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Copyright 2008, NExT, All rights reserved
Well CompletionTechniques
Copyright 2008, NExT, All rights reserved
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
Copyright 2008, NExT, All rights reserved
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
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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
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Well Completion Techniques
Open hole
Liner (cemented, slotted or perforated)
Cased hole
Tubingless or Slimhole
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Open Hole (Barefoot) Completion
New reservoir
Casing
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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
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Liner Completions
Slotted orperforated Permanent
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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
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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
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Cased Hole
Oil or gasreservoir
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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
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Tubingless or Slimhole
Oil or gasreservoir
Two to three strings can berun for multiple completions
Smaller diametertubing string
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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
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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
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Well Completions (Vertical Wells)
Single Zone
Multiple Zones
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Single Zone Completion
* Single zone completion - One reservoir is producing.
Open-ended Packer
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Multiple Zone Completion* Multiple zone completion - More than one reservoir is
producing.
Open - ended(Commingled) Dual packer
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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.
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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
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Horizontal Wells
Required new/modified completion equipment or techniques
Zonal isolationPlacement of equipment in horizontalStimulation techniquesPerforatingProduction loggingIntervention Issues
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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
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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
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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
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4 1/2” tubing
Packer SC-1LRSeal borereceptacle
Bull plug
0.040” slotted liner0.012” pre-packedslim pak screens
West Africa - Horizontal Well
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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
Copyright 2008, NExT, All rights reserved
IT 4447485
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Considerations
Type of formationHomogeneousHeterogeneousNaturally Fractured
Type of wellOil or gasNear oil/gas contact or oil/water contact
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Homogeneous Formation
Easy to accommodate completion designGenerally requires little isolation of zonal segmentsWell adapted to openhole completion if reservoir is competent
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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
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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
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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
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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
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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
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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
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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
Copyright 2008, NExT, All rights reserved
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