33/9-9
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General information
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Wellbore history
GeneralWell 33/9-9 was drilled in the northern part of the Statfjord field, about 1.6 km southeast of 33/9-3 well on the Tampen Spur in the northern North Sea. The objectives were to provide structural and stratigraphic control on the Brent reservoirs, and to provide stratigraphic control and to establish an oil/water contact for the Statfjord reservoir.Operations and resultsAppraisal well 33/9-9 was spudded with the semi-submersible installation Borgny Dolphin on 27 July 1977 and drilled to TD at 3100 m in Late Triassic sediments in the Statfjord Formation. The well was drilled with seawater down to 486 m and with a seawater/lignosulphonate mud system from 486 m to 1993 m. At 1993 m, TD in the 17 1/2" section, the hole was displaced to a freshwater/Lignosulphonate mud system. At the same point diesel was added to free the 13 3/8" casing which had become differentially stuck. After that the mud contained initially 5% diesel decreasing to traces of diesel at to 2489 m. From 2489 m to final TD the freshwater/Lignosulphonate mud system was without measurable diesel.No hydrocarbon shows were reported above the Brent Group. The Brent Group was found at 2413 m, 77.5 m deeper than prognosed 44.0 m thinner than anticipated in comparison to 33/9-3. Good oil shows were encountered at the top of the Brent Formation and continued throughout the reservoir down to top Dunlin Group at 2504 m. The entire Brent Group was oil-filled and it was above the field oil/water contact of 2609.1 m (2584.1 MSL). Log calculations showed that of the 87.0 m of gross oil section 84.6 m was net sand with 27.5% average porosity and 13.1% average water saturation. The Dunlin Group came in at 2504 m and log interpretation indicated a 23.2 m gross oil bearing reservoir between 2528.4 and 2551.6 m with 17.9 m net oil sand. The interval had 20.2% average porosity and 34.6% water saturation. Oil shows were reported from ditch samples and side wall cores in the Dunlin sand between 2535 and 2575 m. No OWC was established in the Dunlin Group. It was assumed that Brent and Dunlin had a common OWC at 2609.1 m (2584.1 MSL), outside well position. The Early Jurassic Statfjord Formation was penetrated at 2715.0, only 5.0 m deep to prognosis confirming that the Statfjord seismic reflector is a reliable mapping horizon. Good oil shows were reported from the top down to about 2850.0 m. The lowest potential pay sand indicated on the CPI log occurs between 2847.5 and 2852.5 m, but a test in this interval, DST No. 2, produced water with only trace oil. The anticipated oil/water contact was not found. The lowest-known-oil in the well at 2815.0 m (2790.0 m MSL) is 13.1 m above the lowest-known-oil previously established in the 33/12-2, which falls within a section of tight sands and shales in 33/9-9.A total of 23 cores were cut in the well. Cores no 1 to 8 were taken through the Brent reservoir and into the shaly top of Dunlin, while cores no 9 to 23 were cut in the Statfjord Formation. A significant error in core depth is noted for the first 16 cores. For these 11.3 m must be added to the registered core depths in order to match with the logger's depth. The last seven cores had core-log mismatch within +/- 2 m.The well was permanently abandoned on 17 November 1977 as n oil and gas appraisal well.TestingSix separate zones were successfully tested, requiring a total of nine attempts. The purpose of the tests was to obtain information from six separate zones in the Brent, Dunlin and Statfjord Sands in order to further evaluate the reservoirs. The tests for the first two zones were designed primarily for production data, bottom hole pressures and formation fluid samples, with sustained sand production expected only if very thin unconsolidated sand stringers were present. The last four zones where sand bonding was weak, as calculated from the well log data, had the additional test requirement of measuring the oil rate at which the formation sand broke down.DST 1 in the interval 2847.5 to 2852.5 m in the Statfjord Formation was a misrun.DST 2 in the interval 2847.5 to 2852.5 m in the Statfjord Formation produced 215 Sm3 water and only trace oil /day through a 3/4" choke. The recorded bottom hole temperature was 91.1 deg C. Sand was produced throughout the test, at rates from 1200 to 300 pounds/thousand barrels (ptb)DST 3 in the interval 2800.0 m to 2803.5 m in the Statfjord Formation produced in the final flow period 254 Sm3 oil /day through a 1/4" choke. The GOR was 82 Sm3/Sm3 and the oil gravity was 39.0 deg API. The recorded bottom hole temperature was 86.1 deg C. After the initial cleanup flow no sand was produced.DST 4 in the interval 2742.0 m to 2745.0 m in the Statfjord Formation was a misrun.DST 5 in the interval 2742.0 m to 2745.0 m in the Statfjord Formation produced in