0915 Oil and Gas UK Guidelines J Schoenmakers Shell OGUK W
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Transcript of 0915 Oil and Gas UK Guidelines J Schoenmakers Shell OGUK W
The 2009 Issue of the The 2009 Issue of the
Oil & Gas UK Guidelines for the Oil & Gas UK Guidelines for the
Suspension and Abandonment of WellsSuspension and Abandonment of Wells
By Jules Schoenmakers,Shell EP Europe on behalf of
Oil & Gas UK Decommissioning Work Group 4b
SPE Well Abandonment 2009 Conference
30th June 2009, Aberdeen Exhibition and Conference Centre
• Jules Schoenmakers (Shell), Workgroup Chair
• Colin McDonald Smith, Phil Keeble (BP)
• Jean Marie Prieur, Peter Irvine (ConocoPhillips UK Ltd)
• Max Baumert, Richard Cutt (ExxonMobil International Ltd)
• Iain Sutherland, Giancarlo Pia (Talisman Energy (UK) Ltd)
• Garry Skelly (Sigma Wellservice Ltd)
• Donald Dobson (Health and Safety Executive)
• David Soden, Francois Rodot, Michel Bouillet (Total E&P UK)
• Frank Calder, Bob Beagrie (Schlumberger UK)
• Colin Wight (Halliburton UK)
• Steve Kirby (Sasok Ltd), Technical Author
Oil & Gas UK Workgroup 4b membersOil & Gas UK Workgroup 4b members
The contributions of the members and numerous external review parties are very much acknowledged.
• Guidelines assist compliance with the UK Offshore Installations and Wells Design and Construction Regulations, DCR 13, 15 and 16.
• DCR requires Operators to prevent, on a permanent basis, escape of fluids from the well.
• The Guidelines provide minimum criteria to ensure isolation of formation fluids both within the wellbore and from surface or seabed.
• It is accepted that reducing risk to As Low As Reasonably Practicable (ALARP), as required by Regulations, can be demonstrated by best practice.
• Operators expected to develop ‘in-house rules’ for their own operations.
The context of the GuidelinesThe context of the Guidelines
Key changes to GuidelinesKey changes to Guidelines
� Improved structure, streamlined & improved graphics
� Barrier principle and best practices highlighted
� Combination barrier introduced
� Annulus cement requirements clarified
� Liner lap, Cut casing requirements clarified
� Verification: Pressure testing in relation to a leak path below the cement.
� Established list of data for abandonment design
� Excluded Carbon Dioxide sequestration issues since experience is too sparse to define Guidelines.
� Declined to define guidelines for surface plugs, fluid injection, NORM treatment , explosives, well construction.
Permanent Abandonment Barrier schematicPermanent Abandonment Barrier schematic““Restoring the Cap RockRestoring the Cap Rock””
Barrier Elements
Height of 500ft MD, containing at least 100ft MD of Good Cement.
Plug Depth determined by formation (impermeability and strength) and primary cementation
Best Practices
Pipe stand-off
Good bond, clean surfaces, water wet
Support to prevent cement movement, slumping and gas migration while setting
Sealing Abandonment plug
Casings, tubing embedded in cement
Sealing primary cementations
Formation:Impermeable &adequate strength to contain future pressures
Tubing sealed with cement, in cement
Barrier Elements
Height of 500ft MD, containing at least 100ft MD of Good Cement.
Plug Depth determined by formation (impermeability and strength) and primary cementation
Best Practices
Pipe stand-off
Good bond, clean surfaces, water wet
Support to prevent cement movement, slumping and gas migration while setting
Sealing Abandonment plug
Casings, tubing embedded in cement
Sealing primary cementations
Formation:Impermeable &adequate strength to contain future pressures
Tubing sealed with cement, in cement
Need for cement plug support Need for cement plug support
Thin mud Thick mud Vertical hole (helix)
Mud rheology typically cannot support a cement slurry with significant density
difference; moving and contaminated cement will not provide a proper barrier
Slurry
SlumpingResults in
poor plug
Materials for Permanent barriersMaterials for Permanent barriers
� Very low permeability
� Long term integrity
� Non-shrinking� Ductile, not brittle
� Able to bond to casing or formation� Resistant to downhole fluids and gasses,
e.g. CO2, H2S
Cement is accepted as the prime material, but does not preclude others.
Materials in packers, bridge plugs, electrical cables, hydraulic lines are not acceptable as permanent barrier.
Minimum number of barriers requiredMinimum number of barriers required
One permanent barrier above a distinct permeable formation, as a minimum.
Two barriers if a permeable formation is - overpressured, or
- hydrocarbon bearing. Placement of two barriers may be combined; next
slide.
Open-hole needs barrier across the last shoe,
and open-hole barriers if shoe strength inadequate
Dual or Combination barriers, Cased holeDual or Combination barriers, Cased hole
Dual Barrier Solution
Plug should each contain >100ft of Good Cement. Each
typically 500ft long.
