Offshore Ocean Engineering Copyright KohKho King …koh/smk4122/Introduction to Offshore Engineering.… · Fixed platform – steel jacket, ... first spar platform, Neptune,

SMK4122 Offshore & Ocean Engineering | Copyright © 2012 Koh Kho King

WELCOME

SMK4122Offshore & Ocean Engineering

Dr. Koh Kho King

Room: C25‐315 | h/p: [email protected] | http://www.fkm.utm.my/~koh


Aims

• To introduce oil and gas industry activities in general

• To encompasses various components in the oil and gas activities

• Introduction to survey, exploration, platform construction, installation, production, and maintenance in oil and gas industry

• Introduction to various types of offshore platforms and their uniqueness and functionality


Course Learning Outcome

• Describe the overall scenario of global and local oil and gas industry

• Identify and describe the main components & activities in the offshore oil and gas industry.

• Describe the main processes in the design and construction engineering of Offshore structure

• Explain the various rules and regulations in the Offshore industry


Course Contents

1. Introduction• Background on Oil and Gas Industry • Oil and Gas operation activities. Types of Offshore Platforms.• Oil Drilling and Oilfield Services. High technology exploration

and production methods


• Offshore platform ‐> use for underseabed exploration and processing

• First Offshore platform ‐ installed in 1947 off the coast of Louisiana in 6m depth of water

• Today over 7,000 Offshore platforms around the world with some in water depths over 2,000m

Background


Platform size depends on facilities to be installed on top side eg. Oil rig, living quarters, Helipad etc.Classification of water depths:

– < 350m - Shallow water

– < 1500m - Deep water

– > 1500m - Ultra deep water

– US Mineral Management Service (MMS) classifies water depths greater than 1,300 ft as deepwater, and greater than 5,000 ft as ultra-deepwater.

Background


Oil & Gas Industry

The Oil & Gas Industry comprises two parts:

Upstream – the exploration and production sector of the industry

Downstream – the sector which deals with refining and processing of crude oil and gas products; their distribution and marketing


Oil & Gas Industry

Exploration : Analysing and Interpreting seismic data to determine the potential of hydrocarbon reserves; drilling of test wells.

Conceptual development: Screening studies to determine the most efficient and cost effective method to produce potential hydrocarbon sources i.e selection of facilities, transport of hydrocarbon from field to customer (pipeline, floating storage and offloading (FSO) Vessels, corrosion mitigation strategies and safety aspects of the operations.

Development: project management of construction, detailed engineering, optimum wells location, transport of facilities to location and commissioning of facilities

Production : maintenance strategies, planing budges, Analysis of supply and demand, and retrofit work to maintain or meet new production targets.

Among the upstream activities would be:


Malaysian O & G Industry(1)

• Petroleum exploration in Malaysia started at the beginning of the 20thcentury in Sarawak, where oil was first discovered in 1909 and first produced in 1910.

• Prior to 1975, petroleum concessions were granted by state governments, where oil companies have exclusive rights to explore and produce resources. The companies then paid royalties and taxes to the government.

• This state of affairs ceased on April 1, 1975 as a result of the Petroleum Development Act, whereby PETRONAS became the custodian of petroleum resources with rights to explore and produce resources. The national oil company retains ownership and management control in exploration, development and production of oil resources. Expenditure and profits are managed under instruments called Production Sharing Contracts (PSCs).



• Malaysia has the 25th largest oil reserves and the 14th largest gas reserves in the world.

• The total reserves is of the order of 18.82 billion barrels oil equivalent (boe) with a crude production rate of 600 thousand barrels per day.

• The average natural gas production stands to approx. 5.7 billion standard cubic feet per day.



• Malaysia has the 494,183 km2 of acreage available for O&G exploration, with 337,167km2 in the offshore continental shelf area and 63,968 km2 in deepwater.

• The acreage is split into 54 blocks, out of which 28 (a total of 205,500km2) are currently operated by Petronas Carigali Sdn. Bhd plus seven other multinational oil companies.



