01-Reservoir 02-Well Completion Methods

Copyright 2008, NExT, All rights reserved

Well CompletionTechniques


Objectives

At the end of this lecture, you should be able to:Describe typical completion proceduresList and describe basic well completion techniquesList 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 installationProduction packer settingRunning 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

New reservoir

Casing


Open Hole Completions

AdvantagesEliminate Casing and Perforating costsMaximum wellbore diameter opposite production intervalEasy to deepen well if requiredEasily converted to screen or perforated liner completion

DisadvantagesExcessive Water or gas production difficult to controlNot easy to stimulate producing intervalOpen hole section may require frequent clean–outCan only be applied in well consolidated formation


Liner Completions

Slotted orperforated Permanent


Screen/Slotted Liner Completions

AdvantagesRelatively cheap because of casing cost savingsEliminate perforating costsScreen can be sized for sand controlImproves bore–hole stability

DisadvantagesExcessive water or gas production difficult to controlMud cake not removed – can result in damage Not easy to stimulate producing interval – n o selectivityReduced diameter across producing interval


Perforated Liner CompletionsAdvantages

Excessive water and gas easily controlledSelective stimulation possibleRelatively cheaper than Perforated Casing configurationAdaptable to sand control techniquesAdaptable to multiple completionsProduction Logging easy to run

DisadvantagesWell bore diameter restrictedPerforating cost can be significantGreater danger of productivity impairment from completion skins Liner cementation not as easily or as good as primary cementation


Cased Hole

Oil or gasreservoir


Perforated Casing Completions

AdvantagesExcessive water and gas easily controlledSelective stimulation possibleWell can be easily deepenedAdaptable to sand control techniquesAdaptable to multiple completions

DisadvantagesPerforating cost can be significantReduction of wellbore diameterGreater danger of productivity impairment from completion skins


Tubingless or Slimhole

Oil or gasreservoir

Two to three strings can berun for multiple completions

Smaller diametertubing string


Completion Type Advantages DisadvantagesCased Hole - Pressure control

- Isolation of zones- Control of stimulation- Wellbore Stability

- More expensive- Limited communication

to reservoir- Possible cement damage

Liner - Less expensive thancasing entire hole

- Pressure andstimulation control(when cemented)

- Wellbore stability

- Cementing more difficult- No control of flow if not

cemented- Slots plugged w/formation- Limited control of

stimulationOpen Hole - Maximum flow area

- Minimize damage- No control of flow- Limited or no control of

stimulation- Hole collapse in weak

formationsSlimhole - Lower Cost - Limited Workover

capability due to smallhole

- Limited stimulation rate- No zone isolation

Completions


7 7 ””

9 5/89 5/8””

13 3/813 3/8

2020””Conventional CementedConventional Cemented

5 5 ½½ ””

7 7 ””

9 5/89 5/8””

13 3/813 3/8

18 5/818 5/8Cemented LinerCemented Liner Cemented Cemented MonoboreMonobore

5 5 ½½ ””

7 7 ””

9 5/89 5/8””

13 3/813 3/8

4 1/24 1/2””tubingtubing

3 1/23 1/2””tubingtubing

Typical Casing Schemes


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 methodsEarly approach was to utilize openhole completions in horizontal wells

Problems with sand controlProblems with controlling fluids

Issues with standard completion equipmentWireline tools, etc.


Deviated Wells

Deviations up to approximately 60-65o

Standard equipment generally suitableTool length and diameter of major concern

Radius of curvature of drilled wellboreAffects ability to run casingLimits tool lengthAffects artificial lift installations


Horizontal Wells

Required new/modified completion equipment or techniques

Zonal isolationPlacement of equipment in horizontalStimulation techniquesPerforatingProduction loggingIntervention Issues


Horizontal Completions

Openhole CompletionTrue openholeSlotted or preperforated liner/casingSegmented uncemented liner/casing

Cased and Cemented CompletionPremium completionLiner/casing run to end of horizontal and cemented in place


Slotted Liner in Open Horizontal Hole

PACKER

LINER HANGER

Slotted Liner

• Used worldwide

• Prevents hole collapse

• Eases re-entry

• Total lack of zone isolation options

• Do not use where water breakthrough is anticipated

• Do not use where stimulation is required


Cemented ConventionalPACKER

LINER HANGER

CEMENT

North Sea EuropeFar East Alaska

• Conventional completion turned horizontal

• All zone isolation & flow control options

• High expense

• Loss of productivity. Formation damage from cement. Perforation damagePERFORATIONS


4 1/2” tubing

Packer SC-1LRSeal borereceptacle

Bull plug

0.040” slotted liner0.012” pre-packedslim pak screens

West Africa - Horizontal Well


West Africa - ECP with Slotted Liner

5 1/2” TR-SSSV

5 1/2” Tubing

Side Pocket Mandrel(Gaslift) 4 1/2” Tubing

SPM (Circulation)

Permanent gauges

ELTSR

9 5/8” Packer (ca 60°)

9 5/8” Shoe (90°)8 1/2” Lateral drainage hole: 2000 - 3000 Ft.

External Casing Packer


IT 4447485


Considerations

Type of formationHomogeneousHeterogeneousNaturally Fractured

Type of wellOil or gasNear oil/gas contact or oil/water contact


Homogeneous Formation

Easy to accommodate completion designGenerally requires little isolation of zonal segmentsWell adapted to openhole completion if reservoir is competent


Heterogeneous Formation

Reservoir quality and pressure can vary of horizontal lengthMay require “segments” be isolated to accommodate selective stimulationDepending on permeability, some sections may require little or significant stimulationCemented and perforated or segmented uncemented liner completion appropriate


Naturally Fractured Reservoir

Must pick proper wellbore orientationDesire to intersect the maximum number of fractures by drilling perpendicular to the fracture orientationMust leave fractures in an undamaged stateBest suited for openhole or preperforated liner completion


Naturally Fractured Reservoir

If fracture density is low, then well may not be economical without massive stimulationCased 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 approachCan you obtain suitable stimulation with the casing completion configuration?Small acid treatments may be accomplished in an openholeor uncemented liner completionLarge 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 sectionMay require the ability to provide zonal isolationSelective isolation ability is a major benefit in the completiondesign

External casing packers (ECP)New “sliding sleeve” or ported liners


TVD

Leg “B”Azimuth 197°

Leg “A”Azimuth 48°

KOP = 1040 m

KOP = 1054 m

MD = 1435 mDev = 90.6°TVD = 1102

MD = 1421 mDev = 89.3°TVD = 1106

Open Hole 6 1/8” Open Hole 6 1/8”Casing 3 1/2”

CASING 7” - N80

240 m 311m

- South America


Well Planning- Drivers

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

Optimize well costsOptimize well productivityOptimize life-cycle operating expense


Summary

You should now be able to:List typical and describe completion techniques for vertical, deviated and horizontal wellsList advantages and disadvantages for the completion techniquesDescribe typical completion procedures

Documents

01-Reservoir 02-Well Completion Methods