31/2-12
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Generell informasjon
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Brønnhistorie
GeneralWell 31/2-12 was drilled as an appraisal well in the Troll West oil province in the Northern North Sea. The main objectives were to evaluate various techniques for gas production wells in the Troll field, to establish the reservoir quality in the central part of the Troll field gas accumulation, and to provide additional data point for the correlation and mapping of the depositional units.Operations and resultsWell 31/2-12 was spudded with the semi-submersible installation Borgny Dolphin on 26 May 1983 and drilled to TD at 1615 m in the Middle Jurassic Fensfjord Formation. On 4 June, after running the BOP-stack, operations were interrupted by a labour dispute. After the strike ended on 17 June problems with the BOP lead to a further 4 days delay before normal drilling operations were resumed. Some instability problems and well kicks were encountered while drilling and testing in the reservoir. The well was drilled with Seawater and gel down to 807 m, with KCl/polymer mud from 807 m to 1338 m, and with CaCl2/CaCO3/polymer mud from 1338 m to TD.Top reservoir in well 31/2-12 was encountered at 1365 m. The formations were interpreted to be gas bearing all through the Sognefjord Formation, the Heather Formation (1487 - 1541 m), and down to a clear GOC at 1570.5 m in the Fensfjord Formation. The upper part of the Sognefjord Formation consisted of generally clean sandstones. Below 1455 m the sands were micaceous and silty. Tight calcareous streaks occurred over the whole section. Oil was interpreted from 1570.5 m down to 1581.0 m, where an abrupt drop in resistivity was interpreted as the oil/water contact. The contact was somewhat obscured however by a change in lithology from clean, but rather tight, sandstone to micaceous sandstone. No movable oil was calculated below this depth, but shows (fluorescence and cut) was observed on sidewall cores down to 1608 m.Ten cores were cut in the Late Jurassic Sognefjord reservoir section. From a total of 89.5 m in the intervals 1366 - 1424 m and 1427 - 1458.5 m 86.7 m core (97%) was recovered. All cores were taken using fibreglass sleeve techniques to achieve better recovery in the poorly consolidated sands. Two gas samples were recovered from the uppermost reservoir section during RFT run 1. Recovery of an oil sample during RFT run 2 failed because of plugging by chalk particles in the mud cake. During a separate run with a modified "long nose" RFT probe an oil sample from the thin oil column at 1576 m was obtained.The well was permanently abandoned on 9 September 1983 as an oil and gas appraisal well.TestingTwo intervals in the clean sands were tested. From 1428 to 1452 m the well bore was underreamed to 16 inch and completed with an external gravel pack (E6P). This test (PT1) produced 563700 Sm3 gas/day through a 17.5" choke. A second test (PT-2) used an internal gravel pack (IGP) over the interval from 1385 to 1405 m. During this test the well took a kick and had to be closed in. The production-string was cut and the well killed. After fishing out the production string a successful gravel pack test was performed. This test produced 684100 Sm3 gas/day through a 17.5" choke. The gas produced in the tests was dry (gas gravity = 0.61) with a gas/condensate ratio of 35622 Sm3/Sm3. The condensate produced had a gravity of 51 degAPI. The gas contained 1.5% N2, 0.6% C02 and 0.05 ppm H2S. The maximum down-hole temperatures measured in the two tests were 62.8 and 61.7 deg C in PT1 and PT2, respectively. -