Historical Natural Gas Production



Historical Crude Oil Production


Oil & Gas Activities

NO OPERATION TYPE OF STRUCTURE

1 Survey Survey ship, oceanagraphic platform/buoy

2 Wild cat or exploratory drilling Jackup, barge, drillship, semisubmersible

3 Pipe-laying Pipe-laying barge, ship, semisubmersible

4 Supply and Anchor Handling Supply vessel, platform supply vessel

5 Towing Ocean-going Tug

6 Diving Diving support vessel

7 Production Fixed platform – steel jacket, concrete gravity type, TLP, guyed tower

8 Heavy Lift Semisubmersible Crane Vessel, Crane Barge, Crane Ship

9 Offshore Terminal Single Buoy Mooring (SBM), SPAR Buoy

10 Underwater Inspection Submersible – ROV, manned


Cost Vs Water Depth

Fixed TLP

Floating

Initial Cost+

Installation

Water Depth


Seismic Survey(1)


Seismic Survey(2)

• Petroleum – Petra (rock) + Oleum (Oil)

• Source Rock, Reservoir Rock, Cap Rock

• Wild‐Cat, Appraisal and Development drilling


Oil & Gas Activities

Upstream

Downstream


Types of Offshore Structure

Jack up TLP

Classification of Offshore Structures

Floating

Compliant

Gravity

FixedSemisubmersible

Crane bargeDrillship

Articulated columns

Guyed Tower

Jacket


Types of Offshore Structure


• Fixed structures that extend to the Seabed.

• Steel Jacket• Concrete gravity

Structure• Compliant Tower

Offshore Platform


• Structures that float near the water surface‐ Recent development

• Tension Leg platforms• Semi Submersible• Spar• Ship shaped vessel

(FPSO)

Offshore Platform


JACKET PLATFORMSpace framed structure with tubular members supported on piled foundations. Used for moderate water depths up to 400m.Jackets provides protective layer around the pipes.Typical offshore structure will have a deck structure containing a Main Deck, a Cellar Deck, and a Helideck. The deck structure is supported by deck legs connected to the top of the piles. The piles extend from above the Mean Low Water through the seabed and into the soil.

Fixed Type Platforms


JACKETED PLATFORM (Cont.)Underwater, the piles are contained inside the legs of a “jacket” structure which serves as bracing for the piles against lateral loads. The jacket also serves as a template for the initial driving of the piles. (The piles are driven through the inside of the legs of the jacket structure).Natural period (usually 2.5 second) is kept below wave period (14 to 20 seconds) to avoid amplification of wave loads.95% of offshore platforms around the world are Jacket supported.



Jack Up


Jacket


COMPLIANT TOWERNarrow, flexible framed structures supported by piled foundations. Has no oil storage capacity. Production is through tensioned rigid risers and export by flexible or catenary steel pipe. Undergo large lateral deflections (up to 10 ft) under wave loading. Used for moderate water depths up to 600m.Natural period (usually 30 second) is kept above wave period (14 to 20 seconds) to avoid amplification of wave loads.



CONCRETE GRAVITY STRUCTURESFixed-bottom structures made from concrete Heavy and remain in place on the seabed without the need for pilesUsed for moderate water depths up to 300 M.Part construction is made in a dry dock adjacent to the sea. The structure is built from bottom up, like onshore structure.At a certain point , dock is flooded and the partially built structure floats. It is towed to deeper sheltered water where remaining construction is completed.After towing to field, base is filled with water to sink it on the seabed. Advantage - Less maintenance



Tension Leg Platform (TLP)Tension Leg Platforms (TLPs) are floating facilities that are tied down to the seabed by vertical steel tubes called tethers.This characteristic makes the structure very rigid in the vertical direction and very flexible in the horizontal plane. The vertical rigidity helps to tie in wells for production, while, the horizontal compliance makes the platform insensitive to the primary effect of waves.

Have large columns and Pontoons and a fairly deep draught.

Floater Type Platforms


Tension Leg Platform (TLP)TLP has excess buoyancy which keeps tethers in tension. Topside facilities , no. of risers etc. have to fixed at pre-design stage.

Used for deep water up to 1200 MIt has no integral storage.It is sensitive to topside load/draught variations as tether tensions are affected.



SEMISUB PLATFORMDue to small water plane area , they are weight sensitive. Flood warning systems are required to be in-place.Topside facilities , no. of risers etc. have to fixed at pre-design stage. Used for Ultra deep water.Semi-submersibles are held in place by anchors connected to a catenary mooring system.



SEMISUB PLATFORMColumn pontoon junctions and bracing attract large loads.Due to possibility of fatigue cracking of braces , periodic inspection/ maintenance is prerequisite

Semi-submersible


Semi-submersible


SPAR:Concept of a large diameter single vertical cylinder supporting deck.These are a very new and emerging concept: the first spar platform, Neptune, was installed off the USA coast in 1997.Spar platforms have taut catenary moorings and deep draught, hence heave natural period is about 30 seconds.Used for Ultra deep water depth of 2300m.The center of buoyancy is considerably above center of gravity, making Spar quite stable.Due to space restrictions in the core, number of risers has to be predetermined.

