dilutent source and the pump;

dilutent flow is started first and stopped last;

the flow of flammable fluid is metered and regulated so that the mixture is within the proportion limits given above;

the resultant mixture shall be placed in closed vented tanks. If it is necessary to use an open-top displacement tank to check volumes, this shall be placed a minimum of 10 meters from the pumping unit.

2.1.1.5 Specific Personnel Requirements for Pumping Flammables

All Stimulation Supervisors, Company or contractor, shall be fully trained in First Aid and be knowledgeable in the treatment for exposure to toxic and flammable liquids and vapors and the treatment of burns. All Stimulation Supervisors shall be specifically trained in the hygiene standards and environmental controls necessary when handling hazardous pollutants such as aromatics. All members of the stimulation crew shall be trained in basic fire fighting, with specific knowledge of the use of dry powder extinguishers in combating flammable liquid fires.

2.1.1.6 Equipment Set-up for Pumping Flammables

All pumping equipment shall be placed at a minimum of 15 meters from the wellhead.

All tanks shall be placed crosswind or downwind from the equipment and the wellhead.

Tanks used for gelling fluids or tanks into which fluids are circulated shall have the mixing (or load) line either extending down to the bottom of the tanks to prevent splashing or shall be directly bottom filled. A water tank shall be hooked up to the farthest upstream point of the suction line to permit flushing of the blender, pumps and lines prior to breaking out connections.




All tanks shall have effective shutoff valves. Leaking valves shall be temporarily rectified by installing a second valve on the downstream side. Tanks containing high-risk flammables shall be placed at a minimum of 50 meters away from the wellhead and surrounded by a ditch or bundwalls to contain any fluid spill and hold it away from the pumping equipment and wellhead. Connections between tanks and manifold shall be made using fixed rigid pipe not flexible pipes.

The blender (if required) shall be placed at a minimum distance of 10 metres from all tanks containing flammables, with its engine upwind of the blending equipment and shall be equipped as follows:

diesel engine equipped in accordance with SP-2037, Well Engineering Specification for the Use of Equipment in Hazardous Areas;

functioning remote readout densitometer;

sand flow control mechanism to permit unattended control of sand flow from the dump tank.

The stimulation pump truck shall be placed at a minimum distance of 10 meters from the blender and tanks. It shall be fitted with a diesel engine equipped in accordance with SP-2037 and a pump overpressure shutdown and/or pressure relief system.

The proppant truck (if required) shall be fitted with a proper spout to permit unattended sand discharge to the blender. It shall only be moved into position after fluid mixing has been completed.

Open-top displacement tanks on pumps or blenders shall not be used for flammables. If a displacement tank is required for flammable fluid measurement, it shall be separated from the blender and pump truck, by a distance of 10 meters. At no time shall high-risk fluids or undiluted volatile aromatics be placed in open-top tanks.

All connections between tanks, manifolds and blender/pumps and lines to wellhead shall be suitable for the fluids being pumped, of adequate pressure rating and fitted with hammer unions. Additionally:

All lines (suction, discharge and flow-back) shall be laid out in an orderly, accessible manner and shall in no circumstances pass under tanks, trucks or other service units.

All hoses and unions on both pump suction and discharge shall be covered with hose covers to deflect fluids in case of leaks.

All pressurized mobile flowlines shall conform to the requirements of PR-1454.

All discharge lines shall be fitted with a check valve at the ground manifold, the wellhead, or CTU inlet and each line shall have a positive shut-off valve as close to the wellhead as possible. A bleed-off valve and line shall also be fitted between each shut-off valve and the wellhead master valve.

Back-flow, bleed and release lines from the well or pumps shall be made of steel and laid to a specific discharge tank or pit, at a safe distance (minimum of 50 meters) from the wellhead and pumping equipment. All such lines shall be securely staked down with safety snubbing lines to prevent flailing.

Fluid pumping is known to create a static electric charge build-up that can be particularly hazardous when pumping or mixing flammable liquids. To prevent this build-up, all equipment (tanks, blenders, pumps, manifolds, proppant trucks) shall be adequately bonded together and earthed to the wellhead, in accordance with SP-2037, Well Engineering Specification for the Use of Equipment in Hazardous Areas.

All electric equipment and instrumentation associated with the stimulation operation shall conform to the requirements of SP-2037, Well Engineering Specification for the Use of Equipment in Hazardous Areas.

http://sww3.pdo.shell.om/livelink/livelink.exe?func=ll&objAction=download&objId=15918570










2.1.1.7 Fire Fighting Requirements for Pumping of Flammables

The Pumping of flammables obviously involves a greater risk of fire than normal well stimulation with acids. For this reason the spacing of equipment shall be such that the risk of propagation of fire is minimized.

The fighting of major fires, especially involving tanks holding flammable fluids are a specialized activity for purpose trained fire crews. Fire fighting by the stimulation crew shall be limited to the extinguishing of minor fires, or in the event of a more major fire, attempting to secure the well by shutting it in.

The following fire fighting equipment shall be available at the wellsite for all pumping operations involving flammables:

one 150 kg dry powder fire extinguisher trolley (filled with purple 'K' powder)

one 9-kg dry powder fire extinguisher located at each major vehicle positioned on the wellsite.

2.1.1.8 Safety Regulations for Pumping Flammables

For the purpose of these safety regulations pumping of flammables shall also include mixing, gelling, line priming, transfer pumping etc.

Pumping of flammables shall not commence or continue for long periods during the hours of darkness unless adequate lighting is available and specific authorization is obtained. Only in exceptional cases, and then only after approval by the Well Services Team Leader, shall 'High Risk" fluids be pumped in hours of darkness.

Operations shall not start during electric storms (i.e. lightning flashes). If lightning occurs whilst pumping is progress, the pumping shall be stopped as soon as it is safe to do so.

No other operations (rigging up or down, construction, welding etc.) shall take place concurrently on the wellsite with the pumping of flammables at any time, other than those directly related to the operation and authorized by a Permit to Work.

All non-essential motors and electrical equipment shall be shut down during pumping operations.

All non-essential personnel, as established by the Site Supervisor, shall move to a safe location during pumping of flammables.

A clearly visible warning sign shall be placed at the entrance of the location indicating that the pumping of flammables is taking place, that site access is restricted to authorized personnel and that smoking/naked flames are prohibited. Warning cones shall be placed across the entrance to prevent unauthorized access of vehicles.

Safety Data Sheets for all fluids being used in the operation shall be available at the wellsite, from the PDO Toxic Materials Manual. Stimulation Supervisors shall refer to these safety data sheets to determine what precautions or specific procedures are required in normal and emergency situations prior to the commencement of operations.

2.1.1.9 Operating Guidelines

Two well services supervisors shall be present during all operations involving High Risk flammables, one controlling the tank/blender area, the other (senior) controlling the pumps/wellhead area.

All pumps shall be primed and tested prior to starting pumping and at no time shall tank fluid levels be permitted to drop to a point at which the blender or pump could lose its prime.

Prior to commencing the pumping of flammables, all suction manifolds and lines shall be primed and pressure tested with water to 120% of the maximum possible tank head. All discharge lines shall be purged of air and tested with water to the pressure rating of the wellhead. Pressure testing shall include all standby equipment, as available.




Prior to pumping flammable fluids into a suspended well for circulation or stimulation, the flowline shall be reinstated and pressure tested to its pressure rating before the operation commences.

Prior to pumping flammables, the vapor pressure (VP) and API gravity at ambient conditions of the fluid shall be measured.

At no time shall flammable fluids be flowed back from the well to the pumping equipment or fluid storage tanks. All backflow shall be made to the dedicated pits or disposal tanks, in accordance with environmental constraints regarding the fluid being flowed.

