2/6-5
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Generell informasjon
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Brønnhistorie
GeneralBlock 2/6 is structurally located on the eastern margin of the Norwegian part of the Feda Graben. The block partly covers the Piggvar Terrace, the metamorphic Mandal high and the northwestern part of the Søgne basin.Well 2/6-5 is located in the central western part of the block, high on a structural closure defined on Top Shetland GroupThe main objective of well 2/6-5 was to test the presence of hydrocarbons and reservoir properties within the primary target intervals of the Shetland Group, located within a structural closure above the northern part of the Mandal High. It was prognosed approximately 40 m below the distinct Late Cretaceous Top Ekofisk Formation reflector.Reservoir units were expected in several intervals, some in pressure communication and some not. A possible secondary target of sediment fill in the interval between the Shetland Group and the basement topography would be penetrated before reaching TD in metamorphic rocks. However, this possible wedge was defined on a poor seismic response and could represent intra basement reflectivity. The well was planned as a possible future producer.Operations and resultsExploration well 2/6-5 was spudded by the semi-submersible installation "Deepsea Bergen" 17 November 1996 and drilled to TD at 3260 m in metamorphic rocks. The well was drilled with a sea water/bentonite mud system down through the 12 1/2" hole section to 2515 m. The deeper part of the well was drilled with a KCL polymer glycol mud system.Above the Shetland Group the formation tops and lithologies were drilled within the uncertainty limits of the prognosis. The Tertiary succession (including Quaternary) was found to be 2872 m thick. The Nordland Group was 1404.7 m thick and consisted of clay/claystones and sands. Top of the Hordaland Group was encountered at 1499.5 m and the Group was found to be 1229.4 m thick, generally consisting of reactive clays. Top Rogaland Group was drilled at 2729 m Top. The Rogaland succession contained Balder, Sele/Lista, and Våle Formations and was 88 m thick. Top of the Shetland Group was drilled at 2817 m. Top Tor Formation was drilled at 2897.5 m.The Shetland Group interval velocity was experienced to be much higher than the prognosis based on stacking velocities indicated. The explanation to the observed discrepancy in seismic velocities contra the experienced well velocities is explained as azimuthal anisotropy combined with the seismic sampling configuration. The result is a reasonable seismic tie in two-way travel time to the well, but a significant mismatch in depth prognosis for the Top Hod and deeper strata.Top Hod Formation was prognosed at 3015 +/- 75 m and was drilled at 3155 m. The Base Cretaceous Unconformity was prognosed at 3103 +/- 125 m and was drilled at 3230.5 m (+125.5m). The secondary target, defined as a possible wedge resting on basement turned out not to be present and the seismic image had to be considered as intra basement reflectivity. Logs and core data both conclude that a rather tight chalk lithology is present in the well. Only few intervals of allochthonous chalk were observed. Immediately below the chalk interval, only separated by thin clay unit (altered basement rocks), fractured metamorphic basement consisting of chists were penetrated. A short core was cut, confirming oil shows in fractures within the basement rocks.Weak oil shows were reported from the Ekofisk Formation (2817-2897.5 m), and one core was cut. Six more cores were cut in the Tor Formation (2897.5- 3155 m). The cores had variable recovery, especially in core # 6 with only 7.5 % recovery. In addition to the weak shows reported from the Ekofisk Formation, shows were observed in fractures both in the Tor Formation and in the Basement. Matrix staining was only seen within the Tor Formation, in zones of less than 30 cm thickness in the interval from 2929 to 2935 m. A Modular Formation Dynamics Tester (MDT) with a RPQS gauge was used to obtain formation pressure measurements and fluid samples. Due to very tight formation, the pressure measurements were of questionable quality. Two segregated samples were taken at respectively 2929.5 m and 2951.5 m. Two multi samples chambers and one 1 gal chamber were taken at 3026.3 m. Unfortunately, the obtained MDT fluid samples were not representative due to mud contamination and low chamber pressure at