Borekaks i Sokkeldirektoratet
Borekaks i Sokkeldirektoratet Borekaks tilgjengelig for prøvetaking?YESBorekaks i Sokkeldirektoratet Borekaksprøve, topp dybde [m]Borekaksprøve, bunn dybde [m]480.001615.00 -
Borekjerner i Sokkeldirektoratet
Borekjerner i Sokkeldirektoratet Kjerneprøve nummerKjerneprøve - topp dybdeKjerneprøve - bunn dybdeKjerneprøve dybde - enhet11366.01375.5[m ]21375.01378.7[m ]31380.01386.0[m ]41389.01398.2[m ]51398.01407.2[m ]61407.01416.0[m ]71416.01424.2[m ]81427.01436.0[m ]91436.01449.0[m ]101449.01458.5[m ]Borekjerner i Sokkeldirektoratet Total kjerneprøve lengde [m]86.3Borekjerner i Sokkeldirektoratet Kjerner tilgjengelig for prøvetaking?YES -
Kjernebilder
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Oljeprøver i Sokkeldirektoratet
Oljeprøver i Sokkeldirektoratet Test typeFlaske nummerTopp dyp
MD [m]Bunn dyp
MD [m]Væske typeTest tidspunktPrøver tilgjengeligDSTDST11428.001452.00CONDENSATE30.07.1983 - 00:00YES -
Litostratigrafi
Litostratigrafi Topp Dyb [mMD RKB]Litostrat. enhet359730118111811234125813541365136514871541 -
Dokumenter – eldre Sokkeldirektoratets WDSS rapporter og andre relaterte dokumenter
Dokumenter – eldre Sokkeldirektoratets WDSS rapporter og andre relaterte dokumenter Dokument navnDokument formatDokumentstørrelse [MB]pdf0.19pdf0.18 -
Dokumenter – rapportert av utvinningstillatelsen (frigitt ihht til regelverk)
Dokumenter – rapportert av utvinningstillatelsen (frigitt ihht til regelverk) Dokument navnDokument formatDokumentstørrelse [MB]PDF11.38pdf0.11pdf1.50pdf0.68pdf1.18pdf4.07pdf5.81pdf1.13pdf1.55pdf0.65pdf1.18pdf2.85pdf13.78pdf23.30 -
Borestrengtester (DST)
Borestrengtester (DST) Test nummerFra dybde MD
[m]Til dybde MD
[m]Reduksjonsventil størrelse
[mm]1.01428145217.52.01385140517.5Borestrengtester (DST) Test nummerEndelig avstengningstrykk
[MPa]Endelig strømningstrykk
[MPa]Bunnhullstrykk
[MPa]Borehullstemperatur
[°C]1.02.0Borestrengtester (DST) Test nummerOlje produksjon
[Sm3/dag]Gass produksjon
[Sm3/dag]Oljetetthet
[g/cm3]Gasstyngde rel. luftGOR
[m3/m3]1.05640002.0684000 -
Logger
Logger Type loggTopp dyp for logg [m]Bunn dyp for logg [m]BGT GR14231453CBL7971428CNL13651419CNL GP13351405CNL NGT13371423CST13371423CST14241507CST15091604DLL MSFL CAL GR14241615DLL MSFL GR13371423DLL MSFL GR14241460GR12401424GR CCL SH13001340GR CCL SH13001350GR ISF13371423HDT14241614ISF BHC GR458551ISF BHC GR551806ISF BHC GR8011336ISF BHC GR14241613LDT CNL CAL NGT14241614LDT CNL GR CAL458552LDT CNL GR CAL551807LDT CNL GR CAL8011338LDT GR CAL13371423LDT GR CAL14241460RFT HP13681408RFT HP14721600SHDT GR14241614SONIC GR CBL VDL13371423WST6081610 -
Foringsrør og formasjonsstyrketester
Foringsrør og formasjonsstyrketester Type utforingUtforing diam.
[tommer]Utforing dybde
[m]Brønnbane diam.
[tommer]Brønnbane dyp
[m]LOT/FIT slam eqv.
[g/cm3]Type formasjonstestCONDUCTOR30458.036468.00.00LOTSURF.COND.20802.026810.01.54LOTINTERM.13 3/81338.017 1/21348.01.63LOTINTERM.9 5/81424.012 1/41427.00.00LOTOPEN HOLE1600.08 1/21615.00.00LOT -
Boreslam
Boreslam Dybde MD [m]Egenvekt, slam [g/cm3]Viskositet, slam [mPa.s]Flytegrense [Pa]Type slamDato, måling3601.04100.0water based6001.0484.0water based8501.2554.0water based10001.2854.0water based11001.3154.0water based15001.2863.0water based -
Trykkplott
Trykkplott Porertrykksdataene kommer fra logging i brønnen hvis ingen annen kilde er oppgitt. I noen brønner der trykk ikke er logget, er det brukt informasjon fra formasjonstester eller brønnspark. Trykkdataene er rapportert inn til Oljedirektoratet og videre prosessert og kvalitetssikret av IHS Markit.Trykkplott Dokument navnDokument formatDokumentstørrelse [MB]pdf0.17