Following the pumping of flammables, all suction hoses, manifolds, discharge lines, pumps and blenders shall be purged with water prior to breaking out and rigging down. Flammables and water purged shall be collected in a tanker truck for future safe disposal in accordance with PDO's Waste Management Manual.

If flammable fluids are circulated out of a well into the flowline, the well shall be produced for at least twice the flowline volume to displace the flowline contents. If the well does not produce, the flowline shall be purged with 1.5 times its volume of inhibited water using a pump truck, within 24 hours of the operation.

If a well is to be suspended after pumping flammable fluids for stimulation or circulation, the flowline shall be flushed with 1.5 times the volume of the flowline of inhibited water within 24 hours of completing the operation.

Personal protective clothing, eye protection and filter type respirators shall be worn when breaking out lines following the pumping of flammables, even when adequately purged.

2.1.1.10 Emergency Shutdown

In the event of discharge line failure, fire, or any other emergency, all pumping and blending operations shall be immediately stopped and all personnel evacuated from the well area to the designated assembly point, using the escape routes planned in the pre-job safety meeting.

The senior Stimulation Supervisor shall assess the situation, and if considered safe, direct designated personnel to close the well master valve and storage tank valves.

If it is considered safe to do so, designated personnel shall attempt to extinguish any fire, but the following precautions shall be observed:

The primary aim in immediate fire fighting by wellsite personnel is to secure the well only. Extinguishing equipment fires is a secondary aim, only to be considered if it is safe to do so and within the capabilities of personnel onsite and equipment available.

All personnel involved in controlling a fire or flammable spill shall be equipped with self-contained breathing apparatus and protective clothing.

No attempt shall be made to extinguish a fire until all tank valves have been closed and equipment has been shut down.

Whenever a closed tank or tanker is on fire or exposed to direct flames or intense heat, all personnel shall be immediately evacuated to a safe distance of at least 750 meters from the site. This large distance is essential so that personnel are out of the range of a Boiling Liquid Expanding Vapor Explosion (BLEVE). No attempt shall be made, under any circumstances, by untrained personnel to extinguish fires of this type.

2.1.2 Stimulation Acids and Associated Chemicals

2.1.2.1 General

Acids are regularly used in well stimulation operations to increase their productivity or injectivity, by dissolving carbonates, clay minerals and drilling mud residues. Acid treatments can be grouped into one of the following three categories:

1) Well bore clean up: Limited injection of acids to clean up the well bore and remove drilling-induced superficial formation damage.





2) Matrix acidization: Injection of larger volumes of acid at pressures below the formation fracture pressure, to dissolve clay and/or carbonate material from the pore space, thereby increasing permeability.

3) Fracture acidization: Large volumes of acid injected at above formation fracture pressure, combining the removal by dissolution of pore blocking material with artificially induced fractures, thereby altering flow geometry.

Reference should also be made to SP-1194, HSE Specification - Chemical Management.

2.1.2.2 Types of Acid Utilised in Stimulation

2.1.2.2.1 Hydrochloric Acid (HCl)

Hydrochloric acid is the most commonly used acid in well stimulation as it is highly effective in dissolving carbonates such as limestone and dolomite.

Its major drawback is that it is highly corrosive to tubulars and pumps, especially at high temperatures. These effects may be reduced by the use of suitable inhibitors, although this is more difficult at elevated temperatures (over 120°C).

Commonly, a 15% solution (by weight) of HCl in water is used for stimulation, although this concentration may be increased if suitably inhibited. At concentrations above 20%, HCl fumes, which are highly toxic and corrosive, will be freely released, even at lower concentrations, some fumes will still be present.

HCl is generally delivered to and stored in field acid plants at concentrations of about 32%. It is diluted and mixed with other chemicals in the acid plant to the precise "recipe" required for a particular treatment and transferred by tanker to the wellsite in prepared form. Wellsite handling of the acid mixture is therefore minimized.

2.1.2.2.2 Hydrofluoric Acid (HF)

Hydrofluoric acid is an extremely reactive and toxic acid that will rarely be encountered either by itself or in concentrated form in normal oilfield stimulation operations. It is normally utilized in low concentrations (1.5 -3%) in combination with dilute (7-15%) HCl. This mixture, often referred to using the trade name "Mud Acid", is normally used for well bore cleanup or stimulation of sandstone formations as HF has the ability to dissolve silica.

It is usually prepared in field acid plants by adding powdered Ammonium Bifluoride to dilute Hydrochloric Acid. The relative concentrations of the resultant acid mixture will depend upon the original concentration of HCl and the amount of Ammonium Bifluoride added.

Typically, a 15% HCl solution will yield a 3% HF + 12% HCl concentration but, with the addition of sufficient Ammonium Bifluoride, up to 6% HF can be obtained, with consequent reduction to 9% HCl. Stronger concentrations of HF are rarely used, as they would require mixing HF solution with HCl.

HF is not only highly reactive, causing acid burns, but also extremely toxic to the human organism, due to migration of Fluoride ions into the body, where they will react with Calcium in the tissue, bones, and body fluids. This can lead to irreversible and often fatal complications in severe cases and is one of the reasons why low concentrations of HF will, normally, only be encountered in field use. However, special precautions shall always be taken for operations involving the use of HF, even at low concentrations.

2.1.2.2.3 Organic Acids

Organic acids have the advantage over Mineral Acids (HCl and HF) by being less corrosive to metals and easier to inhibit, especially at elevated temperatures. They are, however, less effective in stimulation treatments. Two organic acids are used, Acetic acid and Formic acid.

Organic acids are weaker than Hydrochloric acid, however, they corrode more uniformly and with less pitting than Hydrochloric acid and effective inhibitors are available for high temperatures (up to 200°C). Organic acids are generally used if deep penetration of live acid in





the formation is required or if scale removal treatments are carried out in surface facilities. They are also used, alone or in combination with mineral acids, for high temperature stimulations.

2.1.2.3 HSE Requirements

2.1.2.3.1 Health Hazards

Stimulation treatment fluids may contain many different toxic chemicals, in addition to the basic acid solutions, which may be added in solid powder form or as liquids.

The hazards involved in the preparation of treatment fluids are:

Skin contact: corrosive action of acids and absorption through the skin of toxic chemicals.

Eye contact: from splashing of corrosive liquids or airborne dust.

Inhalation: of toxic/corrosion fumes or chemical dust.

Ingestion: of toxic/corrosion liquids or solids.

2.1.2.3.2 Protective Clothing Requirements

When sampling, handling or mixing concentrated acids (greater than 20%) or any fluids containing HF acid and during the process of adding Ammonium Bifluoride salt to HCl acid, the following protection equipment shall be worn:

PVC Slicker suit.

PVC gloves (with sufficient arm-length to overlap slicker suit arms).

Chemical resistant mono goggles.

Respiratory protection appropriate to the location of the work:

In confined spaces, full protection from organic vapor/acid gas/dust is required, either by air-supplied breathing apparatus (preferred solution) or filter respirator (with correct filter element).

In open air situations, toxic/corrosive vapor build-up is not a problem and respiratory protection will only be needed if handling chemical powders (dust protection) or chemicals giving off specifically toxic vapor or gases (e.g. Benzene).

When handling dilute acids (less than 20%) without HF and rigging up or breaking out equipment at the wellsite, protection shall be worn as above with the following exceptions:

A long PVC apron, as a substitute for the slicker suit.

When using tubulars that may have previously been exposed to H2S gas and have coatings of Iron Sulphide, contact with acid will release Hydrogen Sulphide and, therefore, suitable personal H2S monitors shall be worn, and self contained breathing apparatus (SCBA) shall be available at the wellsite.

