34/10-23
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General information
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Wellbore history
GeneralWell 34/10-23 was drilled on the Gullfaks Gamma structure, south-southeast of the Gullfaks Sør Field in the Northern North Sea. The objectives were to prove a significant hydrocarbon accumulation, with the Brent Group as the primary target and the Early Jurassic as secondary target. The first well on the structure, well 34/10-20, had the same targets as 34/10-23, but was terminated in the Early Cretaceous due to technical problems.Operations and resultsWildcat well 34/10-23 was spudded with the semi-submersible installation Dyvi Delta on 6 May 1985 and drilled to TD at 4764 m into Sinemurian /possibly Rhaetian age sediments of the Statfjord Formation. The well took 28 days more than prognosed to drill. The main part of the extra time came in the 8 1/2" section, where among many other things, the BOP stack was pulled for inspection and repairs. A flow occurred at 4080 m just above top Brent Group, and approximately three days were used to bring the well under control. At 4409 m (4406.5 m TVD RKB) the deviation exceeded 5 deg. The last survey, at 4514 m (4510.8 m TVD RKB) m showed 9.1 deg deviation. If this deviation is extrapolated the vertical depth at TD is 4756.2, ca 8 m short of measured depth. The well was drilled with seawater and hi-vis pills down to 1252 m, with gypsum/lignosulphonate mud from 1252 to 3118 m, and with gypsum/lignosulphonate/lignite mud from 3118 m to 4525 m. At 4509 m the pipe stuck, and imco-spot/pipelax pills with 3% diesel were placed to free it. The final section from 4525 m to TD was drilled with a gel/lignosulphonate/lignite/Anco Resin mud system.The pore pressure increased through the entire Cretaceous section and reached a maximum of 1.96 g/cc at the top of the Brent Group. Gas bearing Brent sandstone was encountered at 4083 m, approximately 100 m deeper than prognosed. A gas-water contact established at 4120 m. Analyses of the gas and the DST liquids showed a condensate character with significant contents of heavier components up to C35, including biomarkers.Oil shows were recorded in sandstones in the Lista Formation from 2020 to 2050 m, and in the Kyrre Formation around 2954 m. Weak shows on limestone was recorded in the Svarte Formation from 3640 to 3714 m. Intermittent fluorescence was recorded on sandstones on cores, sidewall cores and cuttings below the hydrocarbon-bearing reservoir down to TD. Some of these could be due to pipe-freeing agents added at 4509 m.Eleven cores were cut from 4082 m to 4308 m in the Tarbert, Ness, Etive, and Rannoch formations with an average recovery close to 100%. RFT wire line fluid samples were taken at 4084 m, 4176 m, 4718.5 m, and 4718.6 m.The well was permanently abandoned on 13 October 1985 as a gas/condensate discovery.TestingOne drill stem test, DST1, was performed in the interval 4085 - 4095 m. The test produced 1720000 Sm3 gas, 150 Sm3 oil, and 15 m3 water per day through a 22.2 mm choke. The initial reservoir pressure was 785.3 bar and the draw-down was 41 bar. The GOR was 11500 Sm3/Sm3. The DST temperature was 150 deg C. -
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]230.004764.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom14082.04100.6[m ]24103.04130.5[m ]34130.54144.0[m ]44144.24167.0[m ]54167.54169.0[m ]64169.74197.0[m ]74197.64210.0[m ]84211.64224.0[m ]94225.14253.0[m ]104253.04279.4[m ]114280.04308.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]218.3Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory3887.5[m]DCGEOCHEM3897.5[m]DCGEOCHE3905.0[m]DCGEOCHE3917.5[m]DCGEOCHE3925.0[m]DCGEOCHE3932.5[m]DCGEOCHE3945.0[m]DCGEOCHE3957.5[m]DCGEOCHE3962.5[m]DCGEOCHE3967.5[m]DCGEOCHE3977.5[m]DCGEOCHE3985.0[m]DCGEOCHE4005.0[m]DCGEOCHE4015.0[m]DCGEOCHE4022.5[m]DCGEOCHE4035.0[m]DCGEOCHE4057.5[m]DCGEOCHE4082.5[m]DCGEOCHE4082.7[m]COD4083.0[m]CRRI4087.2[m]COD4090.0[m]DCGEOCHEM4092.8[m]COD4097.9[m]COD4098.0[m]CRRI4105.7[m]COD4107.5[m]COD4109.7[m]COD4114.8[m]COD4116.3[m]COD4120.7[m]COD4124.1[m]COD4126.7[m]COD4130.1[m]COD4134.6[m]COD4134.6[m]COD4139.5[m]COD4141.4[m]COD4143.0[m]CMOBIL4144.8[m]COD4147.2[m]COD4152.0[m]COD4153.7[m]COD4158.7[m]COD4161.7[m]COD4162.7[m]COD4166.6[m]COD4167.9[m]COD4167.9[m]COD4172.7[m]COD4174.7[m]COD4177.0[m]COD4180.8[m]COD4180.8[m]CRRI4181.3[m]COD4182.4[m]COD4183.6[m]CRRI4186.5[m]COD4187.6[m]CRRI4189.4[m]COD4191.2[m]CRRI4191.7[m]COD4192.9[m]COD4193.8[m]COD4196.2[m]COD4196.8[m]CRRI4198.2[m]COD4200.5[m]COD4201.8[m]COD4205.5[m]COD4207.5[m]COD4209.0[m]COD4209.5[m]COD4210.0[m]CRRI4212.1[m]COD4214.2[m]COD4214.3[m]CRRI4216.1[m]COD4217.9[m]COD4218.5[m]CRRI4221.6[m]CRRI4221.9[m]COD4223.2[m]COD4225.8[m]COD4226.3[m]CRRI4227.9[m]COD4228.0[m]CRRI4228.6[m]COD4230.0[m]CRRI4230.8[m]COD4233.7[m]COD4234.6[m]COD4234.7[m]CRRI4234.8[m]CRRI4235.8[m]COD4236.8[m]COD4237.3[m]COD4237.8[m]CRRI4241.0[m]COD4242.1[m]CRRI4242.1[m]COD4245.3[m]COD4248.7[m]COD4251.1[m]COD4255.1[m]COD4259.8[m]COD4263.7[m]COD4266.0[m]COD4266.0[m]COD4270.4[m]COD4272.0[m]COD4272.0[m]COD4272.3[m]CRRI4272.4[m]COD4275.4[m]COD4278.7[m]CRRI4278.7[m]COD4281.9[m]COD4284.6[m]CRRI4285.0[m]COD4287.6[m]COD4290.6[m]COD4293.6[m]COD4294.4[m]CRRI4296.5[m]COD4299.9[m]COD4302.2[m]COD4304.7[m]COD4305.6[m]CRRI4307.8[m]COD -
Oil samples at the Norwegian Offshore Directorate
Oil samples at the Norwegian Offshore Directorate Test typeBottle numberTop depth
MD [m]Bottom depth
MD [m]Fluid typeTest timeSamples availableDSTTEST14085.004095.00CONDENSATE28.09.1985 - 16:35YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit16490010511200165018901890195020112028207021092109246534503550356536903690376738623862392340844084409842434287433543354413451545784715 -
Geochemical information
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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]pdf3.06pdf41.13pdf38.88 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.04085409522.2Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.028.000Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.015017000000.8200.65011400 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL CCL9003100CBL VDL CCL22003830CBL VDL CCL33004538CST GR47204749DLL MSFL GR40504761ISF LSS MSFL GR2244764LDL CNL GR12394765RFT GR40844140RFT GR40844096RFT GR40844141RFT GR41764281RFT GR44354439RFT GR47154719RFT GR47164750SHDT GR38364485VSP2244764 -
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 typeCONDUCTOR30224.036225.00.00LOTCONDUCTOR30225.036227.00.00LOTSURF.COND.201239.0261252.01.69LOTINTERM.13 3/83100.017 1/23118.01.91LOTINTERM.13 3/83104.017 1/23115.01.91LOTINTERM.9 5/83834.012 1/43850.02.13LOTLINER74525.08 1/24525.02.20LOTOPEN HOLE4764.05 7/84764.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured11611.6529.03.9WATER BASED09.10.198520141.2020.03.9WATER BASED21.05.198520541.2517.03.9WATER BASED21.05.198520561.3322.04.9WATER BASED21.05.198522831.3424.05.4WATER BASED22.05.198523891.3822.06.9WATER BASED23.05.198527431.4555.09.0WATER BASED29.05.198529551.459.013.8WATER BASED29.05.198531151.4514.08.9WATER BASED05.06.198531201.3710.06.0WATER BASED10.06.198535031.7325.010.0WATER BASED17.06.198535031.6425.07.0WATER BASED14.06.198535031.7325.010.0WATER BASED17.06.198535491.7726.09.0WATER BASED17.06.198537891.8156.011.0WATER BASED25.06.198539241.8625.09.9WATER BASED16.07.198539631.9228.04.9WATER BASED16.07.198540071.9735.05.8WATER BASED16.07.198540802.0541.06.9WATER BASED17.07.198540802.0747.57.4WATER BASED18.07.198540802.0747.57.4WATER BASED18.07.198540822.0942.06.4WATER BASED19.07.198541002.0629.03.9WATER BASED29.07.198541002.0328.03.4WATER BASED29.07.198541002.0328.03.4WATER BASED29.07.198541202.0629.03.9WATER BASED25.09.198543082.0133.05.4WATER BASED07.08.198544382.0132.07.0WATER BASED16.09.198544902.0433.05.9WATER BASED15.08.198545252.0131.04.5WATER BASED19.08.198545691.9830.04.9WATER BASED02.09.198545761.9632.03.9WATER BASED02.09.1985 -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit4285.55[m ]4291.00[m ]4295.94[m ]4300.00[m ]4306.80[m ]4098.05[m ]4104.05[m ]4118.05[m ]4137.22[m ]4170.70[m ]4187.67[m ]4205.90[m ]4239.64[m ]4253.00[m ]4261.12[m ]4270.97[m ]4281.56[m ]4082.16[m ]4089.40[m ]4095.10[m ]4186.55[m ]4256.80[m ]4275.00[m ]4175.75[m ]4282.25[m ]4195.50[m ]4190.65[m ]4277.70[m ]4302.80[m ]4084.25[m ]4131.00[m ]4169.95[m ]4130.60[m ] -
Pressure plots
Pressure plots The pore pressure data is sourced from well logs if no other source is specified. In some wells where pore pressure logs do not exist, information from Drill stem tests and kicks have been used. The data has been reported to the NPD, and further processed and quality controlled by IHS Markit.Pressure plots Document nameDocument formatDocument size [MB]pdf0.21