Low Cost Field Development using Hybrid Risers Prahlad Enuganti Technical Manager 2H Offshore Engineering Ltd., Aberdeen 1
Typical Field Development Options Fixed Structure Shallow Water Platform Wells Floating Production Storage and Offloading (FPSO s) Flexible Catenary Risers (FCRs) Modified Steel Catenary Risers (SCRs) Free Standing Hybrid Risers (FSHRs) Other Floating Production Facilities (Semi-submersibles & Spars) FCRs SCRs Top Tensioned Risers (TTRs) Tension Legged Platform (TLP) TTRs SCRs 2
Proposed Alternatives Current drilling rig market is oversaturated Purchase at low cost compared to new build FPU Free Standing Hybrid risers are installed from the MODUs Option A MODU repurposed as FPU to be either minimal or full processing facility Fluid processed at MODU before export to shallow water facility Any future drilling, intervention can be done by a different MODU Option B MODU used for pre-drilling wells, FSHR installation Production fluids offloaded to FPSO MODU remains at field to drill future wells, install future risers, intervene on existing wells Solution for fields that would otherwise need a substantial production and drilling host (PDQ) Long lead-time and expensive TLP/FPU can be avoided Heavy construction vessel can be avoided 3
Buoyancy Tank Flexible Jumper(s) to Vessel Buoyancy Tank Connection Upper Riser Assembly Free Standing Hybrid Risers Key Components Steel Linepipe(s) Base Spool(s) Lower Riser Assembly Foundation
Free Standing Hybrid Riser Advantages Design decouples riser from vessel 1st order motions Not highly sensitive to environmental loading Good fatigue performance (F class weld offshore) Low vessel payload Pre-installable ahead of production host vessel Flow assurance flexibility Large insulation thicknesses Pipe-in-Pipe Can use corrosion resistant alloy lined pipe Installation flexibility pre or post laying of subsea flowlines and pipelines Lower the cost ($60MM to $25MM per installed riser) by installing from the MODU drilling on the field
FSHRs To Date Type Field Status Owner/Field Operator Yr. Installed Region (ft) Water Depth (m) Vessel Green Canyon 29/Garden Banks 388 De-commissioned Placid Oil Company/Ensearch 1988/1994 GoM 1,529/2,096 466/639 Semi-Submersible Bundle Girassol Operating Total Elf 2001 Angola 4,430 1,350 Rosa Operating Total Elf 2007 Angola 4,430 1,350 Spread Moored FPSO Spread Moored FPSO BP Greater Plutonio Operating BP 2007 Angola 4,300 1,311 Spread Moored FPSO Single Line Kizomba A & B Operating Exxon 2004/2005 Angola 3,330 to 4,200 1,006 to 1,280 Block 31 NE Operating BP 2012 Angola 6,890 2,100 Spread Moored FPSO Turret Moored FPSO P-52 Operating Petrobras 2007 Campos Basin 5,906 1,800 Semi-Submersible Macondo De-commissioned BP 2010 GoM 5,000 1,515 DP FPSO Cascade/Chinook Operating Petrobras 2010 GoM 8,531 2,600 Turret Moored FPSO Block 32 Construction phase Total TBC Angola 4675-6315 1425-1925 Turret Moored FPSO
Potential Applications Deep water field developments Remote locations Marginal fields But really, can be considered for most applications! 7
Worldwide Rig Count (Ref: IHS)
Option A MODU Repurposed as FPU Convert a drilling semi to a production host to reduce CAPEX Improve schedule to first oil Use FSHRs from subsea wells for production/injection and a FSHR for export