Refer also to SP-1234, HSE Specification - Personal Protective Equipment

2.1.2.3.3 Wellsite Safety Equipment

A tanker (minimum 8000 liters) of fresh water, fitted with a low-pressure pump to assist gravity feed for emergency situations, shall be on location for all acid jobs.

A deluge shower or other effective means of flushing accidental spills from people shall be available on location and permanently connected to the emergency water supply (see above).

Eye washing facilities shall be available at the wellsite. In addition to an eyewash station allowing hands-free flushing of both eyes, portable eyewash bottles shall be located beside the pump truck, the acid tanker, and the monitoring/control station. Toxic Data Sheets, copied from the PDO Toxic Materials Manual, for all treatment fluids to be used, including acids and additives (such as inhibitors, surfactants, friction reducers etc.), shall be carried to the wellsite by the Well Services Supervisor. If any data sheet is not available (e.g. for new chemicals), it






shall be obtained from the Production. A sufficient quantity of neutralizing agents for treatment fluids (as required by the Toxic Data Sheets) shall be available at the wellsite to neutralize any spills. Sodium bicarbonate is recommended for HF, caustic soda for HCl.

Antidotes as specified in the Toxic Data Sheets shall be available on site, specifically if HF acid is present, 12 tubes of 25 gm Calcium Gluconate gel shall be carried for application on necrotic burns.

In addition to normal drinking water supplies available at the wellsite, 2 x 10 liter containers of potable water shall be available on the location for First Aid purposes.

Rubber gloves for First Aiders and strong scissors for cutting away clothing shall be available.

A mild liquid soap, which is useful to assist flushing/washing of skin following contact with acid mixes, shall also be available.

2.1.2.3.4 Personnel Requirements

All personnel present on the wellsite shall be made aware of the hazards of pumping toxic/corrosive mixtures and the procedures to be followed in emergencies, such as line rupture, personal contamination, etc.

At least two persons at the wellsite shall be fully qualified First Aiders, with particular knowledge of the procedures to follow in cases of eye or skin contact, swallowing or inhalation of the toxic/corrosive substances utilized in acid stimulations. The names of the designated First Aiders shall be displayed in the Contractor’s Frac van.

2.1.2.4 General Guidelines on Chemical/ Materials Handling

All containerized (sacked or drums) chemicals and materials that are to be pre-blended or mixed on the fly shall be stored in the area, which shall be roped off and designated as a no go area, close the blender and the frac tanks. On initial arrival on location all chemicals shall be stored away from the main site activity centers in a designated storage area as per the location plan. Visual inspection for handling or transportation damage shall be carried out jointly by the Site Supervisor and the Contractor Well Services Supervisor. All chemicals and materials shall be well marked and easily identifiable. Copies of the relevant toxic material data sheets shall be made available at the following locations:

in the frac van for easy access.

in the coffee shop

in the fluids testing lab

in the PDO site office

at the nearest PDO clinic or medical treatment centre.

It is the responsibility of the Contractor Well Services Supervisor to ensure that all his personnel are familiar with the data sheets. All chemical handling should be accomplished using the specified Personnel Protective Equipment. The pumping services contractor shall provide the necessary equipment required for the handling and mixing of toxic materials as per the recommendations of the material safety data sheets (i.e. overalls, eye guards, eye washers, emergency showers, rubber gloves, ear protectors).

2.1.2.5 General Guidelines for Materials / Waste Disposal

It is the responsibility of all staff on site to ensure that the location is maintained as per the PDO HSE standards which are stated in SP-1009, HSE Specification - Waste Management.

The overall philosophy is that minimal storage of waste materials will be done on site as there is limited security; therefore, all waste will be transported to the PDO waste sites (paper waste and scrap dump) at the earliest notice. Used containers (sacks/drums) should first be tallied to ensure stock control. The Contractor Site Supervisor shall order a PDO “box container” trailer from the location, to use for immediate storage and transportation to the waste sites.





Empty drums and containers shall be punctured in the mid or lower section, taking care not to spill residual contents of hazardous materials, in order to prevent removal and further use of the drums. The containers should then be moved to the waste collection area to await transport, which will normally be supplied by PDO, to the PDO waste dumpsites.


The following operating guidelines shall pertain specifically to acid stimulations.

Prior to rig-up, a toolbox meeting shall be held with all personnel at the wellsite. The following shall be discussed:

Locations of First Aid equipment, eyewash station, eyewash bottles, deluge shower etc.;

Details of Toxic/corrosive chemicals to be used on the job;

Special protective clothing to be worn;

Emergency responsibilities and action plan.

Telephone/radio communications contact with emergency services shall be available and contact confirmed prior to rigging up and prior to initiating any stimulation with toxic/corrosive fluids.

If HF acid is to be used, the local clinic and/or medical officer shall be contacted and advised to be on standby prior to the job and stood down upon completion of the job.

All lines shall be pressure tested with brackish water to the pressure rating of the wellhead and any joint that is even slight weeping shall be rectified, as any small acid leak may propagate rapidly to a full blown leak during the operation. If an acid leak is detected during the operation, all pressure shall be released from the line before the leak is investigated to prevent the possibility of an acid jet causing direct forceful contact with the skin.

Before breaking out any leaking joint, the lines shall be adequately flushed, internally and externally with water. Pumping of acids shall not take place during the hours of darkness unless adequate lighting is available and specific authorization is obtained from the Well Services Team Leader.

If corrosive fluids are circulated out of a well into the flowline, the well shall be produced for at least twice the flowline volume to displace the flowline contents. If the well does not produce, the flowline shall be purged with 1.5 times its volume of inhibited water using a pump truck, within 24 hours of the operation.

If a well does not flow or clean up after stimulation any corrosive fluid should be over displaced with 1.5 times the hole volume of inhibited brine into the reservoir within 24 hours of the operation.

2.1.2.7 Emergency Response

2.1.2.7.1 Personnel Contamination/Rescue

If workers become contaminated with toxic/corrosive fluids (e.g. due failure of a line/valve, human error, etc.), it is essential that they are thoroughly decontaminated and receive medical attention as soon as possible.

If the casualty is incapacitated (unconscious due to toxic fumes, knocked down by a blast etc.), it is possible that a rescue may be necessary. Prior to any rescue attempt the following steps shall be taken to protect all rescuers:

all pumping shall be shut down if it represents a hazard to rescuers;

rescuers ( minimum two) shall don all necessary protective clothing and use adequate respiratory protection;

In the case of toxic/corrosive fumes, a SCBA is recommended.





2.1.2.7.2 First Aid

As stimulation fluids are often complex mixtures of acids, surfactants, retardants, friction reducers, etc., it is generally difficult to be accurate in the choice of First Aid treatment to be administered.

The following are basic guidelines that may be generally applied for incidents involving the most common stimulation fluids. However, reference shall be made to the Toxic Data Sheets of ALL elements of the mixture and the first aid procedure modified as necessary:

At all times, clear details of the acid/chemical composition to which the victim has been exposed shall be forwarded with the victim to the clinic. This is especially important in cases of exposure to HF as special treatment may have to be administered immediately.

2.1.2.7.2.1 Skin Contact

Without waiting to remove clothing, the affected area should be flushed immediately with liberal quantities of water, whilst cutting away the clothing, using a deluge shower or low pressure hosepipe.

In cases of extreme exposure, immediate immersion in an open tank or bath of water may be effective for initial flushing. Flushing shall continue for up to 15 minutes and if there is no broken skin, mild liquid soap may be used to assist in removing some components of the contamination. Medical assistance shall be obtained as soon as possible. However, if it is necessary to transport the patient to the clinic, ensure that as much as possible of the toxic/corrosive fluid is removed before the patient is moved.

