Transcript of Gas Exploration Team Hail 7 Casing Design. Overview Wellbore Schematic Design and load assumptions...
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- Gas Exploration Team Hail 7 Casing Design
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- Overview Wellbore Schematic Design and load assumptions Design
Factors Casing Strings & Connections Details Minimum Safety
Factors Yield Envelopes with Tasks Loads Production Tubing Movement
Production AFE Safety Critical Moments (SCM) Safety Critical
Moments (SCE) Operational Mitigations
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- Wellbore Schematic
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- Design and Load Assumptions Based on team discussions (Hassan
Abdul Karim, Thein Zaw Phyoe (Schlumberger) the following design
predications were declared: We would have strong probability of and
ability to displace cement to the mudline on every single casing
and we would have TOC to the TOL on every liner string and if we
didnt that it is ADMA policy to remediate. A void sensitivity study
up and down the cement column, to try to spot vulnerabilities to
weakest external pressures to burst loads, found none lacking
adequate margin. Also, we discussed fluid drop and that fluid drop
inside of 20 casing would be used and this load is resisted by the
casing resistance within acceptable margins.
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- Design Factors Based IPR 1.8 Sour Critical Drilling Axial1.6
Burst1.25 Collapse1.0 Von Mises Triaxial Yield Criterion 1.25
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- Casing Strings & Connections Details
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- Minimum Safety Factors
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- Yield Envelopes with Tasks Loads
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- Production Tubing Movement 5-1/2 tubing stays within the 20 up
and down stroke of the expansion packer
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- Production AFE
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- Safety Critical Elements (SCE) Safety Critical Element Any
component part of structure, equipment, plant or system whose
failure could cause a major accidentt. Source: API RP 2FB,
Recommended Practice for the Design of Offshore Facilities Against
Fire and Blast Loading, First Edition, April 2006. Global
StandardsAPI
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- Safety Critical Elements (SCE) Foundation Cement of 30 and 20
BOPE Cementing/sealing off Arab H 2 S gas Cementing/sealing off
Khuff/PreKhuff H 2 S gas Acid Frac job equipment high pressures
Corrosive elements Production testing/buildup tubing and equipment
high pressures H 2 S Hydrogen Embrittlement -stresses AFE and AFC
strains
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- Safety Critical Elements (SCE) In regards to the wellhead
hanger and flange for the 9-5/8 casing this is at a critical point
because the bullhead load our casing is good for while drilling the
pay zones in 8-3/8 looks like this at the surface: As we can see in
the table the internal pressure is 10,008.47 psi which is indeed
just over 10K. For reference we can also see the 1800 psi backup
pressure we will need during this bullhead well control procedure
to keep the 9-5/8 casing from bursting just below the wellhead and
creating a disaster scenario. We simply need to confirm that while
drilling the 8-3/8 section that the working pressure wellhead
hanger and flange will be 15K and the 10,008.47 psi drilling load
safely within this operational resistance envelope.
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- Safety Critical Moments (SCM) Safety Critical Moment Any
component part of the wellbore construction timeline in which a
hazard level is at a peak elevation or maximum rate of increase and
human factor components of the control system must recognize this
in order to appropriate response levels and structural mitigations.
Source: Michael Davis, Petroleum Engineer
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- Safety Critical Moments (SCM) Cement job of 30 and 20 because
this is the foundation of the well. Drilling the Arab sands because
of H 2 S Cementing casing around the H 2 S gas Drilling the Khuff
and Pre-Khuff sands because of H 2 S. Cementing casing around the H
2 S gas Fracture stimulation job with all of the high pressures
Production testing/buildups - high pressures - H 2 S and stresses
of the AFE and AFC strains.
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- Operational Mitigation
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- During this Full Column of Arab H 2 S Gas Bullheading operation
the Triaxial Safety Factors would fall below standard as seen in
the figure below:
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- Operational Mitigation
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- And yet we cannot add a higher weight because the ID would not
pass our 12 bit and a higher grade would not resist the hydrogen
embrittlement load during this exact H 2 S Acid Gas Kick Bullhead
we are modelling so we can add backup pressure to the C annulus
this time. The backup pressure that works is 440 psi and yet we
must add 1 psi of C annulus pressure for every 1 psi of Bullhead
pressure that exceeds 5450 psi pump pressure (ie. If Bullhead
pressure is 5400 psi there is not a need to add C annulus backup
pressure yet if it reaches 6000 psi we must add (6000-5450=550) 550
psi to the C annulus. The anticipated max pressure will be 5900 psi
bullhead pressure so 440 psi C annulus pressure will be
sufficient.
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- Operational Mitigation
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- Similar to the Kick from Arab inside 13 if a kick is taken in
the 9 that creates maximum bullhead pressure of 10,000 psi will
require injecting 1800 psi of fluid pressure into 13 x 9 (or 1 psi
of annular fluid pressure for every 1 psi of 9 casing pressure
above 8,000 psi) annulus to prevent the 9 tie- back from exceeding
yield and failure stresses.
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- Operational Mitigation
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- Production Test Tubing Mitigation Production Test Tubing 0-3000
lowered temperatures, high axial tension & environment
conducive to condensation & moisture creating acidic
environment causal in pitting and hydrogen embrittlement attack of
test tubing: T95
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- Production Test Tubing Mitigation
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- In mitigating the lowering of the surface temperature during a
buildup test and the hydrogen embrittlement attack on tubing that
could fail the ONLY REMAINING BARRIER with cascading failures of
casing just under the wellhead we will be balancing a loss in
Axial, Burst and Collapse resistance for more H2S resistance as
seen in the above figure.
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- Production Test Tubing Mitigation
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- Production AFE AFE MANAGEMENT There are many ways to manage
this AFE and they include: Displace the annuli with appropriately
weighted insulated fluid Bleed the pressure off with a carefully
designed pressure schedule to ensure leaks are detected if they
develop. Put a gas cushion designed to displace a minimum of the
Incremental AFE Volume into each annulus before production. A
combination of 1,2,3
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- Production AFE Mitigation