01-Reservoir 02-Well Completion Methods

Well Completion Techniques

Copyright 2008, NExT, All rights reserved

Objectives At the end of this lecture, you should be able to:

Describe typical completion procedures

List and describe basic well completion techniques

List the advantages and disadvantages of the well completion techniques


Well Completions

After drilling, the well is “completed” for production of oil or gas May use the drilling rig for the initial well completion or utilize workover/completion rig Decision is based on location and economics


Well Completion Operations Consists of a series of operations whose aim is to provide the means of communication between the reservoir and the surface: Perforating Sand control installation Production packer setting Running the tubing string (with its components) Safety valve installation (SSSV, SCSSV) Xmas tree installation


Well Completion Techniques Open hole Liner (cemented, slotted or perforated) Cased hole Tubingless or Slimhole


Open Hole (Barefoot) Completion

Casing

New reservoir


Open Hole Completions Advantages Eliminate Casing and Perforating costs Maximum wellbore diameter opposite production interval Easy to deepen well if required Easily converted to screen or perforated liner completion Disadvantages Excessive Water or gas production difficult to control Not easy to stimulate producing interval Open hole section may require frequent clean–out Can only be applied in well consolidated formation Copyright 2008, NExT, All rights reserved

Liner Completions Slotted or perforated


Permanent

Screen/Slotted Liner Completions Advantages Relatively cheap because of casing cost savings Eliminate perforating costs Screen can be sized for sand control Improves bore–hole stability Disadvantages Excessive water or gas production difficult to control Mud cake not removed – can result in damage Not easy to stimulate producing interval – n o selectivity Reduced diameter across producing interval Copyright 2008, NExT, All rights reserved

Perforated Liner Completions Advantages

Excessive water and gas easily controlled Selective stimulation possible Relatively cheaper than Perforated Casing configuration Adaptable to sand control techniques Adaptable to multiple completions Production Logging easy to run

Disadvantages Well bore diameter restricted Perforating cost can be significant Greater danger of productivity impairment from completion skins Liner cementation not as easily or as good as primary cementation


Cased Hole

Oil or gas reservoir


Perforated Casing Completions Advantages Excessive water and gas easily controlled Selective stimulation possible Well can be easily deepened Adaptable to sand control techniques Adaptable to multiple completions Disadvantages Perforating cost can be significant Reduction of wellbore diameter Greater danger of productivity impairment from completion skins


Tubingless or Slimhole

Smaller diameter tubing string

Two to three strings can be run for multiple completions

Oil or gas reservoir


Completions Completion Type Cased Hole

Liner

-

Advantages Pressure control Isolation of zones Control of stimulation Wellbore Stability Less expensive than casing entire hole Pressure and stimulation control (when cemented) Wellbore stability Maximum flow area Minimize damage

Open Hole

-

Slimhole

- Lower Cost


Disadvantages - More expensive - Limited communication to reservoir - Possible cement damage - Cementing more difficult - No control of flow if not cemented - Slots plugged w/formation - Limited control of stimulation - No control of flow - Limited or no control of stimulation - Hole collapse in weak formations - Limited Workover capability due to small hole - Limited stimulation rate - No zone isolation

Typical Casing Schemes Cemented Liner

Conventional Cemented

20”

18 5/8

13 3/8

13 3/8

Cemented Monobore

13 3/8

9 5/8” 9 5/8”

9 5/8”

4 1/2” tubing 7” Copyright 2008, NExT, All rights reserved

3 1/2” tubing 7”

5½”

7”

5½”

Well Completions (Vertical Wells)

Single Zone Multiple Zones


Single Zone Completion * Single zone completion - One reservoir is producing. Open-ended


Packer

Multiple Zone Completion * Multiple zone completion - More than one reservoir is producing. Open - ended (Commingled)


Dual packer

Deviated and Horizontal Wells Special application of basic completion methods Early approach was to utilize openhole completions in horizontal wells

Problems with sand control

Problems with controlling fluids

Issues with standard completion equipment

Wireline tools, etc.