It is generally not advisable to utilize neutralizing agents directly on the victim without specialized knowledge except in the case of HF exposure where, after liberal flushing as before, Calcium Gluconate gel should be liberally applied and gently massaged into the affected area. It must be understood, however, that this gel itself does not neutralize the HF acid but only serves as a capturing agent for fluoride ions, which would otherwise penetrate the victim's body. Adequate flushing is, therefore, of primary importance to remove the acid.

2.1.2.7.2.2 Swallowing

Generally, in the case of swallowing any of the majority of stimulation fluids containing acids, inducing vomiting is not recommended. The victim should drink liberal quantities of water, or preferably milk, to dilute the contaminant. However, some additives such as certain specific inhibitors or surfactants may be highly toxic and induced vomiting is then advisable.

Reference shall, at all times, be made to the Toxic Data Sheets and vomiting shall only be induced in cases of ingestion of undiluted additives as advised. Wherever possible, vomiting should be induced by use of an agent such as IPECAC or, if this is not available, give the victim water to drink and stick a finger down the throat.

In all cases of swallowing medical assistance shall be obtained as soon as possible.

2.1.2.7.2.3 Inhalation

In all cases, the victim should be removed to fresh air and if breathing has ceased, artificial respiration shall be applied. Medical assistance shall be obtained as soon as possible.

2.1.2.7.2.4 Eye Contact

Flush the eye(s) immediately with fresh water or isotonic eyewash solution. No neutralizing agents shall be utilized. Obtain medical assistance as soon as possible.

2.1.2.8 Acid Spills

When spilt on the ground, stimulation acids will tend to be neutralized by reaction with the carbonates naturally present. However, the reaction may be violent and may also be accompanied by liberation of noxious and/or toxic fumes.

Care shall be taken when approaching such spills by wearing full protective clothing and, if necessary, SCBA.




The basic procedure to follow in all cases of spills is to:

Minimize the volume of the spill, if possible, by shutting off the source and minimize area of contamination by containment. Generally high-risk areas such as acid plants or storage tanks are equipped with bundwalls for this purpose.

Neutralize the spill by the addition of Soda Ash or caustic soda, or for HF use Sodium Bicarbonate whilst adding excess water, if neutralization is not effected by reaction with the ground.

Dilute with water provided this will not cause excessive spreading of the contaminant, especially towards equipment or personnel.

Report the spillage as per PR-1418, Incident Notification, Reporting and Follow-up Procedure Part 1

2.1.2.9 Spillage of Other Chemicals

Certain other chemicals, in liquid or solid form, may present long term hazards to personnel and/or the environment if spilt and, in all cases, appropriate action shall be taken, following the guidelines in the relevant Toxic Data Sheets.

2.1.3 Disposal of Acid and Other Chemical Waste

Acid and other chemical waste shall be reported and disposed of in accordance with PR-1084, Leak / Spill Management, Site Clean-Up and Restoration.

2.1.3.1 Cryogenic Nitrogen

2.1.3.1.1 General

Nitrogen at atmospheric temperature and pressure is a clear, odorless and colorless gas that liquefies at minus 195.8°C. Liquids at very low temperatures (i.e. less than minus 120°C) are normally referred to as cryogenic liquids.

Cryogenic Nitrogen is used in the oil industry as a compact source of high-energy inactive gas. One volume of liquid Nitrogen at its boiling point (-195°C) will produce 696 volumes of gas at ambient temperature (21°C) when maintained at atmospheric pressure. However, if the volume of the Nitrogen is contained, extremely high pressures can result when it evaporates with increase in temperature.

Although the gas itself is inactive, the use of Nitrogen in Well Service Operations poses three principal associated hazards:

extremely low temperature of the liquid Nitrogen;

extremely high energy of the expanding gaseous Nitrogen; and

possible asphyxiation due to the displacement of atmospheric Oxygen.

2.1.3.1.2 HSE Requirements

2.1.3.1.2.1 Personal Protective Clothing

Contact with liquid or low temperature gaseous Nitrogen will produce a rapid freezing of the skin and tissues, similar in effect to a severe burn.

If the duration of contact and area exposed are more than minimal, the damage may be permanent resulting in loss of affected limbs or organs. Eyes are particularly prone to permanent damage.

Contact with metal chilled by low temperature Nitrogen will cause immediate adhesion of skin and the portion of stuck skin may be torn off if the hand is pulled away abruptly.

In order to prevent these injuries the following protective clothing shall be worn at all times when working in close proximity to low temperature Nitrogen:









Eye protection in the form of goggles; the addition of a complete face shield is preferred;

Long sleeved coveralls, with legs worn outside boots;

Thick insulated gloves.


Asphyxiation

Normally the air we breathe contains about 21% oxygen. If the oxygen content falls:

below 15% - people suffer increased pulse, deeper and faster respiration rates and a decrease in coordination.

below 12% - people experience giddiness, judgement becomes poor and fingernails become blue.

below 10% - consciousness will be lost; and

below 8% - death may result.

One breath of pure Nitrogen can result in unconsciousness.

In well servicing applications, Nitrogen equipment is generally used in the open air, and the hazards of asphyxia are not great. However, cool Nitrogen vapor is heavier than air, and can accumulate in low lying areas and enclosed areas such as well cellars.

Care must always be exercised especially where large quantities of Nitrogen have been vented.

2.1.3.1.2.2 First Aid Treatment

If cryogenic Nitrogen does contact skin or eyes, it should be immediately flushed with large quantities of water before attempting to remove clothing as frozen tissue may come away with the clothing frozen to it.

Water temperature for flushing should be close to body temperature (40°C) and not above 45°C. Generally, in Oman water at ambient temperature is adequate.

Friction (rubbing) should never be used to warm affected areas, as tissue damage will result and dry heat: heaters, lamps, etc should also never be used.

Frozen tissues, which will appear waxy with a possible yellowish color, will be painless when frozen but extremely painful when thawed. Rapid thawing will aggravate the effects.

If exposure is massive, such that the general body temperature is depressed, total immersion in a warm (40 - 44°C) bath should be used to gently raise the body temperature and treatment for shock applied.

Energy giving food and warm (not hot) drinks may be administered to conscious patients, but alcohol or smoking must be prohibited, as these will decrease blood flow to the affected tissues.

Evacuation to hospital shall be made at the earliest moment.

First aid treatment for cases of asphyxia generally consists of removal to fresh atmosphere, artificial respiration or administering of Oxygen as necessary.

2.1.4 High Pressure Leaks

High-pressure leaks may not be visible near the line, however, a plume of dust and vapor may appear some distance from the line where the gas velocity is reduced and this will usually be accompanied by a loud whistling or screaming sound from the leak.

No attempt should be made to find the leak by looking closely or by running a hand over a line while it is under pressure. A small high pressure stream of gas can destroy an eye, cut off a finger or inject itself into a hand or arm with enough force to destroy internal tissues leading to eventual loss due to infection or reduction of blood circulation.





No attempt shall be made to approach suspected high-pressure leaks. The general area of a HP leak shall be identified from a safe distance and all pressure bled down prior to detailed investigation and repair of leaks.

2.1.4.1 Formation of Liquid Air

The extreme cold surfaces of metal in contact with cryogenic Nitrogen may cause condensation of gases in the air.

Frost will form on the surface and liquid will drip off into the drip pans or on the ground.

The liquid will contain a much higher percentage of oxygen (up to about 52%) than the normal atmospheric concentration, as its condensation temperature is higher than that of Nitrogen.

This high percentage of oxygen will cause the fluid to react like pure liquid oxygen and it may cause hydrocarbons such as diesel fuel, hydraulic oil, lubricating oil and grease to ignite spontaneously. It will also cause existing fires to burn faster and hotter.