Annulus should
contain >100ft Good Cement opposite each internal plug.
Combination Barrier Solution
Plug should contain
>200ft of Good Cement. Typically 800ft long.
Annulus should contain
>200ft Good Cement opposite the internal plug
Figure 3 Comparison of Length of Dual or Combination Barriers
Dual Barrier Solution
Plug should each contain >100ft of Good Cement. Each
typically 500ft long.
Annulus should
contain >100ft Good Cement opposite each internal plug.
Combination Barrier Solution
Plug should contain
>200ft of Good Cement. Typically 800ft long.
Annulus should contain
>200ft Good Cement opposite the internal plug
Figure 3 Comparison of Length of Dual or Combination Barriers
>1000 ft if not logged
>1000 ft if not logged
Strengths and WeaknessesStrengths and Weaknesses
More operational & safety risk
Higher costIf plug fails, more remedial work
1st plug can affect the placement of
the 2nd (thru-tbg case stringers)
Higher risk of swabbing in small hole
(stinger set plug)
Smaller volumes, higher risk of
contamination
Higher risk of slumping and/or losses
WeaknessesWeaknesses
If plug fails less remedial workLower cost
More flexibility with positioningLower contamination, larger volume
1st plug can provide support for 2ndMore good cement in plug
Redundancy, independence
(although errors can be reproduced)
Reduced operational & safety risk
StrengthsStrengths
Two distinct barriersTwo distinct barriersCombination barrierCombination barrier
Open hole abandonmentOpen hole abandonment
Primary Barrier to Zone A, if Potential Internal Pressure exceeds
shoe fracture pressure.
Minimum100ft Good Cement,
typically 500ft MD
Figure 4A Example Open Hole Permanent Barriers
(If Potential Internal Pressure exceeds the casing shoe fracture pressure)
Zone A Zone A
SecondaryPermanent
Barrier to Zone A required
to fully seal the open hole
section.
Minimum 100ft Good
Cement, typically 500ft MD
Primary Barrier to Zone A, if Potential Internal Pressure exceeds
shoe fracture pressure.
Minimum100ft Good Cement,
typically 500ft MD
Figure 4A Example Open Hole Permanent Barriers
(If Potential Internal Pressure exceeds the casing shoe fracture pressure)
Zone A Zone AZone A Zone A
SecondaryPermanent
Barrier to Zone A required
to fully seal the open hole
section.
Minimum 100ft Good
Cement, typically 500ft MD
Primary Barrier to Zone A
At least 100ft MD of Good Cement into casing shoe, typically 500ft MD
Secondary Barrier to Zone AAt least 100ft MD of Good Cement into casing shoe, typically 500ft MD Single Barrier to Zone A
Minimum 200ft of Good Cement into casing shoe, typically 800ft MD
Dual Barrier SolutionCombination Barrier Solution
Figure 4B Example Open Hole Permanent Barriers
(IfPotential Internal Pressure does notexceed the casing shoe fracture pressure)
Zone A Zone A
Primary Barrier to Zone A
At least 100ft MD of Good Cement into casing shoe, typically 500ft MD
Secondary Barrier to Zone AAt least 100ft MD of Good Cement into casing shoe, typically 500ft MD Single Barrier to Zone A
Minimum 200ft of Good Cement into casing shoe, typically 800ft MD
Dual Barrier SolutionCombination Barrier Solution
Figure 4B Example Open Hole Permanent Barriers
(IfPotential Internal Pressure does notexceed the casing shoe fracture pressure)
Zone A Zone AZone A Zone A
Weak zone
Verification of permanent barriersVerification of permanent barriers
• Verification requirements are highly dependent on individual well and job design, but any permanent barrier should be verified forrequired depth and sealing capability.
• Methods: Slurry strength development, job records, tagging, weight testing, pressure testing, inflow testing.
• Tagging and pressure testing is the standard approach. Test pressure at least 500 psi over injection pressure below barrier, however without damage to casing or primary cementation.
• No pressure test is required if cement plug placed on a tagged and pressure-tested mechanical plug or on a cement plug, provided no job anomalies.
• Annulus cement: log, original job records, absence of sustainedcasing pressure, initial formation strength test
DocumentationDocumentation
• Statutory Notifications DECC, HSE, DEAL, Hydrographic Office, Oil & Gas UK, Kingfisher
• Record keeping Job records, verification, status diagrams, wellheads, Upload toCDA database
Final remarksFinal remarks
• An effective and efficient well abandonment starts at a
sound well design (e.g. casing setting depths, top of cements, packer setting depth, control lines, no annulus
top-ups, overburden gas coverage, etc)
• Next update of the Guidelines scheduled for 2012. Workgroup will work a number of long-lead issues in the
mean time.
Thank you for your attention