01-Reservoir 02-Well Completion Methods
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Well Completion Techniques
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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
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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 installation Production packer setting Running 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
Casing
New reservoir
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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
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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
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Cased Hole
Oil or gas reservoir
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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
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Tubingless or Slimhole
Smaller diameter tubing string
Two to three strings can be run for multiple completions
Oil or gas reservoir
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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
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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
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Single Zone Completion * Single zone completion - One reservoir is producing. Open-ended
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Packer
Multiple Zone Completion * Multiple zone completion - More than one reservoir is producing. Open - ended (Commingled)
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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.
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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
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Horizontal Wells Required new/modified completion equipment or techniques
Zonal isolation
Placement of equipment in horizontal
Stimulation techniques
Perforating
Production logging
Intervention Issues
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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
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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
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• 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
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• 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
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Homogeneous Formation Easy to accommodate completion design Generally requires little isolation of zonal segments Well adapted to openhole completion if reservoir is competent
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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
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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
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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
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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
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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
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- 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
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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
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