Liquid air does not accumulate in large quantities and it will evaporate rapidly, but care shall be taken to keep any source of ignition such as cigarettes, matches, catalytic converters, open exhausts, etc. away from these areas.

Boots with metal nails shall not be worn, in order to prevent sparking.

Similarly, adequate earthing and bonding of equipment is required to prevent build up of static electricity.

2.1.4.2 Material Requirements

Many commonly used materials are unsuitable for use with cryogenic Nitrogen, especially carbon and low alloy steels, natural or synthetic rubber and most plastics that will become brittle. Suitable materials, which do not lose their strength or elasticity, are 300 series stainless steels, high nickel steels, copper and copper alloys, aluminum, Teflon compounds, asbestos and wood. All equipment in contact with cryogenic Nitrogen must be manufactured of such suitable materials to prevent failure. Special care should be taken when using seals other than metal to metal.

2.1.4.3 Pressure Relief

Excessive pressure may build up in closed systems due to the vaporization of liquid Nitrogen, therefore, all parts of the system, including the Nitrogen tanks, low and high pressure lines and chambers, shall be fitted with adequate pressure relief valves.

2.1.4.4 Stored Energy - Gas Filled Lines

The stored energy of a pressurized gas-filled system is very much greater than when liquid filled to the same pressure, therefore greater precautions must be taken for gas-filled systems:

Discharge manifolds and lines shall be suitably pressure rated, fit for purpose, and shall always be staked and/or tied down.

Non-essential personnel shall stay away from discharge manifolds and high pressure lines during operation.

No attempt shall be made to repair a leak by tightening connections until the line has been completely depressurized.

Pressure shall be vented from flowlines as soon as possible after the job is shut down.


The following operating guidelines shall pertain specifically to operations involving the use of cryogenic nitrogen.





The recommended personal protective safety clothing shall be worn at all times when working in proximity to low temperature nitrogen.

Liquid Nitrogen shall always be kept away from non-cryogenic materials.

Drip pans and areas under liquid Nitrogen piping shall be kept free from all flammable liquids (hydrocarbons, etc.) or solids.

Smoking materials and other possible sources of ignition shall not be brought to the work area.

Nitrogen units shall be placed at a minimum distance of 50 meters upwind or crosswind from the wellhead, other pumping equipment and tanks when pumping flammables.

Sufficient Chicksan swivels shall be placed in all high pressure Nitrogen lines to prevent line stresses when pressurized.

The Nitrogen line shall generally be tied into the fluid line by means of a T-connection close to the wellhead or CTU. A bleed-off valve and check-valve shall at all times be placed in the Nitrogen line and another valve and check valve between the T-connection and the treatment fluid pump unit.

No persons, other than those designated to operate valves, shall approach the Nitrogen lines during pressure testing or Nitrogen pumping.

Treatment liquid pumping shall commence before opening the valve to the Nitrogen pumps, unless the job procedure dictates otherwise. This will ensure that the lines are filled and will help prevent gas locking the fluid pumps.

The valve between the Nitrogen lines and the fluid pumps shall always be closed whenever the fluid pumps are shut down and gas is in the line.

The Nitrogen pump shall be shut down just before the end of the job. This will allow the Nitrogen to be flushed from the treating lines and will make the subsequent pressure bleed off safer and easier.

In operations where Nitrogen pumping is performed directly after fluid pumping, the fluid lines in the vicinity of any pressurized Nitrogen lines or valves shall not be broken out until all pressure is bled down from the Nitrogen lines.

High-pressure lines shall be vented as soon as possible after Nitrogen pumping has been shut down.

Personnel shall keep well away from vents and suspected leaks and no person shall ever attempt to tighten a leaking connection until the line pressure has been completely vented.

Personnel shall not enter a fog at ground level close to the Nitrogen unit, as this may contain a high concentration of Nitrogen.

Self-Contained Breathing Apparatus (SCBA) shall be used when working in, or entering for the purposes of rescuing personnel, an area with high Nitrogen content.

Ear protection shall be worn when close to venting Nitrogen lines or an operating a Nitrogen pumping unit.

2.1.5 High Temperature Wells

2.1.5.1 General

Steam Injection wells pose problems for operators due to the high temperatures involved (between 500 – 600° F). This can result in either scalding or burns due to accidental or unprotected exposure.

In Well Services operations, it is considered that wireline operations expose the crew to the highest risks and therefore specific precautions should be exercised.




2.1.5.2 HSE Requirements

2.1.5.2.1 First Aid Equipment

A First Aid kit that includes burn treating ointment and cold water shall be on site during operations on steam injection wells.

2.1.5.2.2 Personal Protective Equipment

The following PPE shall be available on site:

leather gloves (welder’s type);

safety glasses;

appropriate headgear equipped with full face clear visors;

Chemical resistant aprons.

This shall be worn, as appropriate, by personnel working:

in close proximity to the wellhead;

on wireline pressure control equipment whilst rigged up on the wellhead, especially if blowing down wireline lubricators;

handling wireline toolstrings and equipment retrieved from downhole.


2.1.5.3 Operational Considerations

Before entering the well site, the wellhead shall be checked for leaks and if leaks are found, the job shall be abandoned, the crew shall leave the location in an upwind direction and Wellhead Maintenance shall be informed.

Whilst working on steam injection wells, the entrance to the location shall be closed by red traffic cones and suitable hazard warning signs erected.

Prior to the commencement of operations, the safety precautions (as following), specific to working on high temperature wells, and the first aid treatment for burns and scalds shall be discussed in detail at the safety toolbox meeting.

When rigging up, the equipment should be spotted upwind of the wellhead to avoid any escaping steam during bleed off. The crane boom should be extended as far as possible, within load constraints, in order to increase the distance from the well.

Provisions shall be made, e.g. work platform, such that crewmembers do not need to climb onto or hold on to the Xmas tree whilst rigging up/down the lubricator equipment.

Extreme care shall be exercised when removing the well tree cap and operating the Xmas tree valves – appropriate PPE shall be worn.

Bleeding off pressure from the lubricator shall be done in a direction that is away from personnel and equipment.

All hoses connected to the wireline pressure control equipment and weight indicator shall be tied off to a remote fixture to prevent them contacting the Xmas tree and burning.

The toolstring shall be moved away from the wellhead whilst lowering so that personnel do not have to work in close proximity to the well head thus reducing the risk from burns.

Personnel shall keep clear of the BOPs to avoid contact with possible weeping of hot hydraulic fluid due to heat expansion.

Similarly the operator shall leave valves on the console in the open position to accommodate the expansion of the hydraulic fluid due to the excessive heat.






2.1.6 Explosive Devices

2.1.6.1 General

Explosives are used in various downhole operations including perforation of casing, cutting of tubulars, backing off pipe and side wall sampling.

Explosives perforating guns or other tools containing explosives are usually run on electric wireline or in the case of tubing conveyed perforators (TCPs) on tubing.

The explosives used for perforating are a series of shaped charges fitted into a carrier and are detonated by prima cord which itself is triggered by a booster charge and an electrically fired detonator. Tubing conveyed perforators can also be fired mechanically.

Under normal ambient conditions the explosives and prima cord are stable and can only be detonated by an explosive detonator. Detonators themselves, however, are sensitive and must be handled with great care.

SP-1216, WE Specification for Explosives

2.1.6.2 Site Storage

An area shall be designated as a storage area for the duration of the operation. This area will be a minimum of 15 meters from the wellhead and be able to allow the explosives engineer ample room to connect/ arm the downhole guns.

