17/8-1
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General information
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Wellbore history
GeneralWell 17/8-1 was drilled to test the Dovregubben prospect on the Sele High in the North Sea. The primary objective was to seek hydrocarbons in Middle Jurassic Sandnes Formation sandstones and establish its reservoir facies and quality. The secondary objective was to seek hydrocarbons in Permian Zechstein carbonates and/or Rotliegend clastics and establish their facies and quality. A third objective was to drill a section of the underlying Paleozoic stratigraphy to establish its facies and possible prospectivity.Operations and resultsA 9 7/8" shallow borehole 17/8-U-1 was drilled to check for shallow gas. It was drilled simultaneously with the top-hole sections of well 17/8-1 in a dual-drilling operation. The surface location of the shallow borehole was offset 10 m from the 17/8-1 location. No indication of shallow gas or shallow water flow was observed.Wildcat well 17/8-1was spudded with the semi-submersible installation Deepsea Stavanger on 16 September 2021 and drilled to TD at 2921 m in undifferentiated Paleozoic clastics. Operations proceeded without significant problems. The well was drilled with seawater and hi-vis pills down to 1005 m, with Rheguard Prime oil-based mud from 1005 m to 2343 m, and with Glydril Plus mud from 2343 m to TD.The well encountered 18 metres of the Sandnes and Bryne formations from the Middle Jurassic, 10 metres of which comprised sandstone with good reservoir quality. In the secondary exploration target, the well encountered about 70 metres of tight carbonate rocks in the Zechstein Group, which rest unconformably on dipping Paleozoic clastics below. Eighty-four metres of tight conglomerates, sandstone and claystone were drilled below this unconformity above well TD. It is not believed that these clastics represent the Rotliegend Group. The well also encountered 201 metres of Triassic section (Skagerrak and Smith Bank formations) the upper ca. 120 metres of which was sandstone, with poor to moderate reservoir quality. There were no oil shows in the well and gas levels were low throughout. XPT pressure points through the Jurassic and Triassic all lie on a common near hydrostatic water gradient of 1.06 g/cm3.A sidewall core from 2836.2 m in the 2-metre thick Kupferschiefer Formation showed an elevated TOC content and excellent source rock properties.No conventional coring was performed; however, extensive data acquisition was carried out including MWD/LWDand wireline logging. 30 sidewall cores were cut in the reservoir section.The well was permanently abandoned on 23 October 2021 as a dry well.TestingNo drill stem test was performed. -
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]1020.002922.00 -
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 typeCONDUCTOR30215.436215.40.00SURF.COND.13 3/81000.117 1/21005.01.82LOTPROD.9 5/82337.012 1/42343.01.97LOTOPEN HOLE2921.08 1/22921.00.00 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]FMIHD PPC MSIP PPC GR JAR18502923LWD - PDORBIT ARC ROS216996LWD - PDORBIT ARC ROS SS SADN9992333LWD - PSORBIT MI DVMT ROS SS23372917LWD - TELE140215VSI42682916XLR GR23672916XPT NEXT HRLA PEX HNGS GR JAR23382923 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit14949049087196896899410061015102510251059115414671485154015401636179022972297234623932417243524352443245524552466246625442658265828362838 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured2151.051.01.0Other10051.031.01.0Other10081.2930.08.6Rheguard Prime23431.2018.08.6Glydril PLUS29211.03Other29211.2015.010.5Glydril PLUS