the final flow period 513 Sm3 oil /day through a 5/16" choke. The GOR was 93 Sm3/Sm3 and the oil gravity was 38.7 deg API. The recorded bottom hole temperature was 89.4 deg C. Sand was produced after each rate change (20 ptb), but cleaned up rapidly. Sand began producing more or less continuously, in bursts, on 5/8" choke (40 ptb) indicating formation was breaking down.DST 6 in the interval 2742.0 m to 2745.0 m in the Statfjord Formation produced in the final flow period 299 Sm3 oil /day through a 1/4" choke. The GOR was 129 Sm3/Sm3 and the oil gravity was 38.6 deg API. The recorded bottom hole temperature was 89 deg C.No sand was observed other than a few grains upon initial cleanup on 7/16" choke.DST 7 in the interval 2531.0 m to 2537.0 m in the Dunlin Group produced in the final flow period 442 Sm3 oil /day through a 23/64" choke. The GOR was 117 Sm3/Sm3 and the oil gravity was 34.4 deg API. The recorded bottom hole temperature was 82.8 deg C. On 1 1/4" choke sand production was observed on a continuous basis at about 120 ptb.DST 8 in the interval 2458.0 m to 2460.7 m in the Brent Group produced in the final flow period 525 Sm3 oil /day through a 24/64" choke. The GOR was 144 Sm3/Sm3 and the oil gravity was 37.6 deg API (measured in the first flow period). The recorded bottom hole temperature was 80.1 deg C. Only small amounts of sand were produced.DST 9 in the interval 2426.0 m to 2432.8 m in the Brent Group produced in the final flow period 416 Sm3 oil /day through a 22/64" choke. The GOR was 170 Sm3/Sm3 and the oil gravity was 38.5 deg API (measured in the first flow period). No temperature was recorded due to malfunction in the temperature gauge. Small amounts of sand were produced throughout the test. No measurable sand was produced on the highest flow rate (50/64" adjustable choke). -
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]254.003101.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12414.02421.9[m ]22432.32444.3[m ]32444.32444.8[m ]42446.32455.3[m ]52455.32468.3[m ]62468.32482.3[m ]72482.32500.6[m ]82500.62517.8[m ]92719.02722.3[m ]102722.32732.3[m ]112732.32740.3[m ]122740.32754.8[m ]132754.82768.6[m ]142768.82774.3[m ]152774.32786.6[m ]162786.62793.0[m ]172793.02807.5[m ]182807.52818.4[m ]192818.42826.2[m ]202826.22837.5[m ]212837.52853.5[m ]222853.52866.0[m ]232866.02876.5[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]249.2Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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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 typeCONDUCTOR30244.036249.00.00LOTSURF.COND.20475.026486.00.00LOTINTERM.13 3/81984.017 1/21993.00.00LOTINTERM.9 5/83068.012 1/43100.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]2.02848285319.03.02800280419.05.02742274515.96.02742274511.07.02531253830.08.02458246119.09.0242624330.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]2.03.030.0005.034.0006.038.000897.024.0008.034.0009.0Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]2.03.014380.8304125.012060.8305456.08630.8306187.013270.8305698.014680.83010599.0 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]DLL23503100FDC CNL4753100GR SPECTRO23503100HDT23003100ISF SONIC2453100LS SONIC19903098RFT00VSP3552955 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit17099716601660169318482396241325042504252825582715 -
Geochemical information
Geochemical information Document nameDocument formatDocument size [MB]pdf1.24 -
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]pdf2.47pdf0.98pdf2.33pdf1.80pdf2.95pdf0.82pdf10.65pdf6.73pdf1.31pdf2.95pdf0.59pdf0.53pdf0.87pdf10.47pdf12.44pdf3.03pdf6.89pdf1.64pdf0.13pdf3.67 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2491.07waterbased7601.14waterbased11371.16waterbased15681.25waterbased19931.37waterbased24211.72waterbased -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory2420.3[m]CLAP2420.3[m]COD2431.1[m]COD2431.1[m]CLAP2433.8[m]CLAP2433.8[m]COD2434.4[m]COD2434.4[m]CLAP2436.1[m]CLAP2436.1[m]COD2436.5[m]COD2436.5[m]CLAP2437.2[m]CLAP2437.2[m]COD2437.8[m]COD2437.8[m]CLAP2438.6[m]CLAP2438.6[m]COD2438.7[m]COD2438.7[m]CLAP2440.9[m]CLAP2440.9[m]COD2442.8[m]COD2442.8[m]CLAP2443.0[m]CLAP2443.0[m]COD2443.0[m]COD2443.0[m]CLAP2443.5[m]CLAP2443.5[m]COD2444.5[m]COD2444.5[m]CLAP2446.3[m]CLAP2446.3[m]COD2446.9[m]CLAP2448.6[m]CLAP2448.6[m]COD2448.8[m]COD2448.8[m]CLAP2448.9[m]CLAP2448.9[m]COD2450.3[m]COD2450.3[m]CLAP2451.8[m]CLAP2451.8[m]COD2453.3[m]COD2453.3[m]CLAP2455.0[m]CLAP2455.0[m]COD2455.3[m]COD2455.3[m]CLAP2456.6[m]CLAP2456.6[m]COD2459.3[m]COD2459.3[m]CLAP2469.3[m]CLAP2469.3[m]COD2486.0[m]CLAP2489.0[m]CLAP2494.0[m]CLAP2497.0[m]CLAP2500.0[m]CLAP2502.0[m]CLAP2503.0[m]CLAP2504.0[m]CLAP2507.0[m]CLAP2512.0[m]CLAP2516.0[m]CLAP -
Thin sections at the Norwegian Offshore Directorate
Thin sections at the Norwegian Offshore Directorate DepthUnit2748.45[m ]2751.45[m ]2756.30[m ]2759.20[m ]2764.55[m ]2765.88[m ]2782.55[m ]2799.60[m ]2809.30[m ]2722.85[m ]