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Gas Lift Challenges - · PDF fileGas Lift Challenges Mike Johnson ... Corporate Separateness Exxon Mobil Corporation has numerous ... Best suited if DP1 is very close to DP 2 DP 2

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  • Gas-Lift WorkshopQatar

    February 4 - 8, 2007

    This presentation is the property of the author(s) and his/her/their company(ies).It may not be used for any purpose other than viewing by Workshop attendees without the expressed written permission of the author(s).

    Gas Lift Challenges Mike JohnsonExxonMobil Production Company

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 2

    Corporate Separateness

    Exxon Mobil Corporation has numerous subsidiaries, many with names that include ExxonMobil, Exxon, Esso and Mobil. For convenience and simplicity in this presentation, the parent company and its subsidiaries may be referenced separately or collectively as "ExxonMobil."

    Abbreviated references describing global or regional operationalorganizations and global or regional business lines are also sometimes used for convenience and simplicity.

    Nothing in this presentation is intended to override the corporate separateness of these separate legal entities. Working relationships discussed in this presentation do not necessarily represent a reporting connection, but may reflect a functional guidance, stewardship, or service relationship.

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 3

    Significant Challenges Operating Gas Lift

    Challenges Highly deviated, extended reach gas lift wells SPM Pre-loading Dual Gas Lift

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 4

    Gas Lift Mandrel w/ orifice valve @ 6600

    meters, MD

    Build angle 1.5 deg per 20 m, EOB ~ 1624 meters Hold angle 75.2 deg

    7 liner 9375 meters MD, 2613 meters, TVD

    7 Production Tubing

    1685 meter, 8.5 horizontal section 9.625 casing at 7690 meters, MD

    Highly Deviated Extended Reach Wells

    Using high pressure gas lift for deep single point of injection

    Have begun running a shallower back up mandrel with a dummy for unloading wells

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 5

    Gas Lift Mandrel w/ orifice valve @ 6600

    meters, MD

    Build angle 1.5 deg per 20 m, EOB ~ 1624 meters Hold angle 75.2 deg

    7 liner 9375 meters MD, 2613 meters, TVD

    7 Production Tubing

    1685 meter, 8.5 horizontal section 9.625 casing at 7690 meters, MD

    Highly Deviated Extended Reach WellsChallenge: Change valve using wireline tractor or coil tubingPositive surface indications of valve setting in pocket

    Maximum KOT and valve latch/body tolerances for push pull forces

    KOT design to assure valve/pocket alignment for setting valve at horizontal angle with pocket on the high side of the tubing.

    Industry experience using CT in horizontal section SPE Paper 60722

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 6

    Preloading of Side Pocket Mandrels

    Reoccurring problems with difficulty or inability to retrieve dummies and valves from side pocket mandrels. Latches and valves may be bent or broken off during wireline operations.

    Some equipment may be installed at the rig location rather than in a shop.

    No common or recommended procedure within the industry to insert the device into the pocket in the shop prior to running in the well.

    Where feasible, we have begun running more live valve strings on initial completion to reduce number of wireline jobs required to place well on gas lift.

    We need an industry Best Practice for pre-loading side pocket mandrels.

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 7

    Shop modified KOT for latching bent valve

    Valve in pocket bent to 40 deg. angle

    Bent Valve in pocket

    KOT welded angle extension to reach

    out and go over bent latch

    KOT extension designed to

    straighten latch during jar down

    operation

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 8

    Dual Gas LiftUsing High Pressure Gas Lift for single point of injection

    Shear Orifice Valve failure

    Consider running a back up mandrel

    Challenge: Change valve using wireline tractor or coil tubing

    Definition: Dual gas lift is defined as using gas-lift in both sides of a dual completion with gas lift supplied through same tubing-casing annulus.

    Does not include:

    If one side is flowing naturally and not equipped with gas lift valves.

    If one side is not a liquid producer (eg: water injector, gas injector, gas producer).

    If one side uses macaroni string for gas lifting.

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 9

    Dual Gas LiftUsing High Pressure Gas Lift for single point of injection

    Shear Orifice Valve failure

    Consider running a back up mandrel

    Challenge: Change valve using wireline tractor or coil tubing

    Dual gas lift is most effective if the producing zones are similar in reservoir characteristics. Experienced difficulties in wells when one producing string is only about 10 15 % of the other string.

    Difficult to achieve and maintain the optimum injection rate to both strings

    Inject at optimum rate

    Severe production heading or fluctuations that may be caused by unsteady or fluctuating injection at the downhole operating point can lead to significant inefficiency in gas lift operation.

    Inject in a stable manner.

    Lower producing zones always suffer as top packer needs to be set above the top zone. Hence, the deepest mandrel is still too far from the zones.Use of insert string can improve the injection point in the lower zone.

    Inject as deep possible in both sides.

    Very often one side robs all the gas.Low PI zones have very low flowing tubing pressure with large, casing and tubing pressure differential, causing gas to go to this string.Use of small port size valve helps this problem but not eliminated totally.

    Inject in both strings simultaneously

    CHALLENGESGOALS

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 10

    Dual Gas Lift

    Using High Pressure Gas Lift for single point of injection

    Shear Orifice Valve failure

    Consider running a back up mandrel

    Challenge: Change valve using wireline tractor or coil tubing

    Pressure

    Dep

    th

    Gas LiftGradient

    Pt1

    Pt 2

    Zone 1

    Zone 2

    Pg OP

    FlowingGradientZone 2

    FlowingGradientZone 1

    Best suited if DP1 is very close to DP 2

    DP 2

    DP 1 Packer Depth

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 11

    UnloadingValves

    OperatingValves

    Gas Lift Design Practices (trial and error process)

    Production Pressure Operated Valves (PPO) as unloading valves and Injection Pressure Operated (IPO) as operating valve.

    IPO operating valve allows for higher gas injection rates compared to PPO valve

    Valve closure preserves casing pressure during shut downs.

    Mandrel Spacing PPO valve mandrel spacing design

    spacing for both strings accommodates either IPO or PPO valve spacing intervals

    Space both strings such that either can unload the packer fluid from the well.

    Unload strings in sequence, lower productive string first.

    Dual Gas Lift

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 12

    Questions?

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 13

    Backup

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 14

    Single Gas Lift Performance

    Zone 1

    Zone 2

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 15

    Dual Gas Lift Performance

    Zone 1

    Zone 2

    Zone 3

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 16

    Dual Gas Lift Performance

    Zone 1

    Zone 2

    Zone 3

    Zone 4

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 17

    Dual Gas Lift Performance

    Zone 1

    Zone 2

    Zone 3

    Zone 4

  • Feb. 4 - 8, 2007 2007 Gas-Lift Workshop 18

    Dual Gas Lift Performance