Download - CNRL Presentation Feb 19
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Thermal Wells: Abandonment & Remediation
Will Butler, P.EngTeam Lead - Engineering
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Topics Brief overview of Directives, Regulations & IRP’s
Common Compliance Issues
Well Case Studies
4 wells located within thermal development area
1 well located outside thermal development area
1 with a liquid SCVF
1 with a potential gas migration
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FundamentalsUnderstand current directives, regulations and IRP’s
AER Directive 009 – Minimum Casing Cementing Requirements Sec. 3.2 – Surface Casing
Sec. 3.3 – Production, Intermediate & Liner Casing
Sec. 4.2 – Thermal Cement
Sec. 5 – Method of Determining Required Cement Top
AER Directive 010 – Minimum Casing Design Requirements
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FundamentalsUnderstand current directives, regulations and IRP’s
AER Directive 020 – Well Abandonment Sec. 4.2 – Open-Hole Abandonment in Penetrated Oil Sands Zones
Sec. 4.6 – Oil Sands Evaluation Wells & Test Hole Wells
Sec. 5.4 – Cased Wells Penetrating Oil Sands Zones
Sec. 5.5 – Groundwater Protection
Sec. 7.0 – Testing & Inspection Requirements for GM & SCVF
ID 2003-01 Sec. 2 – SCVF/GM Testing, Reporting & Repair Requirements
Sec. 3 – Casing Failure Reporting & Requirements
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FundamentalsUnderstand current directives, regulations and IRP’s
IRP Volume 03 – In Situ Heavy Oil Operations
Required assessment of offset, abandoned/vintage well & neighbouring operator wells for compatibility to thermal operations:
Within 300m of SAGD & 1000m of CSS developments.
Wells which operator deems a risk factor or by request of landowner
Describes mechanical considerations due to thermal & pressure cycling:
Casing loads (stress & strain)
Corrosion considerations
Coupling suitability
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FundamentalsUnderstand current directives, regulations and IRP’s
IRP Volume 03 – In Situ Heavy Oil Operations
Describes cementing considerations:
Hydraulic Isolation (Porous & Groundwater)
Caprock/primary seal integrity
Cement type & integrity evaluation
Strength retrogression at operating temperature
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Common Compliance Issues Well is not properly isolated with thermal cement across oil sands
formations
• Primary cement
• Wellbore cement plugs (openhole or cased)
Existing primary cement integrity is unknown or in question
• Unsuitable for expected temperature & pressure cycling?
• Temperature degradation of non-thermal cement?
• AER generally requires a CBL run before further approval of operations
Casing failure/corrosion issues present
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Common Compliance Issues Abandonment was not to current D020 standards
Casing/connections not suitable for potential thermal and pressure cycling stresses
• Non-premium connections
• Mechanical properties deemed unsuitable by engineering assessment or physical testing
SCVF/GM exists• Liquid SCVF’s are usually “severe” due to high salinities & trace hydrocarbons
• Gas SCVF’s are usually “non-severe” due to flow rate less than 300 m3/d
• GM’s are rare, but observed from time to time
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Case 1: Background Vertical well east of Fort McMurray
Rig Release: February 1981
Zonally abandoned and well cut and capped
Compliant in 1981
Currently within 100m of a proposed steam injection well
Max. temperature = 235oC
Max. Pressure = 4MPa
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Case 1: Compliance ConsiderationsSurface cement plug
Prod. casing/connections are inadequate for expected temperatures
Cemented with Class G with no returns to surface
BP capped with Class G
Non-routine waiver submitted to leave wellbore as is and operate as an observation well
Approval rejected, well must be made thermally compliant due to steam chamber proximity
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Case 1: OperationsStep 1: Drill out surface plug & BP
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Case 1: OperationsStep 1: Drill out surface plug & BP
Step 2: Run CBL/VDL to verify cement top and integrity across non-
thermal formations to 109mKB
TOC 25m above sfc. csg shoe
Cement bond is good throughout
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Case 1: OperationsStep 1: Drill out surface plug & BP
Step 2: Run CBL/VDL to verify cement top and integrity across non-thermal formations to 109mKB
Step 3: Section mill & under-ream casing & cement from 109mKB to below shoe @ 298mKB
AER Oilsands interval requiring thermal isolation
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Case 1: OperationsStep 1: Drill out surface plug & BP
