25/2-11
Export: PDF
-
General information
-
Wellbore history
GeneralWell 25/2-11 was the second well to be drilled on the East Frigg Gamma structure in the Viking Graben. Seismic anomalies indicated shallow gas in the area. The well was primarily designed to test the reservoir productivity of the Frigg Formation. Secondly to test for possible gas accumulation in Late Oligocene sands which might represent a continuation of the gas-bearing sands encountered in the 25/2-10 well, which due to technical problems had to be abandoned without logging and testing. TD was prognosed to be 2075 m, the Frigg Formation at 1930 m and the Oligocene sands at 1005 m.Operations and resultsAppraisal well 25/2-11 was spudded 20 February 1987 by Golar-Nor offshore semi-submersible rig Nordtrym and drilled to TD at 2075 m in rocks of Eocene age. Due to the seismic anomalies that indicated shallow gas, the well was spudded 100 m north of the original location.Hard calcite cemented sands were encountered in Miocene where unconsolidated sands were prognosed. This caused 17 extra days of drilling, under-reaming and sidetracking. Top Oligocene was penetrated 20 m below prognosed depth, and top Frigg formation came 20 m below prognosis. Both targets proved to be hydrocarbon bearing. The main hydrocarbon-bearing reservoir encountered in Oligocene was a sand-lense at 1105.5 - 1111.5 m (1079.8 - 1085.8 MSL). Post-well gas chromatographic analyses of core chip extracts from Oligocene (1051 m and 1107 m) showed extensively biodegraded oil. The Frigg Formation oil/water contact was encountered at 1975 m, and gas/oil contact at 1960 m.Coring commenced from 1950 m to 1986 m with 50% recovery. Three runs to sample the oil from the Oligocene reservoir interval 1105.5 m to 1111.5 m were made by RFT through casing. No hydrocarbons were recovered. A RFT sample from 1967 m in the Frigg Formation recovered mud filtrate with traces of oil.The well was plugged and abandoned on 10 may 1987 as a gas and oil appraisal.TestingThe instability of shales on top of the Frigg formation excluded open hole testing, and a 7" liner had to be set and perforated for testing purposes. Three DSTs were attempted in the interval 1950 m to 1955 m. The two first did not produce but DST3 was successful, producing at maximum 666000 Sm3 gas /day with a 64/64 choke and WHP = 60 bar. -
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]240.002075.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom21951.01969.0[m ]31969.01969.9[m ]41973.01975.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]20.9Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
-
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit143476521102510461262135314501950 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.31 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf0.46 -
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]pdf4.87 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01958195325.4Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.015.0006.00018.00061Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.06660000.600 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]BGT229780CBL VDL501208CBL VDL8901930CST10471210CST12451565CST19502055DIL LSS GR229800DIL LSS GR7641226DIL LSS GR12141940DIL LSS GR19352074DLL MSFL GR9001200DLL MSFL GR19352071LDT CNL NGT7641226LDT CNL NGT19352073LDT GR12141940MWD1431958RFT00RFT19542040SHDT GR7641221 -
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 typeCONDUCTOR30229.036357.00.00LOTSURF.COND.20765.026808.01.38LOTINTERM.13 3/81214.017 1/21324.01.52LOTINTERM.9 5/81936.012 1/41962.01.58LOTLINER72075.08 1/22075.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured6211.0927.08.8WATER BASED27.02.19876581.0929.08.8WATER BASED02.03.19876781.1032.010.7WATER BASED02.03.19877461.1129.09.8WATER BASED02.03.19877821.0517.09.3WATER BASED18.03.19877851.1128.09.8WATER BASED05.03.19878001.1127.08.8WATER BASED05.03.19878081.0517.07.8WATER BASED19.03.19878401.0517.06.8WATER BASED23.03.19879171.0619.08.8WATER BASED23.03.19879731.0720.06.3WATER BASED23.03.198710551.0722.05.8WATER BASED24.03.198710731.0623.04.9WATER BASED25.03.198712301.0722.06.8WATER BASED26.03.198713241.0822.04.9WATER BASED03.04.198715081.1023.02.9WATER BASED06.04.198716321.1526.05.8WATER BASED06.04.198719001.1736.07.8WATER BASED06.04.198719471.1835.06.8WATER BASED07.04.1987 -
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]pdf0.19