15/12-12
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General information
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Wellbore history
GeneralThe objective for well 15/12-12 was to test the hydrocarbon potential of the Rev structure in PL 038 approximately 5 km south-east of the Varg Field (Varg A Platform). The target level was Oxfordian Intra Heather Sands of the Viking Group.Operations and resultsWell 15/12-12 was spudded with the semi-submersible installation Scarabeo 6 on 25 December 2000 and drilled to TD at 3085 m in the Triassic Skagerrak Formation. At ca 2700 m the well starts to build angle up to a deviation of ca 25 deg at ca 2830 m. This deviation is kept down to TD where it leads to a difference between measured and vertical depth of ca 30 m. The well was drilled with seawater and hi-vis pills through to the base of the 17 1/2" section at 1384 m and with Glydrill KCL Polymer from 1384 m to TD.A total of 121 m (2856 - 2977 m) gross Late Jurassic, Intra Heather reservoir sequence was penetrated in well 15/12-12 on the Rev Structure. The reservoir is interpreted as shallow marine sand bodies and is dated Oxfordian of age. On top of the reservoir lie 6 m sand dated Earliest Kimmeridgian of age. This sand was not considered as part of the net reservoir. The massive Intra Heather sands had very good reservoir quality. The cored interval of the reservoir had good hydrocarbon shows. Pressure data showed a clear gas gradient with a distinct GOC at 2954 m (2912 m TVD MSL) and an oil gradient down to base of reservoir (Top Triassic) at 2977 m (2932.5 m TVD MSL). MDT samples of the oil leg indicated an oil-down-to (ODT) situation. The pressure data also showed approximately 40 bars of depletion, caused by the production on the Varg Field (Southern Segment).The interval between 2864 - 3000 m was cored in six cores, nearly the complete reservoir section and the upper part of Triassic. MDT fluid samples were taken throughout the reservoir at 2867.5 m, 2895 m, 2961 m, 2964.2 m, and 2972.5 m. Samples from the two deepest levels recovered variable proportions of water and oil, reflecting the lack of a clear oil-water contact (OWC) in the reservoir. This is interpreted as an effect of the pressure depletion due to the production on Varg. Apart from the sampled water, which was heavily mud contaminated, sampled fluids were considered representative for the reservoir.The well was permanently abandoned on 9 February 2001 as an oil and gas discovery.TestingNo drill stem test was performed -
Cuttings at the Norwegian Offshore Directorate
Cuttings at the Norwegian Offshore Directorate Cuttings available for sampling?YESCuttings at the Norwegian Offshore Directorate Cutting sample, top depth [m]Cutting samples, bottom depth [m]1440.003085.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12864.02892.0[m ]22892.02920.0[m ]32920.02948.0[m ]42948.02974.7[m ]52976.02984.2[m ]62986.02997.7[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]130.6Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Casing and leak–off tests
Casing and leak–off tests Casing typeCasing diam.
[inch]Casing depth
[m]Hole diam.
[inch]Hole depth
[m]LOT/FIT mud eqv.
[g/cm3]Formation test typeCONDUCTOR30185.036185.00.00LOTSURF.COND.20599.026605.00.00LOTINTERM.13 3/81377.017 1/21384.02.18LOTINTERM.9 5/82829.012 1/42836.00.00LOTOPEN HOLE3085.08 1/23035.00.00LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]APS VSP CCL24603040CMR ECS28202983DP MDT29642972DSI ECS HNGS22002829FMI DSI CMR20021822362MDT28592937MDT28953040MWD ADN RAB28273084MWD CDR1131375MWD CDR CDN RAB13662823 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1131065124522382238225223122420244524452450255826512675271127112733277427932793286129772977 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.42 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf2.20 -
Documents – reported by the production licence (period for duty of secrecy expired)
Documents – reported by the production licence (period for duty of secrecy expired) Document nameDocument formatDocument size [MB].pdf6.86.pdf3.69 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1851.09WATER BASED4561.09WATER BASED9701.05WATER BASED21101.3520.0WATER BASED28361.3925.0WATER BASED28411.3523.0WATER BASED30851.3620.0WATER BASED30881.3619.0WATER BASED