25/1-10
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General information
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Wellbore history
GeneralWell 25/1-10 was drilled on the northern part of the Frigg Field in the Viking Graben. The primary objective was to test the Mesozoic "Deep Frigg" structure below the Frigg Field. The structure is a narrow north-south trending rotated mesozoic fault block. The first well drilled on the structure, 25/1-1, penetrated the top of Middle Jurassic sandstones at more than 4500 m, but was abandoned due to water flow associated with high pressure. The second well, 30/10-5, encountered both Middle Jurassic Brent Group sandstones and Lower Jurassic Statfjord Group sandstones, but the sandstones were water bearing. Well 25/1-10 was designed to test the remaining up dip potential of the Brent and Statfjord reservoirs. Secondary objectives were to establish the sweeping status of the Lower Eocene Frigg Formation and to obtain additional petrophysical data from this reservoir.Operations and resultsWildcat well 25/1-10 was spudded with the semi-submersible installation Vinni on 19 April 1988 and drilled to TD at 3739 m in the Middle Jurassic Brent Group. The interval 287-923 m was drilled with a 14 3/4" pilot hole to check for shallow gas. No gas was detected during drilling. The main problems during operations were encountered with the shales above the Frigg Formation and subsequent mud losses into the Frigg Formation. Further hole problems and mud losses occurred in the Brent Group, related to high pressures and fragile formation.Top of Frigg was found at 1926 m. The electrical wireline logs clearly showed that formation water has swept the gas that was initially present in the Frigg reservoir sands. Quantitative analysis indicate average porosities of 29 - 30 % and a residual gas saturation of 19 %. The well penetrated the Brent Group at 4771 m. Brent was found water bearing with an average porosity of 18 % and a Net/Gross ratio of 0.54. The average water saturation is 95 %. FMT pressure measurements showed a formation pressure of 926.8 bar at 4503 m. This is severe overpressure. For well safety reasons, the Statfjord formation was not drilled.Hydrocarbon indications were scarce except for generally high background gas readings from 3600 m within the Shetland Group and down to TD. Minor oil shows were recorded from 1955 m to 1980 m in the Frigg Formation and from 2863 m to 2870 m in the Shetland Group.One core was cut from 4473 m to 4483 m with 16% recovery. No wire line fluid samples were taken.The well was permanently abandoned on 14 September 1988 as a dry well.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]935.004740.00 -
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 typeCONDUCTOR30188.036188.00.00LOTSURF.COND.20910.026923.01.17LOTINTERM.13 3/82825.017 1/22839.01.72LOTINTERM.9 5/84043.012 1/44058.02.15LOTLINER74451.08 1/24471.02.25LOT -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL GR14502825CBL VDL GR27504451CDL CN GR19004745DIFL LSS GR1904575DIP GR32004058DIP GR44574720FMT HP36183700FMT HP45034685PDK 100 GR CCL19102010SWC GR44754590VSP9094745 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit12673019262171217122912423266240604259425943124471 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf0.56pdf0.72 -
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]pdf10.14pdf10.25 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured9851.0825.08.3WATER BASED03.05.198815881.1427.08.8WATER BASED05.05.198816351.1621.06.8WATER BASED06.05.198817801.17181.083.7WATER BASED09.05.198819391.2022.07.8WATER BASED09.05.198820621.2046.010.7WATER BASED18.05.198822331.2139.016.6WATER BASED24.05.198822331.2139.016.1WATER BASED25.05.198824191.2140.016.6WATER BASED26.05.198824851.2140.016.6WATER BASED27.05.198826221.2139.016.6WATER BASED30.05.198826711.2236.015.1WATER BASED31.05.198826931.2136.017.6WATER BASED02.06.198827261.2138.017.6WATER BASED02.06.198827411.2138.017.6WATER BASED03.06.198827871.2135.017.6WATER BASED06.06.198828331.2133.017.6WATER BASED06.06.198828391.2238.016.6WATER BASED06.06.198828441.2224.06.8WATER BASED13.06.198829411.2532.08.8WATER BASED13.06.198829511.2526.08.8WATER BASED13.06.198830371.2732.08.8WATER BASED14.06.198830511.2737.010.7WATER BASED15.06.198831401.2732.09.8WATER BASED16.06.198832301.2727.010.2WATER BASED17.06.198833401.2728.010.2WATER BASED20.06.198833841.2727.09.3WATER BASED20.06.198834741.3226.08.8WATER BASED20.06.198835551.3529.08.8WATER BASED21.06.198835691.4233.010.7WATER BASED22.06.198836351.4233.010.7WATER BASED23.06.198837061.5834.014.2WATER BASED28.06.198837771.6532.09.3WATER BASED28.06.198838461.6537.012.2WATER BASED28.06.198839531.6838.012.7WATER BASED28.06.198840581.7440.010.7WATER BASED01.07.198841591.8042.08.8WATER BASED19.07.198844702.0551.014.7WATER BASED27.07.198844972.1543.05.3WATER BASED22.08.198845742.1545.05.8WATER BASED22.08.198845932.1545.05.3WATER BASED23.08.198846272.1545.05.8WATER BASED24.08.198846762.1544.06.3WATER BASED25.08.198847082.1544.05.8WATER BASED26.08.198847392.1546.07.3WATER BASED29.08.1988