Low Cost Flexible Production System for Remote Ultra-Deepwater Gulf of Mexico (GOM) Field Development, Phase 2

Transcription

1 Low Cost Flexible Production System for Remote Ultra-Deepwater Gulf of Mexico (GOM) Field Development, Phase Jelena Vidic-Perunovic Doris, Inc. 1 Best of RPSEA 10 Years of Research - Ultra-Deepwater and Onshore Technology Conference August 30-31, 2016 The San Luis Resort, Spa & Conference Center, Galveston, TX rpsea.org

2 Project Background and Requirements RPSEA called for a study of alternative Floating Production System (FPS) concepts with potential for cost saving and more flexibility. A hypothetical Paleogene field in ultra-deepwater GoM is used in this study, with the assumed key design parameters. Initial topsides production rate of 60,000 bopd, with flexibility. Key Design Parameters 2

3 Project Phases o Phase I Finalized Production concept selection for early Paleogene UDW GoM ( Doris, Sevan Marine, WG, Rpsea, ABS) Concept Screening Concept Engineering (FPSO hull & mooring, riser, topsides, offloading) Concept Qualification Select Plant AREA or NODE & Section, Select CATEGORY, Discuss and agree INTENT GUIDE WORD The HAZID Process NO HAZARD IS IT POSSIBLE IS IT LIKELY? YES BRAINSTORM THREATS & CAUSES IDENTIFY ASSESS CONTROLS WHAT BARRIERS OR CONTROLS ARE REQUIRED TO PREVENT OR CONTROL THE EFFECT? Regulatory Review and HAZID Process by ABS o Phase II (Doris, Sevan Marine, OTRC, WG, Rpsea, NETL) Model Test Evaluation of the selected concept for application in the US GoM 3

4 Cylindrical Sevan FPSO Hull Main Characteristics CFPSO Hull Geometry Hull Main Particulars Hull Diameter Bilge box Diameter Bilge box plate Diameter Main Deck Diameter Process Deck Diameter Moonpool Diameter Main Deck El. (Hull depth) Process Deck El. Draft, Ballast / Loaded Freeboard to MD, Ballast/Loaded Freeboard to top of bulwark, Loaded 93 m 124 m 138 m 103 m 109 m 30 m 42 m 48 m 22 m / 31 m 20 m / 11 m 18.5 m Hull central moonpool with a diameter of 30m for hanging SCRs. Minimizes the coupling from roll/pitch motions at the riser hang-off location. Moonpool Arrangement 4

5 Motion Characteristics of Different Floaters Heave Motion RAOs 5

6 Phase 2 - Model Test at OTRC Texas A & M Offshore Technology Research Center, College Station, TX MODEL TEST OBJECTIVE: Global Performance in Operation condition Hurricane condition The model and test matrix extended for extra functionality to capture: Hull resonance Moonpool resonance Green water on deck Impact forces 6

7 Phase 2 Model Test Scope FPSO hull 1:64 instrumented to measure: 6DOF Motions 2 horizontal and 2 vertical accelerations Runup at 3 locations Relative elevation at 3 locations in moonpool Tension at the top 3 equivalent mooring lines Local impact force at 3 locations on hull Dynamic wind force applied by servo-winch Bubble Image Velocimetry (BIV) for green water 7

8 8 Phase 2 Model of Cylindrical Hull

9 Equivalent Mooring System Underwater View - Mooring System Static Offset Test:Force vs Surge, Loaded 9 Mooring line anchor plate

10 Moonpool Model Wave free surface elevation probes Underwater-Wave free surface elevation probes 10

11 11 Fragment from Test Matrix

12 OTRC Model Basin Test Set-Up L2102 Fatigue Sea State Hs=6m Tp=9s 12

13 Hull Response in 10yr Hurricane - Loaded L2103: Hs=10 m Tp=13 s Motion Max Min 13

14 Hull Response in 10yr Hurricane - Loaded L2107_10yr Hurricane condition Motion Max Min Hs=10 m Tp=13 s Vc=1.65 m/s Uwind=33 m/s 14

15 Hull Response in 100yr Hurricane - Loaded L2105_100yrWave Very good global performance in Hs=15.8m Tp=15.4s Low heave Pitch away from the large waves 15

16 Hull Response in 100yr Hurricane - Ballast B3104_100yrWave_Largest wave_ s_ec Captured wave height >30m, 2*Hs 16

17 Moonpool Wave Elevation 17 Wave elevation spectrum in L2101 Fatigue Sea State Hs=4m Tp= 8s

18 Motion Comparison Heave RAO Pitch RAO Surge RAO 18

19 Measured Hull Global Motions Pitch Response 100yr Hurricane waves only 100yr Hurricane waves and wind 100yr Hurricane waves/wind/current 19

20 Hull Global Motions Pitch Response L yr Hurricane combined L yr Hurricane waves only Calculated wave-frequency response in a good agreement with measurements 20 Quasy static pitch angle predicted by the tuned numerical calculation to the measurements, accounting for effects in addition to mooring coupling.