The area should also be barriered with only authorized personnel admitted. The key to the explosives container or truck-mounted container should be left with the PDO supervisor if for any reason the explosives engineer is off site. If at all possible the explosives container should be such that it can be easily removed from the site should a well incident occur, truck mounted preferably.

A manifest should be given to the PDO supervisor, ad displayed prominently, when the explosives reach the location and updated as the explosives are used.


The loading and unloading of secondary high explosives (shaped charges, detonators) in perforating guns, or other explosive devices, shall only be performed by contractor personnel who are trained and licensed in these operations.

The arming of any explosive device, with a primary high explosive detonator, shall only be performed by the Contractor Wireline Engineer and only immediately prior to introducing the device into the well.

Make-up and arming of explosives devices shall be performed in a designated area, surrounded by a red and white taped barrier, with signs stating "Explosives - No smoking - Keep Out"

Under no circumstances shall explosive devices fitted with primary high explosives be stored, even temporarily, at the wellsite. If any delay in the program requires cessation of operations after guns have been armed, or a miss fire they shall be immediately disarmed by the contractor wireline engineer prior to storage or transportation.

Electrically initiated detonators are extremely sensitive to electrical energy, both in the form of stray currents and/or direct electromagnetic radiation which may emanate from sources such as:

Incorrectly earthed electrical generators;

Impressed current cathodic protection systems;

Welding Equipment;

Radio transmissions;

Static charge build-up in the rig structure.





All non-essential electricity supplies and equipment that may cause stray currents shall be turned off during perforating operations.

Similarly, no operation with electrically detonated explosive devices shall be initiated during, or when threatened by electric storms or dust storms.

All DC generators, including the generator of the logging unit, shall be stopped before the electrical detonators are connected to the guns until the guns are more than 150 meters below surface. AC rig/hoist generators may be kept operating if required for lighting and safety systems.

Electric Arc Welding can cause unacceptable voltage differences between different parts of a connected circuit, or even create dangerous EM radiation levels. Therefore, all arc welding shall be stopped before electrical detonators are connected to guns and remain shut down until the guns are fired and inspected on surface.

Faulty equipment wiring has been known to set off guns at surface. Therefore, the location wiring (if any) shall be checked for damaged insulation, loose wires, hanging cables and the inadequate earthing of electrical equipment.

Although it is considered that personnel are safe from the hazard when the explosives are at the 150-metre level, this should not imply free use of radio transmitters, welding machines, cranes etc., as the potential hazard of detonation and damage to the wellbore still remains.

All radio transmissions in the vicinity of the operation shall be suspended for the duration of the operation.

All casing cathodic protection devices shall be switched off for the duration of the operation both on the well being worked on and any other well within a radius of 500 meters.

Prior to initiating any operation with electrically detonated explosive devices the Contractor Wireline Engineer shall monitor the voltage between major site equipment, i.e. WPH, and wellhead (casing) to verify that stray currents have been eliminated.

The maximum permissible voltage difference, without direct grounding straps between casing and rig, is 0.25 V. If a voltage greater than this exists, it shall be eliminated prior to continuing the operation even if this requires shutting down generators and lighting, which will preclude operating at night.

After the voltage difference has been proven to be acceptable, earthing straps shall be connected between the wellhead, WPH and the logging truck (see also SP-2037).

All personnel not directly involved in the operation shall be excluded from the area of the operation, and remain at a safe distance (50 meters for land operations).

Operation with explosive devices in hours of darkness shall be avoided as much as possible, and then shall only be performed when adequate, safe, lighting is available, which will normally exclude all such operations using a contractor's mast at night.

Perforating in underbalanced conditions or in any well requiring pressure control equipment shall be avoided during hours of darkness due to the possibility of not detecting a broken strand in the wireline and the subsequent dangers. This shall only be allowed when adequate, safe lighting of the entire working area, including the pressure control head and lubricator, is available.

It is not recommended to expose unprotected explosive devices (e.g. Enerjet guns, explosive and chemical cutters, back-off shots, etc.) to pressure shocks as could be generated during pressure testing of wireline lubricators.

In these cases, the pressure test shall be conducted before the introduction of these tools into the lubricator and a leak test conducted with the tools in the lubricator by slowly pressurizing the pressure control assembly to the expected CITHP and observing for leaks at the quick union.

Warning signs shall be placed on all access roads and any other roads passing the well within a distance of 200 meters advising that operations with explosives are in progress and that all radio transmitters shall be shut down.





A guard should be placed at the entrance to the wellsite to police compliance with the above, to direct all arriving vehicles to a safe area and to instruct all personnel to report to the Designated Responsible Supervisor directly.

2.1.6.4 Radio Silence Guidelines

Radio transmitters emit electromagnetic energy that could be sufficient to cause detonation of an electrical explosive detonator (EED). The magnitude of the hazard depends on a number of factors:

frequency and power of transmitter;

type of transmitter antenna;

distance from the EED;

configuration of the EED (e.g. legs open, grounded, connected to logging cable);

type of EED (i.e. RF filters, safety resistors etc.).

Basic guidelines have been formulated and agreed between PDO and contractors to ensure safe operations when electrically initiated explosive devices are utilised for well operations, which are:

applicable to wet-connect or battery-initiated TCP guns, wireline perforating guns, bridge plug and packer operations, sidewall core guns (CST only - not rotary coring tools), explosive back-off (string shot) and explosive or chemical cutters.

not applicable to percussion-initiated detonators as used in drop-bar or pressure fired TCP guns.

The contractor shall minimize the risk by using, whenever possible, electrical explosive detonators containing 50 ohm safety resistors and having a "no fire power" of 2 watts, which are available for all perforating guns.

All VHF and HF mobile radios shall be rendered inoperative or excluded from a radius of 200 meters from the rig and signs shall be placed on all fixed radios advising that radio silence is in progress.

PDO Telecommunications Department shall be informed of any operation with electrically initiated explosives about to take place within one kilometer of the following main camps, Lekhwair, Fahud, Yibal, Qarn Alam, Bahja, Rima, Nimr, Marmul, all of which have HF and VHF radio stations that may create a hazard.

Telecommunications Department shall also informed of any operation with electrically initiated explosives about to take place within 500 meters of the following telecommunications towers, all of which have VHF mobile radio base stations that may create a hazard to operations in the immediate vicinity:

Jebel Nahada 57EO9 22N16

Jebel Fahud 56E28 21N51

Lekhwair 55E19 22N50

Qarn Alam 57EO6 21N18

Sahma (Pump Station)

56E14 2ON24

Haima 56E15 19N57

Hubara (Pump Station)

55E59 19EO5

Hidab (above Marmul)

5E17 18EO7




Hand-held VHF (900 MHz) portable radios links (up to about 5) may be left in operation provided that the total sum power of all of these does not exceed 10 Watts. No such radio is to be operated within a distance of 10 meters from the area of operations with the explosive device (including catwalk and derrick).

Radio Silence shall be initiated prior to any work with EEDs and continue in force until the device has been brought to the surface, inspected and/or disarmed.

If the task is delayed or is of a protracted nature and there is an urgent or emergency requirement to break radio silence, a limited temporary relaxation of some of the radio shutdown requirements shall be permitted, provided that:

the detonators are more than 150 meters below the surface;

there is prior agreement between the Designated Responsible Supervisor, the Logging Engineer and the WSOE (if present);

the Logging Engineer halts the operations;

it shall be restricted to the use of certain radios under strict control; and

operations shall not be resumed until the radio has been switched off and radio silence resumed.

During extended perforating operations, radio shutdown may be interrupted after a complete gun has been fired. Under these circumstances the gun shall remain at the last perforating depth until the urgent transmission has ended, the transmitter has been switched off and radio shutdown resumed.





