© 2015 Cairn India Limited
Rigless Well Abandonment
OISD Workshop 28th & 29th Dec 2016, Noida
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Outline
Permanent Well Abandonment – Overview
Global P&A Standards - Comparative Analysis
Rigless P&A
Outline procedure
Compliance with standards
Advantages and Limitations
Case Study
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Permanent Well Abandonment – Overview
Why?
Prevent hydrocarbon leak on surface
Isolate permeable zones to prevent crossflow
Prevent contamination of freshwater aquifers
Enable removal of mechanical installation below surface / seabed
Regulatory requirement for site restoration
Applicable
Exploration or Appraisal Well
End of economic life
Not operated / required for the purpose
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Permanent Well Abandonment – Overview
Critical Requirement Prior to P&A
GL or
MLS
Cement top cover the previous casing
Surface
Csg shoe
Good cement bond at least 100 m above
and below porous zone
Intermediate
Csg
Multiple permeable zones have good
cement above and below
Prod. Csg Surface casing is cemented upto surface
100 m
100 m
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Permanent Well Abandonment – Overview
GL or 60 m length P&A Requirements – Open Hole
MLS
Cement plug across hydrocarbon zone
Surface
Csg Cement plug across casing shoe OR
Drilling Fluid
Bridge plug 15-30 m above casing shoe
Intermediate
Csg
30 m Above &
Squeeze cement across casing failure
Below
Perforate Prod & Intermediate Casing to
Prod. Csg 30 m Above &
Below
place 50m of cement in both annuli
Drilling Fluid Recover casings
30 m Above & Surface plug of 60m below GL / MLS
Below
Pressure test and Weight test the cement
plugs. Fill up the well with drilling fluid
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Permanent Well Abandonment – Overview
GL or
MLS
60 m length P&A Requirements – Cased Hole
Cement plug across hydrocarbon zone
Surface
Csg Spot cement above completion packer
Drilling Fluid
Isolate liner lap with cement plug across
Intermediate
the top of liner and inside
Csg Isolate packer or
liner lap Perforate Prod & Intermediate Casing to
place 50m of cement in both annuli
Prod. Csg
Recover casings and conductor
Drilling Fluid
Surface plug of 60m below GL / MLS
30 m Above &
Below
Pressure test and Weight test the cement
plugs. Fill up the well with drilling fluid
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Global P&A Standards
• Bureau of Safety & Environmental
USA Enforcement (BSEE) - Decommissioning
Guidance
• Oil & Gas UK – Guidelines for
UK suspension and abandonment of wells
• NORSOK standard D-010 - Plugging,
Norway abandonment and suspension
• Oil Industry Safety Directorate (OISD)
India STD-175 - Well Abandonment
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Global P&A Standards – Verification of Barriers
BSEE NORSOK D-10
Weight Test – 15000 lbs Tag test
Pressure Test upto 1000 psi Pressure Test upto 500 psi above
Inflow Test LOT
** BSEE has recognized Weight test is Inflow Test
not feasible in Rigless operations
O&G UK OISD
Weight Test – 10 to 15000 lbs (Tag Weight Test 8 MT (17600 lbs)
test with wireline / CT is acceptable) Pressure Test 500 PSI or 80% of LOT
Pressure Test upto 500 psi above for Open Hole
LOT Pressure Test 1000 psi for cased hole
Inflow Test ** OISD recognizes not doing weight test
on case to case basis
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Global P&A Standards – Rigless P & A
BSEE
BSEE recognizes Rigless Abandonment with recommended procedure:
Circulate and Squeeze cement plug across permeable zones
Place balanced plug inside tubing and annulus by circulation into annulus
Cut and retrieve tubing from 150-300m
Place balanced plug across annuli to facilitate casing cutting and retrieval
O&G UK
O&G UK recognizes Rigless Abandonment with following risk assessment:
Slumping of Cement due to deviation / eccentricity / radial clearances
Reliable verification of cement plugs inside tubing and annulus
Inconclusive wireline tag due to contaminated cement debris in tubing
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Global P&A Standards – Rigless P & A
NORSOK D-10
Indirect reference to Rig-less P & A - Removal of downhole equipment is not
required if barrier requirement is met
Recommends that methods should be established to install and verify position
of plugs
OISD STD 175
Consideration is given to rigless abandonment after proper risk assessment
based on the proposal
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Rigless P&A – Outline Procedure
Establish injectivity into formation
GL or
MLS Pump calculated volume to cement to
Surface squeeze into formation
Csg
Drilling Fluid
Set bridge plug below packer depth
Perforate above packer
Intermediate
Csg Circulate and place cement plug on top of
packer
Prod. Csg Set bridge plug to appropriately place
Drilling Fluid surface plug
Squeeze Plug Perforate tubing and casing
Circulate and pump surface plug
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Rigless P&A - Outline Procedure
Cut tubing and casing above surface plug
GL or
MLS
Recover the Surface equipment X-Mas
Surface
Csg Tree, Wellhead etc
Drilling Fluid
Recover the tubing and casing with simple
lifting equipment
