31/3-2
Export: PDF
-
General information
-
Wellbore history
GeneralWell 31/3-2 was drilled immediately to the southeast of a fault that was interpreted as a boundary fault between Troll West and Troll East. The main objectives of the appraisal well 31/3-2 were to determine if hydrocarbons were present on the downthrown south side of the fault, to determine the contacts, and to determine the degree of communication across the fault plane. A test would be performed in the case of moveable hydrocarbons, in order to observe boundary effects where the pay zone is narrow and thin. The well was planned to reach total depth in the Early Jurassic Drake Formation at 2050 m if drilling through the "boundary fault". In the case of drilling entirely within the hanging-wall block the total depth was estimated to 2130 m.Operations and resultsWell 31/3-2 was spudded with the semi-submersible installation Treasure Seeker on 5 March 1984 and drilled to TD at 2090 m in claystones of the Early Jurassic Drake Formation. No significant technical problems occurred during drilling and testing. The well was drilled with pre-hydrated gel/seawater with sweeps of high viscous mud down to 629 m and with KCl/polymer mud from 629 m to TD.The Sognefjord Formation (1567 - 1706 m) was found oil bearing down to 1578.5 m where the oil/water contact was established. The oil-bearing reservoir consisted of very fine to very coarse-grained sandstones. They are friable to loose with only traces of siliceous or calcareous cement. The total net sand in the Sognefjord Formation was calculated to 132 m out of 139 m gross thickness, giving a net/gross ratio of 0.95 and an average porosity of 26.6%. A thin (0.5 m) gas cap could be present on top of the oil column. This was identified from LDT/CNL logs and was also consistent with the GOR development during the test, but was not confirmed by RFT data. There were no oil shows above the Sognefjord Formation, and no oil shows below1595 m, and the Middle to Early Jurassic sandstones was found water bearing.Evidence from seismic interpretations, dip meter analysis, and subsequent geometrical considerations indicated that well 31/3-2 penetrated the "boundary fault" at top Brent Group level, between 1940 and 1955 m. In this zone two calcite cemented bands were encountered thought to be associated with the fault plane. The OWC was found to be 3.5 m shallower than in well 31/2-6, but the pressure data from wells in the area did not have sufficient reproducibility and resolution to support different pressure regimes in the different compartments.Five cores were cut between 1565 m and 1640 m from the lower part of the Draupne Formation and into the Sognefjord Formation. RFT pressure recordings and sampling were performed in the reservoir interval and pressure tests were also made in sand intervals in the underlying formations with the deepest point in the Drake Formation (Dunlin Group). Segregated RFT fluid samples were recovered from 1567.6 m (two samplings, one with oil and one with gas and oil), 1576 m (mud filtrate and water), and 1577.8 m (mud filtrate with trace oil and gas),The well was permanently abandoned on 30 April 1984 as a gas and oil appraisal.TestingOne production test was performed over the interval 1567 - 1577 m in the oil zone at the top of the Sognefjord Formation. The test produced 1271.9 Sm3 /day of 27.5 deg. API oil together with 562588 Sm3/day of gas with gravity 0.620 (air = 1). The choke size was 63.5 mm. The GOR was 442 Sm3/Sm3 and the CO2 content was 1.0%. The pore pressure at the top of the reservoir was measured to be 158.15 bara (2293.8 psi). The temperature measured during the test was 69.5 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]460.002090.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom11565.01575.5[m ]21581.01590.7[m ]31593.01606.3[m ]41608.01626.0[m ]51626.01639.9[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]65.3Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
-
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory700.0[m]DCRRI720.0[m]DCRRI740.0[m]DCRRI760.0[m]DCRRI780.0[m]DCRRI800.0[m]DCRRI820.0[m]DCRRI880.0[m]DCRRI940.0[m]DCRRI960.0[m]DCRRI980.0[m]DCRRI1000.0[m]DCRRI1020.0[m]DCRRI1040.0[m]DCRRI1060.0[m]DCRRI1080.0[m]DCRRI1100.0[m]DCRRI1120.0[m]DCRRI1140.0[m]DCRRI1160.0[m]DCRRI1180.0[m]DCRRI1200.0[m]DCRRI1220.0[m]DCRRI1240.0[m]DCRRI1260.0[m]DCRRI1280.0[m]DCRRI1300.0[m]DCRRI1320.0[m]DCRRI1340.0[m]DCRRI1360.0[m]DCRRI1380.0[m]DCRRI1400.0[m]DCRRI1420.0[m]DCRRI1440.0[m]DCRRI1460.0[m]DCRRI1480.0[m]DCRRI1565.0[m]COD1566.0[m]COD1567.0[m]COD1569.0[m]DCOD1571.0[m]DCOD1575.0[m]COD1582.5[m]COD1583.5[m]COD1584.7[m]COD1588.0[m]COD1590.3[m]COD1593.0[m]COD1597.5[m]COD1600.8[m]COD1610.8[m]COD1610.9[m]COD1613.2[m]COD1613.6[m]COD1614.6[m]COD1614.7[m]COD1615.5[m]COD1616.0[m]COD1616.1[m]COD1617.0[m]COD1618.0[m]COD1618.2[m]COD1618.8[m]COD1620.1[m]COD1622.2[m]COD1624.5[m]COD1626.0[m]COD -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit365540540605112111211194128014521471153315331541154115671706172518511929193919391952196620062006 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.32 -
Geochemical information
-
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]pdf13.56pdf5.88pdf3.26pdf2.30pdf0.52pdf9.51pdf8.08pdf0.38pdf0.24pdf10.30pdf0.27pdf0.68pdf0.97pdf3.55pdf0.12pdf1.97pdf0.71pdf0.15pdf1.79pdf4.43pdf8.08pdf0.16pdf6.25pdf2.30pdf2.40pdf1.39pdf1.40pdf0.30pdf1.28pdf0.17pdf2.86pdf1.68pdf10.05pdf10.28pdf0.13pdf0.16pdf0.14pdf9.98pdf0.12pdf0.24pdf0.38pdf0.42pdf0.44pdf0.34pdf0.28pdf0.40pdf0.39pdf0.26pdf0.28pdf0.17pdf0.35pdf1.09pdf0.31pdf0.39pdf0.38pdf0.31pdf0.32pdf0.19pdf0.16pdf0.14pdf0.14tif0.14pdf0.03pdf0.04pdf0.82pdf1.06pdf3.81pdf3.34pdf0.09 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01567157763.5Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.060Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.012725630000.8900.620442 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL6101499CBL VDL13901705CBL VDL14001736CET GR13851702CST10401494CST15051979CST17502087DLL MSFL GR SP CAL15021639HDT6101492ISF LSS GR SP451622ISF LSS GR SP6101491ISF LSS GR SP15022085LDT CNL CAL GR451624LDT CNL CAL GR6101493LDT CNL CAL GR15021639LDT CNL CAL GR15022086RFT15671567RFT15671725RFT15671567RFT15761576RFT15771577RFT17252022SHDT15022087VSP-O10002075 -
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 typeCONDUCTOR30451.036451.00.00LOTSURF.COND.20609.026625.01.45LOTINTERM.13 3/81502.017 1/21515.01.56LOTINTERM.9 5/81805.012 1/42090.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4601.06WATER BASED5601.3711.0WATER BASED6501.2018.0WATER BASED12501.2519.0WATER BASED13551.3018.0WATER BASED16501.2240.0WATER 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]pdf0.19