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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