presentation
oabc
pet_eng_4097_lecture_2-15-project_overview.pdf
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PET ENG 4097 Senior design
Handout #2 Project data
Runar Nygaard
Overview of the area
www.google.com, www.npd.com
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Reservoir top map
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Seismic cross section
Field overview
• Southern North Sea oil discovery with well Exploratory wells Exp 1 and one appraisal well Exp 2. Additional data from Exp 3.
• The Fulmar SST formation is a ~20 meter thick sandstone.
• What is the NPV value to develop and produce the Fulmar SST (Ula formation) discovery?
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Exp 1 • Wildcat well Exp 1 was spudded with the semi-
submersible installation Deepsea Bergen in 1992 and drilled to TD at 3430 m in the Permian Zechstein Group. The well took 100 days to drill and test. The DSTs experienced severe difficulties with leakage and operation of down hole valves resulting in two mis-runs with testing string and a shortened DST no. 2.
• The greater part of the prospect, the Late Jurassic Ula sandstone (Fulmar) was encountered at 3327 m, and proved to be sandy. The Jurassic reservoir lithology consisted primarily of fine, well-sorted silica-cemented sandstone with poor visual porosity. Subsequent testing from 3348 - 3350 m showed a very tight formation, however testing from 3333 - 3342 m yielded oil. No oil- water contact was encountered, but organic geochemical analyses detected oil saturation in two intervals from the top of the reservoirs down to 3341, and from 3345 down to 3347 m.
Exp 1 Cores
• Four and a half m of shaley core was recovered in two cores from 3242 m to 3247 in the Mandal Formation. Good oil shows were observed in these cores. Organic geochemical analyses proved them to be excellent oil- prone source rock and with a maturity well within the oil window. Three cores were cut from 3338 m to 3363 m in the lower part of the Ula Formation and 17 m into the Triassic Smith Bank Formation. FMT pressures indicated a 0.766 g/cm3 oil gradient over the reservoir interval. Two FMT fluid samples were taken. Sample 4B at 3334 m recovered only mud filtrate. Sample 4C at 3335.4 m recovered 18.6 l mud filtrate and 200 ml of HC film.
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Exp 1 testing
• Two drill stem tests were performed in the well, DST 1 in Triassic sandstones and DST 2 in sandstones of Late Jurassic age. In DST 1 a two-metre interval from 3348 m to 3350 m was perforated. No reservoir fluid was produced to surface, but oil was trapped between two valves in the test string and the string content was also reversed out and directed to tank. Approximately 15 litres of oil were recovered from the test.
• The well was perforated from 3333 m to 3342 m in DST 2. It produced 784 Sm3/d of oil through a 24/64" (9.53 mm) choke, with a wellhead pressure of 15218 kPa and a temperature of 80 °C. The gas-oil ratio was measured to 20 Sm3/Sm3 with a separator pressure of 2032 - 2150 kPa and a separator temperature of 65 - 71 °C. Maximum down hole temperature was 144 deg C.
EXP 2 • Kelly bushing elevation [m] 43.0 • Water depth [m] 82.0 • Total depth (MD) [m RKB] 3459.0 • Final vertical depth (TVD) [m RKB] 3458.0 • The well was designed as a potential future water injector. • Operations and results • Appraisal well Exp 2 was spudded with the jack-up
installation to TD at 3459 m in the Late Permian Zechstein Group.
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Exp 2 Wellbore history
• Well Exp 2 was drilled in the North Sea. Two wells had previously been drilled for the evaluation of the Fulmar SSt structure. The Exp 1 was drilled in 1992 and discovered 19.5 m oil filled Fulmar Formation. No OWC was detected and no reliable pressure measurements were retrieved in the underlying Triassic Smith Bank Formation. The primary objective of the Exp 2 Fulmar SSt well was to appraise the Exp1 oil discovery. This objective included determination of the OWC deeper than 3372 m (3371.1 m TVD RKB) oil down to in well Exp1; to verify the seismic interpretation and geological model for the Fulmar SSt discovery, including facies changes in the Farsund Formation; and finally to obtain fluid samples (oil and formation water). The secondary objective was to test the reservoir potential of the Triassic Smith Bank Formation.
Exp 2
• The top of the Jurassic reservoir Fulmar Formation was encountered at 3382 m, 7 meter deeper than prognosed. The Fulmar Formation thickness of 18 m was penetrated. Pressure points taken from 3389 m to 3345.5 m (Fulmar Formation) varied from 632.73 bar to 633.69 bar. It gave an oil gradient of 0.076 bar/m equivalent to a density of 0.77 g/cc. The water density in the reservoir was derived from a sample (1.09 g/cc). From evaluation of the wire line logs, pressure points and sample analysis, the OWC was estimated to be found in the interval 3397 m to 3399 m MD RKB / 3396.1 m to 3398.1 m TVD RKB. Down to top Mandal Formation the gas composition was mainly C1 and there were no shows on cuttings. The entire Fulmar Formation sandstone and 4 m of the Skagerrak Formation had HC shows, from 3381 m to 3404 m. In the underlying Triassic sediments, no shows were seen.
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Exp 2.
• Two conventional cores were taken, from 3378.5 m to 3403.9 m and 3403.9 m to 3421.7 m with 97 % and 98 % recovery, respectively. RCI fluid samples were taken at three levels, 3392.5 m (oil), 3389 m (oil), and 3399.2 m (water).
• The well is permanently abandoned.
• Top Fulmar Fm Depthmap
– Owc (from Exp 1): 3353mTVD – Top Structure = 3289 m (top Fulmar
reservoir)
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7/7-3
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Map of top Fulmar
Exp 2
Exp 1
Exp 3
– The Fulmar formation can be correlated across the field as a sandpackage varying in thickness from 11 to 15meter. The sand has been divided into 5 zones in which the 1st and 3rd zone is non-reservoir due to high content of clay/transition zone and cement, respectively.
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Data on blackboard
• Well logs • Core reports with porosity and permeability measurements • Fluid analysis reports • Drill stem production test • End of well reports • Core photos
Surface facilities
• Two scenarios Production platform Subsea solution
www.statoil.com
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To Do’s for this week.
• Finalize your issue tree and project plan and get final approval.
Two scenarios
• Platform solution – Stand alone platform
with dry Christmas trees
– Wells to be drilled from the platform
• Subsea Production with tie-in to other structure – Stand alone platform
with dry Christmas trees
– Wells to be drilled from the platform
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Platform –
www.statoil.com
Cost for fixed platform solution
• Capital expenditure of building and installing platform $1,118,000,000
– 210,000 Daily operating cost – $57,000 Drilling cost per day
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Sub Sea with tie-back
www.statoil.com
Cost for fixed Sub-Sea solution
• Capital expenditure of building and installing Subsea production system $330,000,000
– 35,000 Daily operating cost – 78,000 OPEX of tie–in structure – + Drilling cost per day of jack-up