Deviated Wells Deviations up to approximately 60-65o Standard equipment generally suitable Tool length and diameter of major concern Radius of curvature of drilled wellbore Affects ability to run casing Limits tool length Affects artificial lift installations


Horizontal Wells Required new/modified completion equipment or techniques

Zonal isolation

Placement of equipment in horizontal

Stimulation techniques

Perforating

Production logging

Intervention Issues


Horizontal Completions Openhole Completion True openhole Slotted or preperforated liner/casing Segmented uncemented liner/casing Cased and Cemented Completion Premium completion Liner/casing run to end of horizontal and cemented in place


Slotted Liner in Open Horizontal Hole PACKER

• Used worldwide • Prevents hole collapse • Eases re-entry • Total lack of zone isolation options

LINER HANGER

Slotted Liner


• Do not use where water breakthrough is anticipated • Do not use where stimulation is required

Cemented Conventional PACKER

North Sea Far East

Europe Alaska

• Conventional completion turned horizontal • All zone isolation & flow control options LINER HANGER

CEMENT PERFORATIONS


• High expense • Loss of productivity . Formation damage from cement . Perforation damage

West Africa - Horizontal Well

4 1/2” tubing

Packer SC-1LR

Seal bore receptacle Bull plug

0.012” pre-packed slim pak screens Copyright 2008, NExT, All rights reserved

0.040” slotted liner

West Africa - ECP with Slotted Liner 5 1/2” TR-SSSV 5 1/2” Tubing

Side Pocket Mandrel (Gaslift) 1

4 /2” Tubing

External Casing Packer

Permanent gauges

SPM (Circulation) ELTSR 9 5/8” Packer (ca 60°) 9 5/8” Shoe (90°) Copyright 2008, NExT, All rights reserved

8 1/2” Lateral drainage hole: 2000 - 3000 Ft.

IT 4447485 Copyright 2008, NExT, All rights reserved

Considerations Type of formation

Homogeneous

Heterogeneous

Naturally Fractured

Type of well

Oil or gas

Near oil/gas contact or oil/water contact


Homogeneous Formation Easy to accommodate completion design Generally requires little isolation of zonal segments Well adapted to openhole completion if reservoir is competent


Heterogeneous Formation Reservoir quality and pressure can vary of horizontal length May require “segments” be isolated to accommodate selective stimulation Depending on permeability, some sections may require little or significant stimulation Cemented and perforated or segmented uncemented liner completion appropriate


Naturally Fractured Reservoir Must pick proper wellbore orientation Desire to intersect the maximum number of fractures by drilling perpendicular to the fracture orientation Must leave fractures in an undamaged state Best suited for openhole or preperforated liner completion


Naturally Fractured Reservoir If fracture density is low, then well may not be economical without massive stimulation Cased and cemented completion will allow hydraulic fracture treatment to attempt to create fractures perpendicular to the wellbore


Oil and Gas Wells Stimulation requirements dictate best well completion approach

Can you obtain suitable stimulation with the casing completion configuration?

Small acid treatments may be accomplished in an openhole or uncemented liner completion

Large hydraulic fracture treatment will generally require cased and cemented completion


Gas/Oil or Oil/Water Contacts Need the ability to perform remedial actions in the horizontal section May require the ability to provide zonal isolation Selective isolation ability is a major benefit in the completion design

External casing packers (ECP)

New “sliding sleeve” or ported liners


- South America

TVD

CASING 7” - N80

Leg “A” Azimuth 48°

Leg “B” Azimuth 197° KOP = 1040 m

MD = 1421 m Dev = 89.3° TVD = 1106

KOP = 1054 m

MD = 1435 m Dev = 90.6° TVD = 1102

Casing 3 1/2” Open Hole 6 1/8”

240 m Copyright 2008, NExT, All rights reserved

Open Hole 6 1/8”

311m

Well Planning- Drivers An “Effective” Well is that Well which contributes maximum monetary value over its life cycle. Key Drivers

Optimize well costs

Optimize well productivity

Optimize life-cycle operating expense


Summary You should now be able to:

List typical and describe completion techniques for vertical, deviated and horizontal wells

List advantages and disadvantages for the completion techniques

Describe typical completion procedures


01-Reservoir 02-Well Completion Methods

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