2.1.7 Radioactive Devices

2.1.7.1 General

Ionizing radioactive sources are used in well logging operations. In the majority cases these are normally sealed sources which are run in cased hole wells using a well pulling hoist or contractor’s rig.

The storage, transport and use of radioactive sources is governed by local regulations enforced by appropriate legislation and is strictly controlled in PDO under the following:

SP-1237, HSE Specification - Ionising Radiation

2.1.7.2 Sources in Common Use in PDO

Table ‎2-1, Sources in Common Use in PDO

2.1.7.3 General Operating Guidelines

Whilst on the wellsite, sealed radioactive sources shall only be removed from their transport shield and manipulated by the Contractor Logging Engineer (transfer of sources from shield to tool and vice-versa).

Transport shields containing sealed radioactive sources shall only be handled by the contractor radiological workers.

All contractors’ logging personnel on the wellsite shall be equipped with suitable personal radiation dosimeters.

Controlled areas, fenced off with red and white chequered tape with suitable warning signs erected, shall be set up surrounding the work area at a distance of at least 3 m from all hazardous operations.

If at all possible the container should be such that it can be easily removed from the site should a well incident occur, truck mounted preferably.

Access to these areas shall be limited to contractor personnel, except when operations are conducted using a well pulling hoist (WPH), when a designated person may remain for well control purposes during logging operations, if considered necessary.

Access to the areas above and, in particular, below the WPH floor shall be strictly limited to contractor personnel whilst radioactive sources on the floor. This is because sources are often mounted sequentially in tool strings and it is possible that high count rates may be present above or below the floor during such operations.





The designated person on the WPH floor for well control purposes, shall remain as far as possible from the sources of ionising radiation during the rigging up or down of logging tools and contractor personnel shall endeavour to direct any directional sources of Ionising radiation away from this person.

The logging contractor shall have suitable radiation monitoring devices (i.e. personal cumulative dosimeters, alpha, gamma and Neutron meters) available to handle any emergency situation beyond normal operations (e.g. loss of source, source stuck in tool, radiation contamination, etc.). Such monitoring devices shall be regularly calibrated to ensure their accuracy.

2.1.7.4 Temporary Storage of Logging Sources at the Wellsite

All logging trucks shall be fitted with designated source storage compartments that shall be considered as the primary storage location for radioactive sources at the wellsite. Sources shall normally remain within these compartments.

If the radiation level inside the logging cabin exceeds 2.5 µSv/hr whilst the logging cabin is occupied, the sources shall be removed from the truck's storage compartment to a suitable designated area on the wellsite, which is:

at a minimum distance of 15 meters from the wellhead;

situated apart from all normal work areas, accommodation areas and areas used by vehicles.

visible from either the logging truck or the WPH supervisor's office.

The temporary storage area shall be surrounded by red and white chequered tape with suitable warning signs erected designating it a controlled area.

Controlled area barricade and signal starts at a point where a 7,5 µSv/hr radiation level is detected. This distance shall be at least 3 meters.

A Supervised area barricade and signal start at a point where a 2,5 µSv/hr radiation level is detected.

2.1.7.5 Transfer of Logging Source between Carrying Shield and Logging Tool

Access to the temporary storage area shall be limited to the contractor radiation workers only.

The contractor Logging Engineer, only, shall perform the transfer of radioactive sources from transport shield to tool, and vice-versa.

A suitable handling tool that maximises the distance from the engineer to the unshielded source shall be used. This handling tool shall be fitted with a secondary security clip to ensure that the source, if accidentally displaced from the grip of the handling tool, will not fall free.

The transfer from shield to tool shall take place as close as possible to the wellhead to minimize the handling of the tool after loading the source and reduce the time to introduce it in the well.

The well, if open, shall be effectively covered with a plate during transfer of the source from shield to tool and vice-versa to prevent accidental loss of the source down hole.

2.1.7.6 Operations with Pulsed Neutron Tools (GST)

The minitron of the GST tool, once activated by the application of high voltage ("Neutrons on"), emits high energy (14 MeV) neutrons with an activity the equivalent of more than 100 standard Neutron logging sources (16 Ci-AmBe) and is, therefore, extremely dangerous to personnel.

The minitron, when deactivated, is a weak emitter of alpha particles (from the small quantity of Tritium gas present) that are normally absorbed entirely by the minitron housing itself. However, if the housing is ruptured, the tritium will be released and since Tritium is water-soluble and easily absorbed by plastics the risk of contamination is quite high.

Minitrons shall, therefore, only be activated at surface by a competent person under strictly controlled circumstances in the designated calibration facility of the contractor.





Minitrons shall never be activated on surface at the wellsite under any circumstances and shall only be powered in the well when the tool is at a depth greater than 25 m.

Tools containing Minitrons shall not be removed from the well for a period of 15 minutes following deactivation as the minitron will continue to emit neutrons for a "cooling down" period after removal of the high voltage activation.

If there is the slightest suspicion that the minitron may have ruptured, or the tool containing the minitron may have become flooded with well fluid, then that portion of the tool shall not be opened at the wellsite under any circumstances.

The tool shall be sealed in a strong plastic bag and returned to the contractor's maintenance facilities, where specific procedures and equipment are available to handle such equipment.

2.1.8 Naturally Occurring Radioactive Material (NORM)

2.1.8.1 General

Occasionally Naturally Occurring Radioactive Material (NORM) is encountered during Well Services operations in the form of low specific activity (LSA) scale, which is composed of non-radioactive sulphates containing a mixture of radium 226 and its derivatives.

LSA scale and associated contaminated materials may be deposited on the inside of wellheads and tubing/subsurface assemblies pulled from wells or on wireline equipment that has been downhole for lengthy periods.

Consideration must be given both to the people actually working on Well Services operations (well pulling and wireline) who may encounter such material and members of the public who may enter the area after the completion of operations.


The main risks from LSA scale and NORM contaminated materials are inhalation and ingestion and protective measures must be taken to ensure that neither of these can occur.

If NORM is suspected to be present in any well scheduled for well pulling or wireline operations monitoring equipment (Mini Instrument 44A monitor) shall be on site before operations commence.

The following Personal Protective Equipment shall also be available on site before operations commence and shall be worn by all personnel who are likely to come into contact with contaminated tubulars and/or wireline tools and equipment pulled from suspect wells:

white one-piece disposable suits;

rubber gloves;

rubber boots;

safety helmet;

eye protection;

respirator (oral/nasal mask 3M type 8835 or equivalent.

Smoking, eating or drinking shall not be allowed in the immediate area of operations.

Any cuts, abrasions, etc. shall be covered by a waterproof dressing.

All tubulars and downhole equipment and tools shall be monitored for the presence of NORM as they are retrieved from the well.

All joints of tubing with contaminated scale or solids inside shall be sealed with end caps and labelled with ‘NORM’ tape.

If scale or contaminated solids are present on the outside of tubulars and/or tools and equipment, these shall be wrapped in polythene that shall be sealed and labelled as above.




All contaminated tubulars, equipment and tools shall be despatched to Bahja for cleaning and disposal of the debris.

Any debris dislodged from the downhole equipment shall be carefully collected and wrapped in polythene together with any solids cleaned from rubber gloves and boots, etc. A sample of the solids shall be labelled and sent to the Production Chemistry Laboratory for analysis.

The rubber gloves and boots shall be carefully washed ensuring that any contaminated solids are collected. The disposable suits and collected contaminated solids shall be wrapped in polythene and sent to Bahja for disposal.

After completion of operations and rig down, the site shall be monitored to check for NORM contamination and any remaining debris collected.

