Sedco 703 Enfield Intervention Campaign, 2008

Transcription

1 DrillSafe Forum Dec 2008 Sedco 703 Enfield Intervention Campaign, 2008 Andrew Clennett Drilling Engineering Team Leader 4 th December, 2008

2 Enfield North Aquifer Main Block North Enfield- 2 ENB02 ENB01 Main Block South END02 ENC01 ENC04 ENC02 Enfield- 1 ENC03 Enfield- 3 ENA05 Enfield- ENA044 ENB03 Oil Leg Sliver Block South Sliver Block North END01 Enfield- 5 Gas cap m Gas Oil Water

3 ENA-01ST1 Well Schematic ENA01ST1 Horizontal Producer Well Completion Schematic Drawn by: TM Date: Feb 2008 Reference: DOCS 4002, V15 Visio V1 Seabed / Delambre Mandu Korojon Gearle Muderong Lower Barrow Macedon Mudstone Macedon Sandstone 7" x 5-½" X/over 5-½" 17ppf 13Cr80 Tubing Air Gap = 26m Water Depth = 514m (LAT) 30" Conductor 7" 29ppf 13Cr80 Tubing 5-1/2" TRSV Control Lines TRSV = 1 GLM = 1 PDHG = 1 7" 29ppf 13Cr80 Tubing 13-3/8" 72ppf L80 Casing 5-½" Surface Controlled Hydraulic Gas Lift Mandrel 5-½" Dual Permanent Downhole Gauge Polished Bore Recep ptacle and Seal Assembly Top of Cement (above Packer) 9-5/8" x 5-½" Product ction Packer de Wireline Re-entry Guid 9-5/8" x 5-½" Sus uspension Packer 5 ½" Ported Pup Joint Upper Completion Design * Component m MDRT m TVDRT OD (in) ID (in) Tubing Hanger (OSST) TRSV Hydraulic Gas Lift Mandrel PDHG Carrier Production Packer Landing Nipple Wireline Re-entry Guide " 29 ppf 13Cr80 Tubing above GLM /2" 17 ppf 13Cr80 Tubing below GLM Suspension Design * Suspension Packer Landing Nipple (Upper) Landing Nipple (Lower) Tie-Back Seal Assembly Sandface Completion (8-1/2" Open Hole) * Gravel Pack Packer Flapper Valve OHGP / 5-1/2" 29 ppf Sand Screens /8" 24 ppf 13Cr80 Tubing (SC) above Sand Screens * Final component depths to be confirmed after well is drilled & cased ple 5 ½" x 4.437" Landing Nipp Tie-Back Seal Assembly 9-5/8" x 6" Gravel Pack Packer c/w PBR & Closing Sleeve 9-5/8" x 4.56" Formation Isolation Valve 7" 29ppf 13C Cr80 Tubing 7" x 5-½" X/over 9-5/8" 47ppf L80 Casing (13Cr Casing Windo ow) Well Cleanup Gravel Pack Mudsolv Displacement Deviation Limits: Gas Lift Mandrel Tailpipe Nipples Flapper Valve = 53 o = 66 o = 66 o OHGP c/w Horizontal AllPAC Shrouded Screen (5" 15 ppf / 18 ppf 13Cr80 base pipe, 10G (250 micron) screen, 16/30 Carbolite Gravel Horizontal Reach = xxxx Open Hole Section = yyyy Horizontal Reach / TVD =??? Not to Scale 8-½" Open Hole

4 Background Woodside has established intervention strategies on key assets to allow rapid remediation to return wells to production. Target to commence intervention time of 60 days. Enfield strategy highlighted key issues: ENA-01 & ENA-02 producer wells highest risk (Open Hole Gravel Pack) Remediation materials sourced Wells incorporated Open Water Trees (OXTs) required specialised rig interface equipment & rig capabilities Rigs identified: Nan Hai VI, Ocean Bounty, Jack Bates, Atwood Eagle Rigs discounted: Sedco 703 (crane, compensator, deck & fluids limitations) Previous campaigns experienced high currents and anchor slippage mooring critical even out of

5 Planning & Mobilisation Challenges ENA-01 cut sand December 28 th, well was closed in 3 rd January, 2008, Target intervention time of 60 days. Challenges during preparation: Rig Selection - Only rig available Sedco 703 Mooring: Mooring over infrastructure in cyclone season Sourcing of single synthetic pre-lay, and chain inserts Sourcing of Subsea buoy order, manufacture and delivery in 3 weeks Establishment of current monitoring/forecasting Tree Handling: Design & manufacture of OXT system interface frame for Sedco 703 Development of installation procedures NOPSA, DoIR, DEHWA & JVP approvals in place ENA-01 operations commenced March 1 st - 57 days after

6 Enfield Layout Sedco 703 Specific Anchor chain inserts added Singl e Prelay

7 Pre-laid Anchoring with Synthetic Inserts Subsea Buoy provides separation between synthetic & flowline 147mm polyester insert Flowline