SPAR


SPAR


SHIP SHAPED VESSEL (FPSO)Ship-shape platforms are called Floating Production, Storage and Offloading (FPSO) facilities. FPSOs have integral oil storage capability inside their hull. This avoids a long and expensive pipeline to shore.Can explore in remote and deep water and also in marginal wells, where building fixed platform and piping is technically and economically not feasibleFPSOs are held in position over the reservoir at a Single Point Mooring (SPM). The vessel is able to weathervane around the mooring point so that it always faces into the prevailing weather.

FPSO


OSV


TOPSIDE:Facilities are tailored to achieve weight and space savingIncorporates process and utility equipment

Drilling RigInjection CompressorsGas CompressorsGas Turbine GeneratorsPipingHVACInstrumentation

Accommodation for operating personnel.Crane for equipment handlingHelipad

Parts of Platform


MOORINGS & ANCHORS:Used to tie platform in place Material

Steel chainSteel wire rope

Catenary shape due to heavy weight. Length of rope is more

Synthetic fiber ropeTaut shape due to substantial less weight than steel ropes.Less rope length requiredCorrosion free

Parts of Platform (cont.)


RISER:Pipes used for production, drilling, and export of Oil and Gas from Seabed.Riser system is a key component for offshore drilling or floating production projects.The cost and technical challenges of the riser system increase significantly with water depth.Design of riser system depends on filed layout, vessel interfaces, fluid properties and environmental condition.

Parts of Platform (cont.)


BARGE LOADOUT:– Various methods are deployed

based on availability of resources and size of structure

Barge CraneFlat over - Top side is installed on jackets. Ballasting of bargeSmaller jackets can be installed by lifting them off barge using a floating vessel with cranes.

– Large 400’ x 100’ deck barges capable of carrying up to 12,000 tons are available

Platform Installation


Oil Drilling(1)

• Drilling rigs: Exploration of oil and gas Stay in a place for a few months (Mobile or movable)

‐ Jack‐up drilling rig‐ MODU (Mobile Offshore Drilling Unit)

• Production platforms: Production of oil and gasStay in a place for at least a few years (usually 20 ‐30 years)

‐ Ground‐base structure ( <500~800 m)‐ Floating Structures (> 800 m)


Oil Drilling(2)Offshore Drilling Equipment • The drill string is lowered through a conduit (riser).

Consists of a drill bit, drill collar and drill pipe. Drill pipe sections are added at the surface as the well deepens. The drill passes through a system of safety valves called a Blowout Preventer (BOP) stack which contains the pressures in the well to prevent a blowout (escape of pressure into the annular casing between the casing and the drill pipe or into the hole).

• Drilling fluid (mud) is pumped into the drill pipe from the surface and flows through small holes in the drill bit. The mud collects rock cuttings and flows up the annulus between the drill pipe and the casing where the rock is strained out and the mud is recirculated. The weight of the mud exerts a pressure on the rock and keeps the well under control.


Accident

P - 36 accident in 2001

Model of Ocean Ranger, which capsized in 1982, during survival testing


Accident

Severe damage caused on a jacket platform in the Gulf of Mexico by Hurricane Lilli

Piper Alpha fire and explosion in 1988


Accident

Gulf of Mexico Oil Spills


Accident



Accident



Offshore Practice Codes

Offshore Standards (OS)Provides technical requirements and acceptance criteria for general application by the offshore industry eg. DNV-OS-C101

Recommended Practices(RP)Provides proven technology and sound engineering practice as well as guidance for the higher level publications eg. API-RP-WSD

BS 6235: Code of practice for fixed offshore structures

British Standards Institution 1982

Mainly for the British offshore sector


References

W.J. Graff: Introduction to offshore structures.

Gulf Publishing Company, Houston 1981.

Good general introduction to offshore structures.

B.C. Gerwick: Construction of offshore structures.

John Wiley & Sons, New York 1986.

Up to date presentation of offshore design and construction.

Patel M H: Dynamics of offshore structures

Butterworth & Co., London.

• Google Images

• Wikipedia

Documents

Offshore Ocean Engineering Copyright KohKho King …koh/smk4122/Introduction to Offshore Engineering.… · Fixed platform – steel jacket, ... first spar platform, Neptune,