Step 2: Run CBL/VDL to verify cement top and integrity across non-
thermal formations to 109mKB
Step 3: Section mill & under-ream casing & cement from 109mKB to
prod. csg. Shoe @ 298mKB
Step 4: Spot continuous thermal cement plug from TD to min. 15m
above sfc. csg. shoe
Estimated Cost = $450,000.00
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Case 2: Background Vertical well NW of Cold Lake
Rig Release: March 1965
Perfs just below the Grand Rapids formation top
Openhole section abandoned in 1965
Grand Rapids perfs abandoned in 2001
Well within 200m of proposed steam chamber targeting the Clearwater Group
Max. Temperature = 180oC
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Case 2: Compliance ConsiderationsCasing cemented to surface with thermal cement with good returns to surface (verified by CBL)
Bridge plug set within 15m of Grand Rapids perfs & capped with 10m of thermal cement
Thermal cement plug set in OH section and across shoe from 434.0-372.2mKB in 2001
Non-thermal cement plug set in OH section from TD to 434.0mKB in 1965
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Case 2: Operations AER non-routine waiver to leave wellbore “as
is”, approved on the grounds that:
1. Above 434.0mKB, well is essentially thermally compliant
2. Clearwater formation (target zone) is isolated with thermal cement and well above non-thermal cement plug from TD to 434.0mKB
No remedial operations required
Cut & cap well
Estimated cost = $8,000.00
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Case 3: Background Vertical well North of Cold Lake
Rig Release: November 1985
Corehole well with no surface casing
Cement plugs placed before rig release in 1985.
Well is located within 50m of a proposed steam chamber targeting the Clearwater formation
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Case 3: Compliance ConsiderationsThermal cement plug top is located 17.4m above Grand Rapids formation top
Formations above the Mannville Group require isolation
• Joli Fou
• Viking
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Case 3: Operations AER non-routine waiver to leave
wellbore “as is”, approved on the grounds that:
1. Clearwater formation (target zone) is isolated with thermal cement
2. OH logs indicate absence of porosity across the Joli Fou & Viking formations
3. Difficulty associated with attempting to drill out surface OH cement plug
No remedial operations required
Estimated cost = $0.00
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Case 4: Background Vertical well south of Fort McMurray
Rig Release: January 2000
Perfs @ McMurray, Wabiskaw & Clearwater formations
Well is within proposed steam chamber targeting the McMurray
Client concerned casing may part due to thermal stress created by possible steam chamber contact
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Case 4: Compliance Considerations
Prod. casing/connections are inadequate
Casing cemented to surface with non-thermal thixotropic cement with good returns to surface (verified by CBL)
Non-routine waiver submitted to AER with an engineering assessment of casing stress/strain and cement integrity from expected steam chamber operations
AER approved the following operations
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Case 4: OperationsStep 1: Remove 38.1mm coil tubing
strings and retrieve Packer @ 407mKB
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Case 4: OperationsStep 1: Remove 38.1mm coil tubing
strings and retrieve Packer @ 407mKB
Step 2: Retrieve WR plug @ 416mKB
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Case 4: OperationsStep 1: Remove 38.1mm coil tubing
strings and retrieve Packer @ 407mKB
Step 2: Retrieve WR plug @ 416mKB
Step 3: Chemically cut casing in the McMurray formation
@ 460mKB
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Case 4: OperationsStep 1: Remove 38.1mm coil tubing
strings and retrieve Packer @ 407mKB
Step 2: Retrieve WR plug @ 416mKB
Step 3: Chemically cut casing in the McMurray formation
@ 460mKB
Step 4: Run & set BP @ 459mKB
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Case 4: OperationsStep 1: Remove 38.1mm coil tubing
strings and retrieve Packer @ 407mKB
Step 2: Retrieve WR plug @ 416mKB
Step 3: Chemically cut casing in the McMurray formation
@ 460mKB
Step 4: Run & set BP @ 459mKB
Step 5: Spot continuous thermal cement plug from TD to min. 15m
above sfc. csg. shoe
Estimated Cost = $90,000.00
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Case 5: Background Vertical well north of Red Earth Creek
Rig Release: March 1995
Openhole section penetrates the Bluesky Formation
Well is not located within, or near, a proposed thermal development
Very little bitumen present in formations in this area
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Case 5: Compliance ConsiderationsProd. casing/connections inadequate?