8 Matrix Buoy

9 Currents

10 OXT/SLS Interface Structure

11 SLS and Interface Structure

12 SLS Interface Load Analysis SUMMARY A Normal Ops Rig Offset <3% B Accidental Mode Block Set-Down Rig Offset =<4% C Accidental Mode Tubing Stuck Rig Offset = 4% D Accidental Mode Tubing Stuck Rig Offset 6.62% E F G Accidental Mode Tubing Stuck Rig Offset 13.54% Load Test 1.5 x Normal Ops Loadings Tubing Parting Load Rig Offset 6.94% 8.41% (2) Vert. Force = 1539kN Shear Force = 58kN BM = 177.6kNm Vert. Force = 2059kN Shear Force = 58kN BM = 177.6kNm Vert. Force = 1539kN Shear Force = 58kN BM = 177.6kNm Vert. Force = 2974kN Shear Force = 128kN BM = 88.3kNm Vert. Force = 3217kN Shear Force = 307kN BM = 344.4kNm Vert. Force = 2309kN Shear Force = 87kN BM = 266.4kNm Vert. Force = 3217kN Shear Force = 307kN BM = 344.4kNm Vert. Force = dynamic stack loads + tubing tension (F t ). For cases E and F F t = 2500kN (tubing parting load). Load Case SLS Structure Spider Beams Intermediate Girder UC1 UC2 UC3 UC1 UC2 UC3 UC1 UC2 UC3 Case A Case B Loads < Case F. Refer Case F. Loads < Case F. Refer Case F. Loads < Case F. Refer Case F. Case C Refer Case A Refer Case A Refer Case A Case D Loads < Case E. Refer Case E. Loads < Case E. Refer Case E. Loads < Case E. Refer Case E. Case E Case F Case G Loads = Case E. Refer Case E. Loads = Case E. Refer Case E. Loads = Case E. Refer Case E. Notes 1) UC1 - fact/0.6fy (ratio between actual stresses to allowable stresses in accordance with AISC) UC2 - fact/fy (ratio between actual stresses to yield stress) UC3 - Mact/Mplastic (ratio between bending moment and plastic moment - plastic moment is maximum moment sustained by steel beam prior to collapse) 2) Limits vary depending on assumption of tubing size (7" vs 5") 3) Above loadings usubject to ICON internal verification

13 Working the operating envelope

14 Decision tree to commence OXT pulling operations Ready to commence Tree PullingOper ations Modified OXT pulling decision tree based on adjusted offset / sea state criteria. No Rig offset < 3% Yes Postpone operations (compensated) contact drilling superintendent (Ref to FMC Tree pulling operations) No Significant Wave Height forecast next 24 hours < 3.5m (period <20sec) No Yes Current forecast in next 24 hours < 1.22 m/s Yes Continue Operations

15 Operational Challenges ENA-01ST1 Well Abandonment: Cut tubing & pull OXT and tubing together required two trips Tree Retrieving Tool (TRT) would not latch and subsequently became stuck during retrieval operation several days to successfully pull tree ENA /8 casing cut & pull unsuccessful due to collapsed formation Utilised contingency 13-3/8 whipstock system successfully Drilling Risk of overpressures in 12-1/4 & 8-1/2 sections due to water injection Geotap readings in 8-1/2 hole showed ~500psi pressure differential along wellbore required additional mudweight and subsequent brine weight during completion Geosteered well horizontally in excess of the basis of design Completion Fluid Logistics, Fluid Logistics, Fluid Logistics (7000bbls required, 2000bbls available)

16 Source of Potential Overpressure ENA-03L1 ENA-01 ENB-01 ~2,100-2,200 psia L Barrow Group Sands ~4,000 psia 4,000-5,000 psia L Barrow Group S sand stringers Macedon Sand QRA assessed 1.3% ~3,200-3,300 chance of psia overpressure cause event at ENA-01 Mitigation barriers provided tolerable risk of consequence event(s) ~5,000 psia before shut-in expect 4,000-4,500 psia DRIMS #[number] Reservoir Author Pi = 3,057 Date [XX psia 2,060m 200X] TVDss #

17 Gravel Pack on the S703 Carrier Tubes Packing Tubes Washpipe Shroud Wirewrap Basepipe

18 Slickline fishing followed by CT fishing 21 days of fishing with 24 hour support and we got the well online!

19 And then ENA-02 cut sand.

20 Summary Learning Between Wells General Downtime events seen on ENA01 were eliminated. ENA02ST1 benchmarks as the tech limit well for Enfield Development. No field shut downs due to ENA02 rig operations. Learning Realised Hopped LRP/EDP from previous well leveraging tested/made-up equipment. Rig equipment downtime has been very minimal pump downtime eliminated. Understanding of rig constraints no wait on equipment. Planned casing sidetrack through milled window successful. One bottom hole assembly for 12-1/4 hole and also 8-1/2 hole. Clean-up of well prior to gravel packing extended and increased material availability. Gravel Pack rig up and contingency logistics

21 ENA01/02/03 Cumulative Comparison Enfield Intervention & Sidetrack Performance ENA-03L1 ENA-01ST1 ENA-02ST1 Well In Progress Subsea Prep Run EDP/LRP to OXT Kill Well Plug 2JNB Cut Completion above HHC Pull OXT / Upper Tubing Run BOP Abandon, Cut and Pull 9 5/8" Casing Kick Off Plug / Whipstock Drill 12 1/4" Hole Run 9 5/8" Casing Drill 8.1/2" Hole Clean Up Run Run Screens and OHGP Run 2JNB Pull BOP's Run OXT and Upper Tubing Suspension Days

22 Sedco 703 Enfield Intervention Campaign, 2008 Back-up slides 4 th December, 2008

23 Challenges Pre-lay excursion over FPSO exclusion zone