Intermediate
Csg
Prod. Csg
Drilling Fluid
Squeeze Plug
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Rigless P&A - Compliance with Standards
GL or
60 m length MLS
Drilling Fluid Surface Csg Drilling Fluid
Intermediate Csg
Isolate packer or
liner lap
Production Csg
Drilling Fluid Drilling Fluid
30 m Above &
Below Squeeze Plug
Abandonment Requirement Rigless Abandonment
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Rigless P&A – Advantages & Limitations
Advantages
Extremely Cost Effective – Multifold reduction in cost
Applicable to wide range of wells
Meets most of the well abandonment requirements
Minimum footprint
Faster project delivery
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Rigless P&A – Advantages & Limitations
Limitations
Not applicable to ALL the wells – Wells with complication, multilaterals,
horizontals
Weight test is not feasible
Limitations with verification of cement plug position specially in the annulus
Cement settlement along lower side in high angles wells
Cement plug integrity becomes questionable in presence of umbilicals
Requires better precision for cement calculations
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Rigless P&A – Advantages & Limitations
Hydraulic Work-
over Unit (HWU)
Coil Tubing unit
Downhole Complexity
Slickline and
Wireline
Unit
Cost of Abandonment
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Rigless Abandonment: Case study of onshore gas well
Well summary and status before permanent abandonment
X-mas tree 3-1/8” 5K WOM X-mas tree installed on 7-1/16" x 3-1/8" 5K bonnet assembly
BHEL make conventional wellhead system
Wellhead Casing Head Spool: 11" 5k top flange x 9.5/8" Casing (Slip-on weld),
Tubing Head Spool: 11" 5k bottom flange x 7-1/16" 5k Top Flange
Tubing Hanger Tubing Hanger 7-1/16" x 3-1/2" NVAM B with 3" BPV profile
13-3/8” Conductor 13-3/8" K-55 & L-80 68# NSCC @ 114.4 m MDBRT
9 ⅝” Casing 9.5/8" N-80 47# NSCC @ 484.4 m MDBRT
7” Casing 7" 26# K-55 NVAM & BTC @ 0-727 m MDBRT
Upper Completion Single String Single Zone, 2-7/8” 6.5 ppf NVAM tubing
7” WH-6 Retrievable Hydraulic Packer(WFD)@ 540.25 m MD
1.87" F Nipple (Weatherford) @ 560.99 m MD
X-over (2-7/8" NVAM B x 2-7/8" EUE P)
Well Completion
Perforated Pup Joint @ 562.46 m MD
Details
1.82" R nipple (Weatherford) @ 564.36 m MD
4-1/2" 5 spf TCP gun (Confirmed failed to release from Auto release sub)
Shut-in tubing head pressure (THP) is ~640psi
Well was open to following pay zones:
B1c: 592-595 m MDORT, Expected Permeability: 250 md
B1b: 599-608 m MDORT, Expected Permeability: 500 md
B1a: 615-618 m MDORT, Expected Permeability: 350 md
Pay Zones depths
Virgin reservoir pressure ~ 870 psi
& Properties
Depleted reservoir pressure ~ 790 psi (recorded survey in Nov’11)
Depleted reservoir pressure ~ 720- 750 psi (basis – extrapolation from current THP) =
7.45 ppg formation pressure.
Reservoir temperature ~ 60-65°C (last recorded survey)
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Rigless Abandonment: Concept selection and regulatory approval
Dispensation from OISD
Waiver of weight testing
Final Plan,
Risk
assessment, requirement of cement plug set
procurement
inside production casing/ tubing
The bottom most of the two DST
Dispensation zones (909-930m) were not
from OISD
and JV
alignment
isolated from open hole – 200 m
Cement plug was placed from
Rigless abandonment 927 to 727m.
concept selection and
Preliminary Planning
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Rigless abandonment: CB-X-1 well site lay out
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Well Killing and Cementing - Surface line up
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Operations: Well Killing and Plug# 1 placement
Verified integrity of A-annulus & B-annulus
Well killing was planned by bullheading
Packer
Fluid –
13 3/8” casing
shoe at 114m
Attempted to kill the well by pumping kill weight
8.3 ppg
brine multiple times – Observed gas percolation
and subsequent THP build up
9 5/8” casing Placement of viscous pill across the perforations
shoe at 484m
delayed gas percolation
Punched tubing above packer to establish
communication to cater to any contingency during
Plug# 1 placement
Placed cement plug#1 (squeeze plug) from 528 to
618m
Perf: 592 – 618m Verified Plug#1 by pressure test and tag test with
slickline
FC at 684.9m
200 m Plug 7” casing shoe at 727m
8 ½” TD
(727m to 927m)
at 1112m
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Operations: Placement of Cement Plug# 2 & 3 and final P&A
Placed cement plug#2 (displacement plug)
from 425 to 528m in both tubing and A-annulus
13 3/8” casing
shoe at 114m Verified Plug#2 by pressure test and tag test
with slickline
Perforated 2.7/8” tubing and 7” casing from
9 5/8” casing 173.8m - 179.8m
shoe at 484m
Established circulation from tubing side to A-
annulus side
Placed cement plug# 3 from 10m to 180m
Verified the cement plug#3 by pressure test
and tag test with conventional slickline at 10m
Gas cut windows in casing in 9-5/8" X 7", cut 2
Perf: 592 – 618m
7/8" tubing. N/D X-mas tree and wellhead
Fill the half cellar with cement and cover with
soil
FC at 684.9m
200 m Plug 7” casing shoe
8 ½” TD
(727m to 927m) at 727m
at 1112m
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Operations: On site view
