Kizomba TLP Gas Lift Completion Design · Completion Design Kizomba TLP Gas Lift February 2006. Exxon Mobil Corporation has numerous subsidiaries, many with names that include ExxonMobil,

Kizomba TLP Gas LiftCompletion DesignKizomba TLP Gas Lift Completion Design

February 2006

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.

Corporate Separateness

Kizomba TLP Gas LiftCompletion DesignKizomba TLP Gas Lift Completion Design

January 2006

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Esso Exploration Angola (Block 15) Limited

Typical TLP Producing Well

Typical TLP Producing Well

Kizomba A & B TLP wells design• 5-1/2” production tubing • 2-3/8” methanol/gas lift tubing “side string”

Surface trees are 5-1/2 x 2-3/8” dual trees with access to the side-string through the tree’s 2” bore.

Intent of gas lift is to provide a means of kick-off and to boost liquid production rates.

Size of the line is determined by anticipated gas injection rate and by simultaneous MeOH injection rate of 1300-BPD for a “cold start”condition.

Dual Tree

~14m Long Section of 2" OD Coiled Tubing on Inj Side

'X' Nipple @ 129mTubing, 2.375", 4.7 ppf, L-80, Hydril 533 (Inj. Side)

CIS, DHPT, SCSSV, KHI & Riser Displacement EachHave Dedicated Control Lines

'X' Nipple w/ 'MCX' Inj. Valve Installed&

Nova KHI Sub

Y-Block w/ 'XN' Nipple in Injection SideRL-1S Baker TR-SCSSV, TM-5 w/ 4.562" 'LP' Hydraulic

Nipple & w/ Flow Couplings Top & Bottom

Halliburton 4.563" 'FBN' (Max 50° Dev.)w/ Flow Couplings Top & Bottom

Tubing, 5.5", 17 ppf, 13Cr-85, Vam TOP HC (Prod Side)

Nova Pressure & Temperature Gauge Nova Chemical Injection Sub Halliburton 4.563" 'FBN'

/

43.5m

RLPCL-80Production Riser 10.750" 51.0 ppf

10.750" 55.5 ppf

X-5620" 129 ppfSurface Casing

TLP Slot / Drill Center

Mudline @ 1201m MDVetco RL-4X-5630"

Intermediate Casing

Production Casing

Wire Wrap GP Screen,

PBR Top (MD RKB)

FSO Ball Valve (MD RKB)"VGP" Gravel Pack Packer Top (MD RKB)PBR Bottom (MD RKB)

Tell Tale Bottom (MD RKB)Isolation Plug Depth (MD RKB)

Double Valve Float Shoe (MD RKB)

Blank Pipe Top (MD RKB)

Screen Bottom (MD RKB)

Blank Pipe w/ Shunts Top (MD RKB)Screen Top (MD RKB)

TD (MD RKB) TD (TVD RKB)

Vam TOP

N-80 Vam TOP68 ppf13.375"

457 ppfStructural Casing

9.625" 47 ppf

"VGP" Gravel Pack Packer ID 6.000"

N-80

N-80 Vam TOPXO

Maximum Hole InclinationOriginal Rig Elevation (MWL - RKB) 24.0m

All Depths in m RKB

Pipe Drift 9.625"

Current Rig Elevation (MWL - RKB) Water Depth 1177m

Mudline Temperature

Production Casing

FSO

SealAssy.

FBN

DHPT

CIS

FBN

KHI

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Surface Dry-TreeSurface Dry-Tree

Gas lift –Injection Wing

ProductionWing

5-1/2” Production Tubing

2-3/8” Gas-Lift Tubing

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Wye-BlockWye-Block

5-1/2” ProductionTubing

2-3/8” Side stringTubing

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Gas-Lift ValveGas-Lift ValveConsidered conventional side-pocket mandrel style valve with a flow-through latch design.

Requirement to inject MeOH at higher rates prompted a search for a design that did not place the latch mechanism in the direct flow path.

Flapper type injection valve (shown left) when installed below either an ‘X’ or ‘XN’ Lock Mandrel provided alternative. This type valve provides a fixed replaceable orifice to control gas flow.

Differential pressure acting across the orifice with flow pushes the flow tube downward to open the flapper, holding the sealing mechanism out of the flow stream much as a subsurface safety valve. When flow stops, a power spring pushes the Flow Tube upward allowing the Flapper to close.

The drawing at left shows the valve in the closed position (not injecting fluid) on the right and in the open (fluid injection) position on the left.

‘X’ or ‘XN’ Lock Mandrel installs on top

Orifice

Flow Tube(down)

Flow Tube(up)

Flapper(open)

Flapper(closed)

Power Spring

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Potential for ErosionPotential for Erosion

Potential for slug flow, and erosional velocities, when mixing MeOH w/ gas lift for cold start up in the vertical side string.

Conducted two-phase flow analysis of injected gas and MeOH in the vertical 2-3/8” string.