Casing cemented to surface with Class G cement with good returns to surface (verified by CBL)
AER non-routine procedure was approved based on the following:
1. Very little to no bitumen in formations from OH logs
2. Unlikelihood of a thermal project developing in the area
Condition: Should thermal operations develop within vicinity of the well, it must be remediated to a state that AER deems “thermally compatible”
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Case 5: OperationsStep 1: Retrieve 60.3mm tubing
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Case 5: OperationsStep 1: Retrieve 60.3mm tubing
Step 2: Spot continuous thermal cement plug from TD to surface
Estimated cost = $35,000.00
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Case 6: Background Vertical well north of Cold Lake
Rig Release: March 2013
Well has an existing liquid SCVF issue (~500ml/day)
From offset activity, likely source from the 2nd White Specks
Two cement squeeze attempts at 2WS were unsuccessful
Previous logs indicate excellent caprock at the surface casing shoe
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Case 6: Compliance Considerations Casing designed with premium connections
Production casing cemented to surface with thermal cement (Verified with CBL)
Only 10m between squeezed abrasive slots and surface casing shoe with no caprock
2WS source is well above the Grand Rapids formation
Non-thermal cement may be used
Non-routine waiver submitted to AER to access caprock at surface casing shoe & perform remedial cement squeeze
AER approved the following operations:
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Case 6: Operations Drill out cement plug to ~5m below surface
casing shoe
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Case 6: Operations Drill out cement plug to ~5m below surface
casing shoe
Perform six 120o Abrasive cuts from 172-174mKB
Establish feed rate into abrasive slots at a maximum of 3.1MPa (fracture gradient)
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Case 6: Operations Drill out cement plug to ~5m below surface
casing shoe
Perform six 120o Abrasive cuts from 172-174mKB
Spot a Non-thermal cement plug from 178mKB to surface
Squeeze cement to a maximum of 3.5MPa
Estimated cost = $160,000.00
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Case 7: Background Vertical well east of Christina Lake
Rig Release: March 2012
Well has an existing GM issue
Drilling reports indicated significant gas at the McMurray formation top
Confirmed by original OH & neutron logs
Review of nearby wells revealed a gas injector belonging to another operator
Injector was maintaining a gas cap in the Wabiskaw/McMurray formation
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Case 7: Compliance Considerations Openhole cemented to surface with thermal
cement, but placement method is unknown
Balanced, staged, layered, etc.?
Openhole caliper log indicates significant wellbore deviation from McMurray formation to surface
Cement to formation bond is likely very poor
Proposed intervention interval is 50m above the Grand Rapids formation
Non-thermal cement may be used
High risk in attempting to drill out OH cement plug in order to target McMurray source
AER waiver required for well re-entry
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Case 7: Operations Install new wellhead and SCVF assembly &
confirm if leak is a SCVF or GM
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Case 7: Operations Install new wellhead and SCVF assembly &
confirm if leak is a SCVF or GM
If possible, shut in injector well & allow stored gas to migrate & dissipate
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Case 7: Operations Install new wellhead and SCVF assembly &
confirm if leak is a SCVF or GM
If possible shut in injector well & allow stored gas to migrate & dissipate
Drill out cement in surface casing to 25m below the shoe
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Case 7: Operations Install new wellhead and SCVF assembly &
confirm if leak is a SCVF or GM
If possible shut in injector well & allow stored gas to migrate & dissipate
Drill out cement in surface casing to 25m below the shoe
Under-ream a minimum of OH diameter (or greater) to within 1-2m of casing shoe
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Case 7: Operations Install new wellhead and SCVF assembly &
confirm if leak is a SCVF or GM
If possible shut in injector well & allow stored gas to migrate & dissipate
Drill out cement in surface casing to 25m below the shoe
Under-ream a minimum of OH diameter (or greater) to within 1-2m of casing shoe
Spot continuous thixotropic or expanding cement blend from PBD to min. 15m above the sfc. csg shoe (no squeeze)
Estimated cost = $240,000.00
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In Conclusion
Know and understand applicable regulations & IRP’s for oilsands & thermal development areas
Confirm status & condition of wells, including proximal & those of offset operators, near thermal development areas
300m from SAGD operations
1000m from CSS operations
Generally, a well is not thermally compliant unless all requirements in the directives are met
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In Conclusion
Wells may receive AER approval to abandon with alternative methods, if an engineering assessment supports long term integrity of the well
Physical Testing
Numerical Analysis
Computer simulation of temperature & pressure effects
Historical case studies in comparable areas
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Questions