21 Measured Hull Global Motions Sway Response 100yr Hurricane waves only 100yr Hurricane waves and wind 100yr Hurricane waves/wind/current 21

22 Hull Global Motions Sway Response L2108 Sway motion underpredicted by simulation! 22

23 Hull Response in Current C2108 Current Spin-up Loaded recorded over 7200s Ref Current Sway Response Statistics max min mean range (m) rms (m) rms A/D surge sway Pitch Fluid energy deflects the floater in the form of the drag, resulting in the offset The vibration frequency increases with the flow speed 23 There may exist more than one mechanism for the dynamic responses, but vortex-shedding may be dominant one.

24 Green Water BIV Camera Too little freeboard for 1000yr condition: 24 Current induced pitch Low heave Unoptimized hull

25 Unfactored Fatigue Life (yr) Preliminary Riser Analysis Steel Pipe OD / 273mm Nominal Wall Thickness / 41mm Pipe Material API X65 Pipe Steel SMYS 65 ksi Corrosion Allowance 3mm Insulation Coating Thickness 3 Insulation Coating Density 50 lb/ft 3 Nominal Hang-off Angle 10.5 deg Hang-off Strakes 2500 m Touch Down Point (TDP) Fig. 4: Wall Thickness Sizing (10.75 OD & OD) Wall thickness according to NTL No G28 based on API RP Riser Model in Orcaflex (Assumed fully straked. Photo Mark Tool and Rubber OD WT=41 mm selected. X65 grade steel assumed. 3 mm corrosion allowance included. Steel Catenary Riser Fatigue Life Along Arc Length SEVANVessel, Random Sea, API X65 Standard Joint, Flex Joint at Riser Hang-off 100,000 10,000 1, Riser Arc Length (m) API X' Curve DNV E Curve DNV D Curve Realization No.4 worst case: 3h wave elevation > 2*Hs

26 Coupled Analysis (Hull, Mooring Lines, Riser) Model Test Prototype WD=371 m WD=2500 m Hybrid approach Scaled model => Full scale system 26

27 Coupled Analysis Based on: Measured motions Measured waves Measured mooring line tensions Full size model Refined full scale model (better segmentation of the SCR model from preliminary analysis) Equivalent model 27

28 Coupled Analysis Mooring Tensions Mooring Tension Comparison: Loaded Draft Cases ~<5% discrepancy Equivalent line vs Test Prototype vs Test-upwave lines: Tmin~32684 kn Tmax~63454 kn ML3 28

29 Coupled Analysis Full Scale Model 3h Time series Teff in TD L2108 Min Teff~400 kn in TD 29 SCR response improved as based on input model test physics Better refined model of the line Effect of the mooring lines

30 Summary Phase 1 - FPSO based on Sevan hull first order engineered to correspond to project requirements. Favorable motions and moonpool riser connection indicated a cost efficient riser type. The hull doesn t weathervane - inherently better motions than a ship in Hurricane condition. PHASE 2 :NEW CHALLENGES Extreme wave height High speed current UDW GoM environment *Hull behavior **Mooring system design Viscous effects VIM Green Water Reduce damping flat plate 30 Increase freeboard

31 Conclusions-Phase 2 o First order motion well predicted, Established tuned numerical model for further work o Concept hull/scr shows feasibility for UDW GoM based on the initial study criteria and measured motions and waves elevation o Generally good global motions in the wave tank o Quasi-static pitch in current induced more green water o Unpredicted sway offset 31 o Smaller flat plate to reduce static pitch, allow for more heave o Larger heave to increase freeboard o Increase freeboard and bulwark in loaded draft o Optimize mooring system

32 Future Work Need for more testing - Based on existing hull model Additional Testing: Wind Tunnel Test (screening study) Optimization of hull geometry and mooring system Wave tank tests of the modified hull VIM Testing CFD Analysis 32 Analysis of Optimized System Consolidation with Regulatory Requirements for System Robustness

33 Doris-Inc gratefully acknowledges support from o NETL, RPSEA o Sevan Marine o ABS Consulting o OTRC Texas A&M o PWG: Lihua Wang/Statoil Robert Seah, Ming-Yao Lee/Chevron Amal Phadke, Derrick Laskowski/ConocoPhillips Pierre Beynet Project Sponsor: Dale Marietta Doris-Inc dmarietta@doris-inc.com (832)

34 Contacts Principal Investigator: Jelena Vidic-Perunovic Doris, Inc Project Manager: Bill Fincham NETL Technical Coordinator: Bill Head RPSEA