7120/1-1 R2
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General information
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Wellbore history
GeneralWell 7120/1-1 was drilled on the Alpha structure in the north of block 7120/1. The primary objective of the well was to test Palaeozoic carbonates and elastics in a partly fault-bounded/truncated dip closure on the western flank of the Loppa High. Potential Early Triassic sandstones in a low relief dip closure were a secondary objective.OperationsWell 7120/1-1 was spudded on 16 August with the semi-submersible installation "Borgny Dolphin" and drilled to 2569 m where it was suspended on 15 November due to NPD drilling regulations during winter season. On 2 December permission was granted to continue operations and drilling continued to 2610 m. On 26 December the well was again suspended at the request of the Norwegian Petroleum Directorate because of safety considerations in adverse weather conditions. The well was re-entered on 13 March 1986 and drilled to a TD of 4003 m in basement rocks. The well was drilled with seawater and bentonite hi-vis pills down to 485 m. From there to TD gypsum/polymer mud was used with various "Lost Circulation Material" pills to cure mud losses.The well encountered weak hydrocarbon shows from 800 m down to 2200 m and oil shows in Late Permian carbonates (Tempelfjorden Group, Ørret Formation). No intervals of significant reservoir potential were recognized from logs or described from cuttings in the Tertiary or Triassic sections. Below this sequence, three main Permian carbonate units were identified from logs and cuttings description. A porosity range of 5-10% for the limestone sequence between 2415 and 2461 m has been derived from log evaluation. In the basal part of this interval, a black shale was detected with a gas peak of 13% total gas. The lower limestone interval (2607-3277 m) contained weak fluorescence on cuttings from the top down to 2690 m.No coring was attempted in the upper section of this unit due to severe mud losses to the formation. A core was recovered from the base of the interval where alternating limestone, clay stone, marl and shale were described with porosities in the order of 4%. In the lowermost interval (3310-3951 m), dolomite was described as the main lithology with porosities around 3%. No shows were registered. In general, the carbonates had low porosities, but two zones of higher porosity were detected from logs between 2810-2850 m and 2610-2660 m. Two production tests indicated that the limestone was permeable, but no pore fluids were produced.Two cores were cut, one from 3186 m to 3194.5 m, a second from 4000 m – 4003 m in basement rocks. RFT fluid samples were taken at 2798 m ("Slight smell of hydrocarbons"), 3533 m, and 3714.5 m. Bottom hole temperatures from Wire line logging gave a maximum reading of 121 deg C at TD. True bottom hole temperature at TD is thus estimated to 125 °C. The well was plugged and abandoned as a dry hole with oil and gas shows on 21 July 1986.TestingTwo production tests were carried out in the Upper Permian intervals 2810-2855 and 2607-2665 m. Neither interval flowed any pore fluids, not even after acid treatment. Upon nitrogen displacement treatment some fluids were produced, indicating that the formations in both intervals contained water with traces of natural gas, while the interval 2607-2665 m also produced some oil film. Attempts to analyse the oil failed due to the small amounts. -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom13185.83194.5[m ]24000.04002.3[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]11.0Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit367490490692692110622852285231523732403240324302458260429972997322032203947 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.74 -
Geochemical information
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Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.02810285525.42.0260726656.4Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.02.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.02.0 -
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 typeCONDUCTOR30468.536480.00.00LOTSURF.COND.201101.0261112.01.37LOTINTERM.13 3/82093.017 1/22107.01.50LOTINTERM.9 5/82414.012 1/42426.00.00LOTINTERM.9 5/82414.012 1/42610.01.60LOTLINER74003.08 1/24003.01.80LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4061.3810.0WATER BASED5671.3910.0WATER BASED8091.4116.0WATER BASED20931.3920.0WATER BASED24141.3919.0WATER BASED24291.4041.0WATER BASED26071.25WATER BASED26121.4050.0WATER BASED26321.4012.0WATER BASED26521.4015.0WATER BASED26721.4015.0WATER BASED26941.3915.0WATER BASED26951.4015.0WATER BASED26981.4017.0WATER BASED27091.3912.0WATER BASED27301.3911.0WATER BASED27541.3911.0WATER BASED27701.3911.0WATER BASED27981.4010.0WATER BASED28041.4012.0WATER BASED28101.25WATER BASED28541.3910.0WATER BASED28551.3910.0WATER BASED28581.3911.0WATER BASED28611.398.0WATER BASED28851.3910.0WATER BASED28871.399.0WATER BASED29051.399.0WATER BASED29171.399.0WATER BASED29331.399.0WATER BASED29601.3910.0WATER BASED29741.3910.0WATER BASED30011.4012.0WATER BASED30371.3911.0WATER BASED30531.3911.0WATER BASED30931.3911.0WATER BASED31521.3811.0WATER BASED31571.3910.0WATER BASED31661.3910.0WATER BASED31851.3912.0WATER BASED32091.3910.0WATER BASED32251.3913.0WATER BASED32631.3911.0WATER BASED32861.3912.0WATER BASED33041.3912.0WATER BASED33401.3912.0WATER BASED33591.3914.0WATER BASED33861.4013.0WATER BASED34261.4012.0WATER BASED34371.3912.0WATER BASED35321.3913.0WATER BASED35511.3914.0WATER BASED35901.3914.0WATER BASED35981.2512.0WATER BASED36091.3913.0WATER BASED36591.3914.0WATER BASED37221.3914.0WATER BASED37251.389.0WATER BASED37581.257.0WATER BASED37881.258.0WATER BASED38091.258.0WATER BASED38261.258.0WATER BASED38441.258.0WATER BASED38571.259.0WATER BASED38741.2510.0WATER BASED38831.2512.0WATER BASED39071.2514.0WATER BASED39311.2512.0WATER BASED39391.2512.0WATER BASED39891.2512.0WATER BASED40001.1012.0WATER BASED40031.2511.0WATER BASED -
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]pdf0.28