Results of the study at right show that slug flow would not occur under anticipated operating conditions or at flow velocities surrounding those conditions.

Anticipated operating envelope

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Installation - OrientationInstallation - OrientationGuide Pin and alignment slot used between the Hanger and Head to properly orient the Dual Tubing Hanger to the Dual Tree bores

To provide this alignment without rotating the completion string (consisting of dual tubing strings along with 5-control lines), orientation couplings were used on the production tubing.

Side string orientation with respect to the Hanger could not be controlled – needed to wrap the string while controlling the helix angle

Tested both 2” coil-tubing and threaded & coupled 2-3/8”tubing around 5-1/2” tubing. Intent was to be able to wrap the tubing by hand, then gain slickline access. The photo at right shows 2” coil-tubing wrapped 180-degrees over about 40-feet.

Coil-Tubing was investigated as a means to accommodate space-out of both Production Tubing and Side-String at the Hanger. Coil-Tubing could simply be cut to length and a suitable connector installed; contingency plan was to use 2-3/8” threaded and coupled tubing.

We found that both 2” coil and 2-3/8” tubing could be wrapped. We also discovered that wrapping by hand could be done to generate a helix angle too tight to permit slickline access. The lesson learnt is to wrap the side string over the maximum available length

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Installation – CT ConnectorInstallation – CT ConnectorUse of Coil-Tubing in a production string requires stringent qualification of the end connectors.

Connector design featured two O-Rings as a seal and a standard threaded pin connection.

– Replaced O-Rings with a premium seal stack– Replaced the standard pin thread with a premium thread

qualified for use in the remainder of the T&C side-string.

Qualified modified connector design, at our Tubular Goods Test Facility (TGTF) according to the same test schedule used to qualify all premium threaded connections while using gas as the test medium.

In order to assure consistent quality of the coil-tubing, 50-foot lengths were shipped from the mill prior to ever being coiled. The intent is to provide tubing that is both straight and round where the connector is installed.

At installation, the coil-tubing is wrapped around the production tubing, then cut to length. A connector is installed and then landed in the Tubing Hanger.

2” Coil-Tubing

2-3/8” Hydril Thread

Premium Seal Stack

Slip &Cone

Shoulder

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Installation – SITInstallation – SITThe first Kizomba A upper completions were run in batch mode, completing 10-wells that were pre-drilled 12 to 18-months prior to arrival of the TLP. To assure this somewhat complex completion would fit inside the production riser and that we could efficiently and effectively orient and terminate tubing and control lines, Esso performed a SIT (System Integration Test) of the top three-joints of production tubing. Control lines were terminated below the Hanger and again outside the Tubing Head.

The SIT confirmed fit of proposed completion equipment as well as providing valuable opportunities to evaluate completion technique for improved efficiency. Completion personnel scheduled to participate in batch completions were allowed to practice the operation. The concept was, test one and complete ten.

Slip &Cone

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InstallationInstallationRunning the dual tubing string with 5-control lines in an efficient manner while protecting integrity of the completion was a challenge. The contract casing handling company was asked to purpose-build a spider specifically for the Kizomba completions.

2-3/8” T&C Tubing

5-Control Lines(color coded)


Purpose-built spider for Kizomba Completions


Slot/Hook for 2-3/8” Tubing

Cavity to protect 5-Control lines when

closing Slips

Control LinePusher Arm

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InstallationInstallationInside the single barrier 10-3/4” Production Riser Esso Ran the dual tubing string with 5-Control lines. To control bending load transfer between the riser and production tubing Esso used special clearance cross-coupling clamps at each coupling as well as molded mid-joint centralizers according to a centralizer schedule of one to three centralizers per tubing joint.

2-3/8” T&C Tubing



“Special Clearance”Cross-Coupling

protector


Production Riser Centralizer

2-3/8” T&C Tubing


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InstallationInstallation

Tubing strings were spaced-out and control

lines terminated under the Tubing Hanger.

2-3/8” Tubing Hanger Neck Pre-Bent Control

Lines

5-1/2” Production Tubing Side with 2-Way Check Installed

Highest efficiency was achieved by terminating all control lines larger than 1/4”

below the Tubing Hanger. Pre-bent lines were used for the 3/8” and 1/2” lines

installed above the Hanger inside the Tubing Head as shown in the photo at right.

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ConclusionsConclusionsOver the past four years Esso completed more than 30-producing wells in Block 15, most using the gas-lift style completion shown. All of these wells used the gas-lift side-string for kick-off, chemical injection, or in some cases gas lift to increase production rate. All completions have been successful in achieving performance objectives and surpassing production targets, all ahead of schedule.

ThanksThanksThanks to Patrick Hyde – completions

design engineer and primary author.

Documents

Kizomba TLP Gas Lift Completion Design · Completion Design Kizomba TLP Gas Lift February 2006. Exxon Mobil Corporation has numerous subsidiaries, many with names that include ExxonMobil,