16/1-34 A
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General information
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Wellbore history
GeneralWell 16/1-34 A is located on the Utsira High, north of the Edvard Grieg Field in the North Sea. The primary objective was to appraise the lateral extension and producibility of the Permian Zechstein carbonates found in well 16/1-29 S. The secondary objective was to appraise the Grid Formation injectites and Heimdal Formation sandstones.Operations and resultsAppraisal well 16/1-34 A was kicked of at 555 m in the main well on 1 August 2021. It was drilled with the semi-submersible installation Deepsea Stavanger to TD at 2195 m (2024 m TVD) in the Permian Zechstein Group. The well was drilled vertical down to 543 m, then drilled towards WSW with up to ca 30 deviation at most, then dropping to 20 deviation in the bottom section. Severe mud losses (60 90 m3/hr) were encountered after coring the first core to 2067 in the Zechstein section. The well was drilled with Rheguard Prime oil-based mud from kick-off to 2047 m and with Glydril Plus mud from 2047 m to TD.The Shetland, Viking and Statfjord groups that are present in 16/1-34 S are missing in 16/1-34 A. In 16/1-34 A this interval, between 2047 m (lower V le) to 2064 (upper Zechstein), contain reworked Shetland Group chalks, possible Cromer Knoll basal conglomerates and reworked Zechstein. The Basement can be divided into a weathered section from 2104 to 2149 m and a non-weathered section below.Well 16/1-34 A encountered an oil column of about 66 metres, of which 46 metres was in Zechstein dolomite, with good reservoir quality. About 20 metres of the oil column was encountered in basement rock with poor reservoir quality. Pressure measurements acquired using XPT and ORA tools confirmed oil and water fluid gradients were present with a free-water level estimated at 2130 m (1962.8 m TVD RKB). As in the offset 16/1-29 S well, the formations (Zechstein and Basement) were found to be slightly depleted.The Grid Formation was penetrated below the hydrocarbon-water contact previously observed in the 16/1-34 S wellbore. The sandstones in 16/1-34 A had very good reservoir properties but contained only water. Sandstones of the Heimdal Member were of poorer quality than expected and were water filled. Pressure points were slightly scattered, and the formation was found to be pressure depleted.Oil shows above OBM were observed in the uppermost Heimdal Formation down to ca 1970 m, in the Zechstein section on conventional cores and sidewall cores down to 2108.5 m, and on cuttings throughout the Basement section. In the unweathered Basement the shows are weak.Four cores were cut in the well. Core 1 was cut from 2059.5 to 2067.3 m. Cores 2 to 4 were cut in succession from 2074.8 to 2079.8. total recovery for all four cores was 10.18 m (79.5%). MDT water samples were taken in the Heimdal Formation at 1975.01 m and 1985.01 m. In the Zechstein section ORA samples were taken at 2087.86 m (oil/water), 2098.86 m (oil), and 2162.13 m (water).The well was permanently abandoned on 15 September 2021 as an oil appraisal well.TestingA drill-stem test was conducted in the Zechstein section from the intervals 2057.6 to 2073.4 m and 2079.8 to 2108.5 m. The main flow produced 468 Sm3 oil, 107 Sm3 water and 48150 Sm3 gas /day through a 42/64" choke. The GOR was 103 Sm3/Sm3, the oil density at 15 C was 0.854 g/cm3 and the gas gravity was 0.84 (air=1). The gas had 0.5 ppm H2S and 0.2% CO2. The temperature at 1880.4 m was 83.6 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]560.002193.00 -
Cores at the Norwegian Offshore Directorate
Cores at the Norwegian Offshore Directorate Core sample numberCore sample - top depthCore sample - bottom depthCore sample depth - uom12059.52065.6[m ]22074.82075.6[m ]32076.12077.7[m ]42078.12079.8[m ]Cores at the Norwegian Offshore Directorate Total core sample length [m]10.2Cores at the Norwegian Offshore Directorate Cores available for sampling?YES -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit14214235575280591191110491535169217431866186618961903196919892014205820612109 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]AIT PEX HNGS XPT GR JAR14842048CMR MDT14842048CMR NEXT ADT XPT GR20472192FMI MSIP PPC GR9802192GR CCL19702141MWD - DVMT TELE SONSCOPE20452191MWD - PDORBIT ARC TELE5371478MWD - PDORBIT RAB ARC TELE ADN14842047MWD - TELE141194MWD - TELE ARC209522ORA20872162UBI URLA PEX HNGS GR20472186VSIT C1372182XLROCK GR20542165XLROCK GR20582084 -
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 typeCONDUCTOR30209.036209.00.00INTERM.20537.024543.01.74FITINTERM.13 3/81484.0161490.01.61FITLINER9 5/82046.012 1/42047.01.33FITOPEN HOLE2195.08 1/22195.00.00 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured1901.051.01.0Bentonite Spud Mud1911.3822.014.3KCL/Polymer mud5451.3522.06.2OBM6101.3932.06.5Rheguard Prime19021.4031.09.5OBM20161.4238.08.5OBM20201.3138.08.5Glydril20471.3835.08.5Rheguard Prime20671.031.01.0Other20791.0411.06.7Other20861.3117.08.5Glydril Plus21261.3215.010.5Glydril Plus21951.055.07.1WBM23841.3124.012.9Glydril Plus