2/1-9
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General information
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Wellbore history
GeneralWell 2/1-9 was drilled on the Gyda South structure, a fault/dip closure in the Late Jurassic fairway on the eastern flank of the Central Graben, 6 km south of the Gyda Field. The main objective of the well was to test the Late Jurassic "Gyda sandstone" (Ula Formation) target and prove a volume of oil that was commercial as a tie back development to the Gyda platform. Secondary reservoir potential existed in both the Middle Jurassic and in the uppermost part of the Triassic. Estimated TD was 4275 m TVD RKB.Operations and resultsAppraisal well 2/1-9 was spudded with the semi submersible rig Ross Isle 15 March 1991 and drilled to TD at 4298 m in the late Permian Zechstein Group. No significant problems were encountered in the operations. No shallow gas was detected. The well was drilled with seawater and high viscosity slugs down to 900 m, and with Aquamul ether-based invert emulsion mud system from 900 m to TD.A 59 m Forties Formation sandstone sequence was encountered at 2923 m in the Late Paleocene and another ca 30 m thick sandstone sequence at 3025 m within the Lista Formation. Top Mandal Formation was encountered at 4013.5 m, 10.5m deeper than predicted. Top Ula Formation was encountered hydrocarbon bearing from 4048 to 4209 m, which was 111 m thicker than expected. The OWC was interpreted from logs to be at 4137.0 m, while the cores taken had good oil shows all through the cored section, i.e. down to 4153 m. No reservoir sections were encountered in the Middle Jurassic. No Triassic sediments were penetrated by the well.Five cores were cut continuously from 4019 m to 4153 m with 100% recovery. Core 1 covered the lower part of the Mandal, Farsund, and the upper part of the Ula Formation. Cores 2, 3, 4 and 5 were cut in the Ula Formation. Good oil shows was observed throughout the cored section of the Ula sandstone. RFT fluid samples were taken at 4088.7 m (oil), 4137.0 m (oil), 4151 (water), and 4177 m (water).Well 2/1-9 was considered a potential water injector for the Gyda South discovery, and to be sidetracked up-dip as a producer. A full evaluation of the DST and PVT data would be performed together with a geological remapping and evaluation of the discovery. The well was thus suspended on 6 July 1991, as an oil discovery. It would be re-entered later, after the above evaluations had been completed.TestingOne DST was run in the interval 4078 - 4108 m and resulted in an oil rate of 166 Sm3 oil/day through a 32/64" choke. The gas rate was 91180 Sm3/day and the water rate was 120 Sm3/day. The GOR was 548 Sm3/Sm3 and the oil gravity was 43 deg API. Due to the presence of H2S the lower part of the Ula Formation was not tested. -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom14019.04046.0[m ]24046.04074.0[m ]34074.04102.0[m ]44102.04124.5[m ]54125.04153.0[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]133.5Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Core photos
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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 availableDST0.000.00YESDSTDST14108.004078.0014.06.1991 - 00:00YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit89181428982898291529232982305531433158316831683256361737653783380038003838385238674014401440344048404842574289 -
Composite logs
Composite logs Document nameDocument formatDocument size [MB]pdf0.50 -
Geochemical information
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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]pdf1.76pdf11.33 -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.04078410817.4Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.07.00023.600160Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.016590577549 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL CCL GR20402895CBL VDL CCL GR37614249CST GR35003947CST GR39574288DIL LLS GR03954DIL SDT GR39454298ENERJET CCL40784093ENERJET CCL40934108GR CCL27002700GR CCL40034003GR CCL41504150JUNK BASKET CCL39803980JUNK BASKET CCL42504250LDL CNL NGT39454298MWD - RWD884289OBDT GR39454298PERM PACKER40034003RFT GR SAMPLE40494243RFT SAMPLE40884088RFT SAMPLE41514151RFT SAMPLE41774177VELOCITY5004213 -
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 typeCONDUCTOR30164.036166.00.00LOTINTERM.20895.026897.01.74LOTINTERM.13 3/82893.017 1/22896.02.03LOTINTERM.9 5/83938.012 1/43940.02.15LOTLINER74275.08 1/24289.00.00LOT -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured4150.00OIL BASED4261.5742.0OIL BASED9001.04WATER BASED9611.2031.0WATER BASED15831.3949.0WATER BASED21531.6072.0WATER BASED24741.6064.0WATER BASED25291.6074.0WATER BASED26821.6073.0WATER BASED28741.6071.0WATER BASED29011.6077.0WATER BASED30181.6069.0WATER BASED31141.6068.0WATER BASED31731.607.7WATER BASED31931.6057.0WATER BASED32431.6060.0WATER BASED32531.6068.0WATER BASED33181.6076.0WATER BASED34131.6079.0WATER BASED36101.6080.0WATER BASED37751.7385.0WATER BASED38471.7377.0WATER BASED39101.7382.0OIL BASED39471.7391.0OIL BASED39671.7282.0OIL BASED40191.6251.0OIL BASED40391.5649.0OIL BASED40741.5647.0OIL BASED41021.5753.0OIL BASED41250.1453.0OIL BASED41531.5753.0OIL BASED42401.5856.0OIL BASED42891.5972.0OIL 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]PDF0.21