15/12-19
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General information
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Wellbore history
GeneralThe Pi North well 15/12-19 was drilled on the northern lobe of the Maureen Terrace in the North Sea. The prospect is adjacent to the UK Armada complex of Fields (Fleming, Drake and Hawkins) and the Seymour Fields to the West and the Varg and Rev Fields to the North. The main objective of the well was to test the hydrocarbon potential in Sleipner/Skagerrak sandstone formations in the Pi North structure.Operations and resultsWell was spudded with the jack-up installation Mærsk Guardian on18 February 2008 and drilled to TD at 3212 m in Triassic rocks of the Skagerrak Formation. A 9 7/8" shallow gas pilot hole was drilled from TD in the 36" section at 203.5 m to 672 m. No shallow gas was seen. No significant problem was encountered in the operations. The well was drilled with sea water and pre-hydrated bentonite down to 672 m, with Aquadrill mud from 672 m to 1364 m, and with Carbo SEA oil based mud from 1364 m to TD.Top Jurassic was encountered at 2969 m and consisted of only 4 m Draupne Formation directly overlying the Triassic Skagerrak Formation. No sediments of the Jurassic Sleipner Formation were encountered. The Skagerrak Formation was hydrocarbon bearing. The sandstones had an average porosity of 17% net when using an 11.8% cut off in the oil case and 8.1% in the gas case. The reservoir system was complex with an upper reservoir with gas down to 2986.8 m (13.8 m TVD gross gas column, 9.21m net pay) and an underlying oil column of 35.7 m TVD gross (13.11m net pay). A lower reservoir with a 16.5 m TVD gross oil-leg (3.81 m net pay) was encountered at 3044.5 m. The two oil zones were separated by a 22 m thick zone of movable water (confirmed by RCI water samples). Pressure data in the different reservoir zones indicated different pressure regimes and varying pressure depletion caused by production from neighbouring fields. No oil shows were observed in the well other than in the Skagerrak reservoir sections.Three cores totalling 156.69 m were cut with 100% core recovery from 2975.0 to 3131.7 m in the Skagerrak Formation.RCI wire line fluid samples were taken at 2973.5 m (gas), 2983 m (gas), 2994.5 (oil), 3023.5 m (water/oil mix), 3056.2 m (oil), 3030.1 m (water), 3015 m (oil), and 3117.5 m (water).The well was permanently abandoned on 20 May as an oil and gas discovery.TestingThree drill stem test were conducted in the Skagerrak Formation.DST 1A tested the interval 3088 - 3102 m. It produced 318 Sm3 oil and 29450 Sm3 gas /day through a 28/64" choke in the main flow. The GOR was 93 Sm3/Sm3. The bottom hole temperature was 130.8 deg C.DST 1B tested the intervals 3088 - 3102 m and 3036.5 - 3064 m. It produced 657 Sm3 oil and 156620 Sm3 gas /day through a 44/64" choke in the main flow. The GOR was 239 Sm3/Sm3. The bottom hole temperature was 130.0 deg C.DST 1C tested the interval 3088 - 3102 m, 3036.5 - 3064 m, and 3023 - 3029 m. It produced 396 Sm3 oil and 831297 Sm3 gas /day through a 56/64" choke in the main flow. The GOR was 2102 Sm3/Sm3. The bottom hole temperature was 127.8 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]200.003212.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12975.03002.5[m ]23002.53066.9[m ]33067.13131.6[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]156.3Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Oil samples at the Norwegian Offshore Directorate
Oil samples at the Norwegian Offshore Directorate Test typeBottle numberTop depth
MD [m]Bottom depth
MD [m]Fluid typeTest timeSamples availableDST0.000.00OILYESDST0.000.00WATERYESDST1 C3058.002980.00OIL10.05.2008 - 02:26YES -
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 typeCONDUCTOR30194.036203.00.00LOTSURF.COND.20661.024672.01.56LOTINTERM.13 3/81360.017 1/21364.01.56LOTINTERM.9 5/82905.012 1/42911.01.56LOTOPEN HOLE3212.08 1/23212.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.03088310211.02.03036310217.53.03023310222.0Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.01312.01313.0127Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.0318294500.680932.06571566210.6802393.03968312970.6802102 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]MRCH TTRM GR EI29113210MRCH TTRM GR RCI29733190MRCH TTRM MREX29243208MRT TTRM GR VSP MLR4+ARS2753200MWD - DIR127206MWD - DIR206669MWD - DIR GR RES PWD206672MWD - DIR GR RES PWD D/N29063212MWD- DIR GR RES PWD13592911TTRM GR CN CDL28803212TTRM GR SW MT29733117TTRM SGR HDIL XMAC F11283212 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit128130324192419243325072622265326532663273728962896291129272969296929732973 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4471.069.0Spud Mud4710.005.0Spud Mud6061.085.0Spud Mud6721.2517.0KCl/Poly/Glycol8930.0013.0KCl/Poly/Glycol12820.0017.0KCl/Poly/Glycol13641.4217.0KCl/Poly/Glycol13640.0016.0KCl/Poly/Glycol14001.4737.0CarboSEA21600.0035.0CarboSEA27370.0031.0CarboSEA29111.4729.0CarboSEA29551.3829.0CarboSEA29750.0029.0CarboSEA30010.0029.0CarboSEA31311.3127.0CarboSEA31751.34Salt Base32120.00Salt Base32120.0032.0CarboSEA32121.3529.0CarboSEA