15 conversions were carried out in last major oil downturn between 1986-1999 Mostly semi-submersibles Water depths < 1000m Subsea developments using flexible risers Ref: Deegan, Loffman, Odufuwa, The conversion of Mobile Offshore Drilling Units to Floating Production System Issues, Opportunities and Challenges, DOT 2014 Option A Historical Precedent Northern Producer FPF Vessel Field Startup Region Water Depth (m) Argyll FPU Argyll Oil Field 1975 UK North Sea 150 Buchan A Buchan oil field 1981 UK North Sea 160 P-09 Corvina Oil Field 1983 Brazil 230 P-15 Pirauna 1983 Brazil 243 P-12 Linguado / Badejo Oil Field 1984 Brazil 100 P-21 Badejo / Salema Oil Fields 1984 Brazil 112 Argyll & Duncan Oil Deepsea Pioneer FPU Fields 1984 UK North Sea 150 P-22 Morela 1986 Brazil 114 P-07 Bicudo Oil Field 1988 Brazil 207 Veslefrikk B Veslefrikk Oil Field 1989 Norwegian Sea 175 AH001 Ivan Hoe Rob Roy Oil Field 1989 UK North Sea 140 P-20 Marlim 1992 Brazil 625 P-08 Marimba Oil Field 1993 Brazil 423 P-13 Bijupira / Salema Oil Field 1993 Brazil 625 P-14 Coral / Esrela / Caravela Oil Fields 1993 Brazil 195 Nan Hai Tiao Zhan Luihua 1995 South China Sea 300 P-25 Albacora II Oil Field 1996 Brazil 252 P-27 Voador 1996 Brazil 533 Tahara PY-3 1997 Indian Ocean 339 P-19 Marlim 1997 Brazil 770 Janice A Janice Oil Field 1999 UK North Sea 80 P-36 Roncador 2000 Brazil 1360 SS-11 Coral 2003 Brazil 145 P-40 Marlim Sul 2004 Brazil 1080 ATP Innovator Gomez Oil Field 2006 Gulf of Mexico 914 Originally Galley Oil Field now at Don Oil Field 2009 UK North Sea 350
A larger % of future developments will be in very deep and ultra deepwater (5,000ft +)
Riser Selection for DW and UDW Applications Flexibles > 5000ft WD have several challenges Needs heavy construction vessel for installation Large payload FPU Temperature limit of ~130 o C Limit on diameter Expensive Use of freestanding risers instead of flexibles Field proven compliant hybrid steel/flexible riser system suitable for high motion vessel Low riser payload to allow more for processing and/or drilling equipment
Option B - Permanent Moored Drilling Semi with FPSO Drilling semi would have the same functionality as a TLP: Permanent installation over field life (requiring permanent mooring system and offshore inspection) Drill grass root wells Workover / intervene on existing wells to maximum reservoir recoverability of the field life Install production risers to avoid use of a costly heavy lift installation vessel Subsea tree and riser configuration are designed to accommodate the following constraints: The motions of the drilling semi do not allow for dry trees risers so a system of subsea trees and a compliant production riser system is needed The use of a freestanding production riser and the transfer of production fluid to the FPSO minimizes additional payload and allows the drilling rig to be maintained
Deepwater W Africa and Asia solution Alternate to new build TLWP with drilling rig Produce through subsea trees located under drilling vessel to enable through life drilling/workover access to maximise recovery Offloads to leased FPSO providing overall low CAPEX solution Freestanding riser in deepwater for fluid transfer to FPSO
Liuhua Field Development Ref: Hall, Sheng, Krenek, Douglas, Macfarlane, Liuhua 11-1 Development Subsea Production System Overview, OTC 1996, Paper 8175 300m water depth South China Sea
FEED - 20 Slot TLP Preliminary Schedule Comparison Year 1 Year 2 Year 3 Year 4 Year 5 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q Integrated Rig With TLP Sanction & Detailed Design TLP Construction & Integration TLP Tendon Fabircation 1st Batch Riser Delivery (3 production and 1 drilling) Tendon Installation TLP Installation & Commissioning (Ready to drill or complete) First completion and first oil (1 well) X Producing (3 wells) X MODU Drilling (Batch set conductors and drill 4 wells) FEED Semi-submersible with FSHR Sanction & Detailed Design Puchase semi and conversion (w permanent moorings) 1st Batch 3 off Subsea Trees Delivery (w manifold, well jumpers and 1st Batch 1 off Riser Delivery (w surface and seabed jumpers) Mooring Pre Installation Semi Installation Drilling and completion from Semi (3 wells) FSHR Installation (1 off) Install flexibles and umbilicals (w flex lay vessel) First oil (with 3 wells) X