All personnel shall be monitored for NORM contamination as they leave the site, particularly the soles of their boots, and any remaining contamination shall be washed off ensuring that solids are collected for disposal. After leaving the site all personnel must wash their hand as soon as possible s , especially before eating or smoking.





3 Hazards

The following hazards or threats have been identified as being prevalent during the process covered by this Specification. These are assessed and the controls to be applied are given in the Hazards Register, which forms Part 5 of Volume 1 of GU-458, Well Engineering Combined Operations HSE Case

REF HAZARD

H-01.02a Hydrocarbons in Formation / at Surface (drilling ops)

H-01.02b Hydrocarbons in Formation / at Surface (well services)

H-02.03 Diesel Fuel (fuel source)

H-04 Explosives

H-05.01 Bottled Gases Under Pressure

H-05.04a Air Under High Pressure (drilling ops)

H-05.04b Air Under High Pressure (well services)

H-05.07a Fluids Under High Pressure (drilling ops)

H-05.07b Fluids Under High Pressure (well services)

H-06.01a Personnel Working at Heights (drilling ops)

H-06.01b Personnel Working at Heights (well service)

H-06.01c Personnel Working at Heights (man riding winch)

H-06.02 Personnel at Height <2m – Slippery / Uneven Surfaces

H-06.03a Overhead Equipment (drilling ops)

H-06.03b Overhead Equipment (well services)

H-06.03c Overhead Equipment (crane, forklift, air winch ops)

H-06.06 Elevated equipment (tubular on pipe rack or catwalk)

H-07.01 Objects under tension (wireline cable)

H-08.01 On land transport – onsite vehicles

H-08.05a Equipment with moving / rotating parts (ex drill floor equipment)

H-08.05b Equipment with moving / rotating parts (drill floor equipment)

H-08.06 Use of Hazardous Hand Tools

H-08.09 Moving or Rotating Equipment (drill floor)

H-13.02 Liquid Nitrogen

H-15.02 Voltage >50 to 440V in Equipment

H-15.03 Voltage >440 Volts

H-17 Open Source Radiation

H-18 Closed Source

H-19.01 Insufficient Oxygen Atmosphere – Confined Space Entry

H-20.01 Hydrogen Sulphide

H-23.01 Hydrofluoric Acid

H-23.02 Hydrochloric Acid

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REF HAZARD

H-25.01 Manual Materials Handling






4 Roles and Responsibilities

Table ‎4-1, Roles and Responsibilities

Role Responsibility

The Asset Team The Asset Team will provide on site Petroleum Engineering and Operations support as necessary for all Well Services operations.

Well Services Site Supervisor The Site Supervisor is responsible for ensuring that Toxic Data Sheets for all treatment fluids to be used, including acids and additives (such as inhibitors, surfactants, friction reducers etc.), are available on the wellsite.

The Site Supervisor shall refer to these safety Data Sheets to determine what precautions or specific procedures are required in normal and emergency situations prior to the commencement of operations.

In the event of evacuation of the wellsite following discharge line failure, fire, or any other emergency, the Site Supervisor is responsible for assessing the situation, and if considered safe, directing designated personnel to close the well master valve and storage tank valves.

He will also arrange onsite storage and transport of toxic or contaminated waste to the Company approved waste sites.

All Site Supervisors, Company or contractor, shall be fully trained in First Aid and be knowledgeable in the treatment for exposure to toxic and flammable liquids and vapours and the treatment of burns.

They shall also be specifically trained in the hygiene standards and environmental controls necessary when handling hazardous pollutants such as aromatics.

Contractor Logging Engineer The Contractor Logging Engineer has sole responsibility for the handling and removal of sealed radioactive sources from their transport shield whilst on the wellsite (transfer of sources from shield to tool and vice-versa).

All personnel on the wellsite shall defer to the judgement of the Contractor Logging Engineer, who is a designated "Competent Person" in matters related to operations with sources of Ionising Radiation.

The Contractor Logging Engineer is responsible for performing the work involving radioactive sources in accordance with PDO and his company's internal procedures, in a manner that protects all personnel, installations and the environment from all damage by irradiation or contamination.

Contractor Well Services Engineer

The Contractor Wireline Engineer is responsible for arming and disarming all explosive devices with primary high explosive detonators.

He is also responsible for monitoring the voltage between major site equipment, i.e. WPH, and wellhead (casing) prior to initiating any operation with electrically detonated explosive devices to verify that stray currents have been eliminated.




Role Responsibility

Contractor Stimulation Supervisor

It is the responsibility of the Contractor Stimulation Supervisor to ensure that all his personnel are familiar with the Data Sheets.

He shall be fully trained in First Aid and be knowledgeable in the treatment for exposure to toxic and flammable liquids and vapours and the treatment of burns and be specifically trained in the hygiene standards and environmental controls necessary when handling hazardous pollutants such as aromatics.

He will ensure that all members of the stimulation crew are trained in basic fire fighting, with specific knowledge of the use of dry powder extinguishers in combating flammable liquid fires.

Company WSOE or Contractor Rig Manager

The Company WSOE or in his absence the Contractor Rig Manager is responsible for ensuring that all operations involving the use of radioactive sources are carried out in a safe manner, in accordance with procedures, requesting assistance and advice in the case of an emergency.





5 Appendices

5.1 Appendix 1, Forms and Reports

The following forms are used in relation to this Specification:

Step-Out Request Form

Well Location Custodianship Transfer Form

The PDO Site Supervisor will ensure that a Pre-Stimulation Audit Checklist is completed jointly with the Contractor Stimulation Supervisor, and any shortfalls rectified, before the stimulation operations commence.

The Well Location Custodianship Transfer Form is described in PR-1098, Well Activity Co-ordination and Control Procedure

5.2 Appendix 2, Glossary of Terms, Abbreviations and Definitions

Table ‎5-1, Glossary of Terms, Abbreviations and Definitions

Term/Abbreviation Definition

May Indicates one possible course of action

Should Indicates a preferred course of action

Shall Indicates a mandatory course of action

µSv/hr micro sievert per hour (dosage of ionizing radiation)

BLEVE Boiling Liquid Expanding Vapor Explosion

BOPs Blow Out Preventers

CDFP Corporate Discipline Focal Point (as designated by Section Head)

CITHP Closed In Tubing Head Pressure

CST Core Sampling Tool

CTU Coiled Tubing Unit

Livelink Electronic Document Data base System

EED Electrical Explosive Detonator

HCl Hydrochloric acid

HF Hydrofluoric Acid

LSA Low Specific Activity (Scale)

NORM Naturally Occurring Radioactive Material

RVP Reid Vapour Pressure

SCBA Self-Contained Breathing Apparatus

SHOC Safe Handling of Chemicals (Cards)

TCP Tubing Conveyed Perforator

VP Vapour Pressure

WPH Well Pulling Hoist

WSOE Well Site Operations Engineer


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5.3 Appendix 3, Related Business Control Documents and References

Table ‎5-2, Related Business Control Documents and References

Document Co.

CMF Business Control Portal PDO

Well Engineering Documentation Page PDO

PR-1444, Well Engineering and Logistics Management Framework PDO

SP-2037, Well Engineering Specification for the Use of Equipment in Hazardous Areas

PDO

SP-1194, HSE Specification - Chemical Management PDO

SP-1009, HSE Specification - Waste Management. PDO

GU-458 - Well Engineering Combined Operations HSE Case PDO

SP-1234, HSE Specification - Personal Protective Equipment PDO

SP-1237, HSE Specification - Ionising Radiation PDO

PR-1418, Incident Notification, Reporting and Follow-up Procedure Part 1

PR-1084, Leak / Spill Management, Site Clean-Up and Restoration.

SP-1216, WE Specification for Explosives

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