31/2-16 S
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General information
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Wellbore history
GeneralWell 31/2-16 S was drilled as an appraisal in the Troll-West Oil province in the Northern North Sea. It was located on the crestal part of the Oil Province close to well 31/2-5. The primary objective was to drill hole and prepare for a long term production from a horizontal well drilled 5 m above the oil/water contact in the 23.5 m thick oil column. The length of the horizontal section should preferably be 500 m.Operations and resultsAppraisal well 31/2-16 S was spudded with the semi-submersible installation Deepsea Bergen on 27 September 1989 and drilled to TD at 2390 m ( 1587 m TVD RKB) in the Late Jurassic Sognefjord Formation. The well was drilled vertical down to 1118 m in the 17 1/2" section and kicked of from there, building angle up to a horizontal well path from ca 1950 m. Problems with tight hole, lost circulation and hard formation (stringers) were encountered repeatedly in the 17 1/2 and 12 1/4" sections from 1015 to 1891 m. The well was drilled with sea water and hi-vis pills down to 1015 m and with Versaport oil based mud from 1015 m to 1891 m, and with a super-saturated NaCl / polymer mud from 1891 m to TD. During well completion and preparation for production testing the screen-packer stuck at 570 m. Close to eight days were lost in milling and retrieving the fish before normal operations could be resumed.The Sognefjord Formation was encountered at 1659 m (1533 m TVD RKB). The established gas/oil contact in the Troll Field is at 1547 m MSL TVD, which is 1.5 m deeper than observed in this well. This 1.5 m is within the uncertainty of the TVD calculations, and a common gas/oil contact is assumed.No conventional or side wall cores were cut. No wire line pressure tests or fluid samples were taken. Apart from runs 1A, wire line logging was performed by the use of pipe conveyed Logging Systems. MWD was the only deep resistivity measuring device through the whole well.After drilling to TD the well was completed with 502 m 6 5/8" prepacked screens in the Sognefjord Formation reservoir, from 2390 to 1888 m (1587 - 1586 m RKB TVD). The well was completed on 27 December 1989 as an oil and gas appraisal. It was subsequently reclassified to test production well 31/2-T-16 S. After the test production it was again re-classified to development well 31/2-F-5 H.TestingA clean-up flow was conducted as part of the 31/2-16 S well completion. During this flow one bottom hole fluid sample and three separator PVT-sets (1 x oil/2 x gas) samples were taken. -
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]1030.001890.00 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit37778213581358141314531645165016591659 -
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]pdf17.08 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01888238450.8Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.04.00014.70067Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.01990894440.8820.638 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL CDL GR CCL3541604CBL VDL GR CCL - MISRUN14041885CDL CN GR15991795CDL CN GR - MISRUN15661900GYRO14651880GYRO14701880GYRO CCL3541590MLL CDL CN GR18852390MWD - GR CDR CDN DIR18881969MWD - GR CDR DIR10201905MWD - GR CDR DIR18882390MWD - GR RES SN DIR3541020PLS18502345 -
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 typeCONDUCTOR30439.036439.00.00LOTINTERM.201003.0261020.01.79LOTINTERM.13 3/81601.017 1/21607.01.45LOTINTERM.9 5/81888.012 1/41891.00.00LOTLINER72390.08 1/22390.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4391.05WATER BASED29.09.19896231.2511.06.0WATER BASED08.07.199110201.3454.015.0OIL BASED09.10.198910200.00WATER BASED03.10.198910200.00WATER BASED05.10.198910201.3452.015.0OIL BASED06.10.198910201.3451.015.0OIL BASED09.10.198910231.3653.014.0OIL BASED09.10.198913151.4147.011.0OIL BASED10.10.198913151.4144.011.0OIL BASED12.10.198913151.4146.011.0OIL BASED11.10.198913211.4042.010.0OIL BASED13.10.198913701.4146.011.0OIL BASED16.10.198913701.4150.011.0OIL BASED16.10.198913751.3936.09.0OIL BASED16.10.198913981.3935.08.0OIL BASED18.10.198914031.3531.08.0OIL BASED18.10.198915131.3544.013.0OIL BASED19.10.198916071.3548.014.0OIL BASED23.10.198916071.3537.09.0OIL BASED23.10.198916071.3548.014.0OIL BASED23.10.198916071.3537.09.0OIL BASED23.10.198916071.2526.04.0OIL BASED24.10.198916071.3538.09.0OIL BASED23.10.198916071.3538.09.0OIL BASED23.10.198916101.2631.07.0OIL BASED25.10.198916791.2533.06.0OIL BASED27.10.198917431.2639.08.0OIL BASED27.10.198917741.2736.09.0OIL BASED30.10.198918021.2633.08.0OIL BASED30.10.198918041.2631.07.0OIL BASED30.10.198918611.2512.09.0WATER BASED09.11.198918731.2633.07.0OIL BASED31.10.198918901.2314.011.0WATER BASED06.11.198918901.2413.011.0WATER BASED07.11.198918911.2731.07.0OIL BASED01.11.198918911.2734.07.0OIL BASED02.11.198918911.2734.07.0OIL BASED03.11.198918911.2734.07.0OIL BASED06.11.198918911.2314.011.0WATER BASED06.11.198919051.2413.013.0WATER BASED09.11.198919051.2513.012.0WATER BASED13.11.198919051.2513.012.0WATER BASED13.11.198919051.2513.011.0WATER BASED10.11.198919051.2513.013.0WATER BASED13.11.198920001.2513.013.0WATER BASED14.11.198920331.2614.012.0WATER BASED15.11.198920561.2514.012.0WATER BASED16.11.198921831.2513.012.0WATER BASED17.11.198923171.2615.013.0WATER BASED20.11.198923901.2514.016.0WATER BASED27.11.198923901.1511.06.0WATER BASED04.12.198923901.1511.06.0WATER BASED11.12.198923901.0511.06.0WATER BASED20.12.198923901.0511.06.0WATER BASED21.12.198923901.0511.06.0WATER BASED22.12.198923901.2512.08.0WATER BASED01.07.199123901.2512.08.0WATER BASED01.07.199123901.259.06.0WATER BASED01.07.199123901.2511.07.0WATER BASED05.07.199123901.269.05.0WATER BASED08.07.199123901.2615.014.0WATER BASED20.11.198923901.2510.06.0WATER BASED20.11.198923901.2512.07.0WATER BASED21.11.198923901.2512.07.0WATER BASED22.11.198923901.2516.018.0WATER BASED23.11.198923901.2516.018.0WATER BASED24.11.198923901.2515.016.0WATER BASED27.11.198923901.2514.016.0WATER BASED27.11.198923901.2510.08.0WATER BASED28.11.198923901.2513.012.0WATER BASED29.11.198923901.2511.07.0WATER BASED30.11.198923901.2511.06.0WATER BASED01.12.198923901.2511.06.0WATER BASED04.12.198923901.1511.06.0WATER BASED04.12.198923901.0511.06.0WATER BASED11.12.198923901.0511.06.0WATER BASED11.12.198923901.1511.06.0WATER BASED13.12.198923901.0511.06.0WATER BASED13.12.198923901.0511.06.0WATER BASED14.12.198929301.0511.06.0WATER BASED15.12.198929301.0511.06.0WATER BASED18.12.198929301.0511.06.0WATER BASED18.12.198929301.0511.06.0WATER BASED18.12.198929301.0511.06.0WATER BASED19.12.1989