FEED - 20 Slot TLP Sanction & Detailed Design TLP Construction & Integration TLP Tendon Fabrication Preliminary CAPEX Comparison Integrated Rig With TLP 1st Batch Riser Delivery (3 production and 1 drilling) Tendon Installation TLP Installation & Commissioning (Ready to drill or complete) First completion and first oil (1 well) $90,000,000 $1,000,000,000 $90,000,000 $40,000,000 $25,000,000 $39,000,000 FEED Puchase semi and conversion (w permanent moorings) 1st Batch 3 off Subsea Trees Delivery (w manifold, well jumpers and umbilical) 1st Batch 1 off Riser Delivery (w surface and seabed jumpers) Mooring Pre Installation Semi Installation Semi-submersible with FSHR Sanction & Detailed Design Drilling and completion from Semi (3 wells) $35,000,000 $290,000,000 $35,500,000 $25,000,000 $5,250,000 $6,500,000 Producing (3 wells) MODU Drilling (Batch set conductors and drill 4 wells) Total Costing Assumptions West Africa Day rate Mob/Demob J-lay vessel $500,000 $3,500,000 Flex-lay MSV $250,000 $5,000,000 5th Gen MODU $250,000 $2,000,000 Crane Barge $175,000 $3,000,000 ROV survey vessel $150,000 $2,000,000 Anchor Handler $75,000 $500,000 Field Support Vessel $50,000 $500,000 $93,250,000 $1,377,250,000 FSHR Installation (1 off) Install flexibles and umbilicals (w flex lay vessel) First oil (with 3 wells) Total $12,500,000 $7,500,000 $417,250,000 Note: costs do not include day rate for drilling crew and consumables
Option B - Key Advantages over TLP/Spar Significant CAPEX saving - up to 50% vs. TLWP/Spar Faster schedule to first oil by one year or more Lower installation RISKEX compared with TLP and Spar installations Maintain life of field workover capability for maximum reservoir recoverability Conventional subsea recoverability lower than dry tree fields based on long term North Sea and Norway offshore experience Similar advantage provided by TLP, Spar or FDPSO vessels Manage reservoir uncertainty Maximum end of life well count is not a driver for drilling vessel selection Can initially be an early production system Subsea architecture is organically expandable using the drilling vessel and a MSV to install more trees, risers, flowlines and jumpers Vessel and riser system can be readily retrieved and relocated
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MODU Conversion Considerations Study of candidate vessel semi vs. drill ships W Africa swells, heave response, vessel heading older vs. newer generation vessels Establish production characteristics, riser payload range and export options Mooring design configuration and loads - global performance analysis Retrofit mooring structural design Structural and fatigue analysis for long term permanently moored service Weight control and damage stability Corrosion and fatigue survey and assessment Any remedial structural work at dry dock Long term offshore inspection and maintenance requirements Level and stage of processing required (if any) Chemical injection storage Deck space allocation for drilling and production equipment Riser hang-off structures Change in vessel designation under class rules
Summary Surplus rigs in the drilling market is an opportunity to reduce CAPEX by up to 50% and time to first oil by one year compared to an equivalent TLWP There have been many drilling rig conversions over the last 35 years, mostly to production platforms, except for Luihua which is a drilling and WO semi in 300m water depth moored over a cluster of subsea trees Subsea trees and freestanding risers enable a MODU to be repurposed as a permanent moored drilling and workover vessel for deepwater Arrangement provides expansion flexibility to minimize upfront CAPEX and protect against reservoir uncertainty Risers and vessels can be retrieved and relocated The drilling vessel and a light construction vessel can be used to install the freestanding risers to avoid the use of an expensive heavy lift installation vessel