12. Horizontal Well

Completion

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Topics Covered

Planning the horizontal well

completion

Horizontal well completion

techniques

Equipping the horizontal well

Working in the horizontal well

environment

Logging and perforation

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Horizontal Well Completion

Horizontal well (HW) drilling is potentially the most important completion technique since hydraulic

fracturing

HW is normally drilled vertically to a particular depth and horizontally to additional hundreds or

thousands feet

HW is classified based on its turning radius

R = 57.3/BUR (buildup rate, o/ft)

Three types: short, medium, and long-radius

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Completion of Horizontal Wells

HW completion depends on formation characteristics, reservoir type, and drilling

technique

Formation characteristics: homogeneous or heterogeneous

Reservoir type: gas or under-saturated or saturated or heavy oil

Drilling technique: short or medium or long-radius method

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Completion Types

Two types: open hole and cased-cemented completion

Open hole:can be true or pseudo open hole

true OH in competent formation with no water or gas

pseudo OH with slotted liners and/or ECP for isolation

Cased-cemented hole

premium completion (very expensive)

need to perforate; last option

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Horizontal Open-Hole Completion

This is a true open hole completion and it is used in consolidated

and competent formation with medium to high permeability

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Horizontal Perforated Liner Completion

(pseudo open-hole)

The pre-perforated liner/casing is used where little or no stimulation is required, and

the segmented uncemented liner/casing is used for open-hole evaluation of the

wellbore and subsequent selective stimulation, if necessary.

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Horizontal Perforated Liner Completion

(pseudo open-hole)

The pre-perforated liner/casing is used where little or no stimulation is required, and

the segmented uncemented liner/casing is used for open-hole evaluation of the

wellbore and subsequent selective stimulation, if necessary.

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Running of a horizontal pre-pack liner/screen

The slotted or pre-perforated liner/casing is used where little or no stimulation is

required, and the segmented uncemented liner/casing is used for open-hole

evaluation of the wellbore and subsequent selective stimulation, if necessary.

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Horizontal Well Selective

Completion with ECP

External casing

packers

The pre-perforated liner/casing is used here with some external casing packers (ECP).

The ECPs are used for isolation of the hole segments that showed little or no

production.

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Horizontal well cased and

cemented liner completion

1. The cased and cemented completion is the premium completion approach. This

means that the well must be perforated and stimulated.

2. Costs associated with these operations are so significant that there must be

problems associated with the wellbore/formation combination that cannot be

addressed in any other way

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Equipping the Horizontal Wells Most tools are set with rotation movement, or hydraulic pressure,

which must be applied around the bend to the horizontal segment.

Major tools are external casing packers (ECP), bridge plugs, packers,

and artificial lift devices (pumping equipment)

The tool size and operation are the most important parameters for the tools

Length L, and diameter of the a rigid tool that can be run around the bend is a f(R)

L = 1/6[R2 - (R -d)2]0.5; d = IDcasing - ODtool

L = tool length, ft; R and d are in inches

All tools are set by mechanical, or hydraulic or passive action. The movement required to set or unset a tool should be minimized.

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Effect of radius of curvature on the length of tool that can be run in a horizontal well

1. The length and diameter of a

rigid tool that can be transported

around a curve is dependent on

the curve radius and the tool

clearance.

2. The maximum length of any

specific diameter of tool to be

transported around a curve can

be calculated using the equation

L = 1/6[R2 - (R -d)2]0.5;

d = IDcasing ODtool; L = tool length, ft;

R and d are in inches

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Multiphase flow patterns in a

horizontal well

The dips and rises in the

well profile act as down-

hole separators for the

various phases of the

produced fluids, leading to

slug flow

These slugs may be big

enough to load up and kill

the well. Thus, tubing

should be landed at the

low point in the lateral so

as to minimize slugging.

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Figure 6.11 - Horizontal well perforation configuration in consolidated (360 phasing) and unconsolidated (120 - & 180 -

phasing) formations

Perforation of Horizontal Wells

Gun orientation - full phase (360o) in consolidated formations and 180o or

120o-phase in unconsolidated formations

Perforation density - use a lower shot density (2-shots/ft). This is

because so much zone is exposed in horizontal wells plus perforating is

expensive

Use bullet guns in low compressive formation and jet guns in high

compressive formation

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Artificial Lift Equipment in HW

These are gas lift, hydraulic jet, and electric submersible pumps

Gas lift - a viable option in short and medium-radius, may be uneconomical in long-radius

Hydraulic jet pumps - affected slightly by hole inclination but inefficient in low pressure wells

Electric submersible pumps - not good in high angle wells and must be centralized. Also, very sensitive to

high GOR. Have ability to lift large amount of fluids

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Working in Horizontal Well

Hole cleaning - use high viscous pill or magnet

Tubing stress at the bend - use flexible material

Perforation

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Coiled Tubing Conveyed Logging Tools

CT has three main parts: measuring tools and protection equipment, an

electric connector between tool and

drill pipe, and slide entry capability.

It is important to prevent damage to cable by not lowering the slide entry

sub beyond certain inclination or

protect it by clamping along drill

pipe.

1. Advantages: easy and rapid to use (significant reduction in rig time), accurate depth

control, and the ability to make multiple runs.

2. Disadvantage: CT will buckle when the frictional forces associated with the guns in the

horizontal hole exceed the CT critical buckling load. The advantages of CT are the

speed of running the guns, the ability to log perforating guns on depth,

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Nitrogen kickoff of a well using

coiled tubing

1. This figure shows one of the

major applications of CT

(nitrogen kickoff)

2. 25% of the CT business

accounts for nitrogen kickoffs.

3. It is possible to pump N2 too

fast Lighten column while RIH,

then pump N2 at bottom of well

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HW Cementing Problems & Solutions

Three main problems: free-water on the upper side

of well, deposition of solids, and inadequate

fluid/cement displacement

Associated problems include mud and gas channeling

Solutions include the following:

Good cement and fluid design;(YP30 lbf/100 ft2)

Use mechanical devices - centralizers & scratchers

Use mechanical actions - rotate/reciprocate

Displace cement and fluid in turbulent flow

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A typical flow meter for production logging on coiled tubing

1. This figure shows another application of CT (production

logging). The production profile of a horizontal well is

often required for effective production management. To

optimize well production, pressures and entry points of

water, oil, and gas are the necessary data. One of the

biggest problem is measuring and interpreting

multiphase flow of the fluids especially in horizontal

wells.

2. Two techniques have been developed to improve the

quality of data measurement of two-phase flow in

horizontal wells and to determine the location of fluid

flux. These techniques, using CT, involve (a) a small

variable-diameter metal petal-basket and a fluid

analyzer tool, and (b) a temperature survey tool to

measure temperature anomalies during production or

injection of fluids.