shut-in. The MDT fluid sample from 2929.5 m contained 1: 3 oil/water. Only water was retrieved in the samples from 2951.5 and 3026.3 m. The water samples held a high concentration of Na, Ca, K, and Cl. These concentrations can partly be explained by mud invasion of KCl mud. The remaining salinity has to be explained as abnormal NaCl concentrations, which complicates the petrophysical well evaluation. Based on the limited pressure information and log interpretation an OWC was indicated at 2944.8 m (2942.8 m TVD RKB).After a drill stem test lasting from 24 December 1996 to 8 January 1997 the well was permanently abandoned as an oil discovery on 11 January.TestingA drill stem test with two perforated intervals (2955-2948 m and 2941-2929 m) within the Tor Formation was conducted. The test results show a very tight reservoir with a test permeability of 0.4 mD. No indications of natural fractures were observed. After acid stimulation (LCA acid frac.), the perforated intervals produced water with 3% oil content at a stable rate. The test was shut in after a flow period of 46 hours. The reservoir pressure was 447 bar and the temperature 117.3 deg C at mid-perforation (2938.5 m). -
Borekaks i Sokkeldirektoratet
Borekaks i Sokkeldirektoratet Borekaks tilgjengelig for prøvetaking?YESBorekaks i Sokkeldirektoratet Borekaksprøve, topp dybde [m]Borekaksprøve, bunn dybde [m]820.003252.00 -
Borekjerner i Sokkeldirektoratet
Borekjerner i Sokkeldirektoratet Kjerneprøve nummerKjerneprøve - topp dybdeKjerneprøve - bunn dybdeKjerneprøve dybde - enhet12852.02854.0[m ]22904.02917.0[m ]32929.02934.7[m ]42935.02953.0[m ]52953.02956.8[m ]62957.02958.5[m ]72977.02980.1[m ]83252.03254.1[m ]Borekjerner i Sokkeldirektoratet Total kjerneprøve lengde [m]49.1Borekjerner i Sokkeldirektoratet Kjerner tilgjengelig for prøvetaking?YES -
Kjernebilder
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Palynologiske preparater i Sokkeldirektoratet
Palynologiske preparater i Sokkeldirektoratet Prøve dybdeDybde enhetPrøve typeLaboratorie2410.0[m]DCUNIVSHET2430.0[m]DCUNIVSH2450.0[m]DCUNIVSH2470.0[m]DCUNIVSH2490.0[m]DCUNIVSH2510.0[m]DCUNIVSH2530.0[m]DCUNIVSH2550.0[m]DCUNIVSH2570.0[m]DCUNIVSH2590.0[m]DCUNIVSH2610.0[m]DCUNIVSH2630.0[m]DCUNIVSH2650.0[m]DCUNIVSH2670.0[m]DCUNIVSH2690.0[m]DCUNIVSH2709.0[m]DCUNIVSH2727.0[m]DCUNIVSH2730.0[m]DCUNIVSH2733.0[m]DCUNIVSH2748.0[m]DCUNIVSH2769.0[m]DCUNIVSH2787.0[m]DCUNIVSH2802.0[m]DCUNIVSH2811.0[m]DCUNIVSH2814.0[m]DCUNIVSH3228.0[m]DCUNIVSH3237.0[m]DCUNIVSH3246.0[m]DCUNIVSH3257.0[m]DCUNIVSH -
Oljeprøver i Sokkeldirektoratet
Oljeprøver i Sokkeldirektoratet Test typeFlaske nummerTopp dyp
MD [m]Bunn dyp
MD [m]Væske typeTest tidspunktPrøver tilgjengeligDSTDST10.000.0004.01.1997 - 14:00YES -
Litostratigrafi
Litostratigrafi Topp Dyb [mMD RKB]Litostrat. enhet9315002729272927382777280928172817289831553231 -
Spleisede logger
Spleisede logger Dokument navnDokument formatDokumentstørrelse [MB]pdf0.44 -
Dokumenter – rapportert av utvinningstillatelsen (frigitt ihht til regelverk)
Dokumenter – rapportert av utvinningstillatelsen (frigitt ihht til regelverk) Dokument navnDokument formatDokumentstørrelse [MB]pdf9.96pdf26.87 -
Borestrengtester (DST)
Borestrengtester (DST) Test nummerFra dybde MD
[m]Til dybde MD
[m]Reduksjonsventil størrelse
[mm]1.02955291911.1Borestrengtester (DST) Test nummerEndelig avstengningstrykk
[MPa]Endelig strømningstrykk
[MPa]Bunnhullstrykk
[MPa]Borehullstemperatur
[°C]1.044.00030.000117Borestrengtester (DST) Test nummerOlje produksjon
[Sm3/dag]Gass produksjon
[Sm3/dag]Oljetetthet
[g/cm3]Gasstyngde rel. luftGOR
[m3/m3]1.080.831 -
Logger
Logger Type loggTopp dyp for logg [m]Bunn dyp for logg [m]DSI DLL NGT GR ACTS24903257FMI24903257FMI GR ACTS28322993LDT DSI BGT GR ACTS8022519MDT GR ACTS28002968MDT GR ACTS29512951MDT GR ACTS30203026MDT GR AMS28322993MWD - GR RES DIR1703260PEX CMR ACTS24233257VSP16893159 -
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 formasjonstestCONDUCTOR30170.036170.00.00LOTSURF.COND.13 3/8802.017 1/2805.01.82LOTINTERM.9 5/82494.012 1/42496.01.78LOTLINER73260.08 1/23260.00.00LOT -
Boreslam
Boreslam Dybde MD [m]Egenvekt, slam [g/cm3]Viskositet, slam [mPa.s]Flytegrense [Pa]Type slamDato, måling1301.03WATER BASED7091.04WATER BASED8080.00WATER BASED10861.3524.0WATER BASED25151.6036.0WATER BASED28011.6044.0WATER BASED29041.6038.0WATER BASED29191.6039.0WATER BASED29551.6232.0WATER BASED29841.6130.0WATER BASED31291.6032.0WATER BASED31761.6039.0WATER BASED32521.6038.0WATER BASED32601.62WATER BASED -
Tynnslip i Sokkeldirektoratet
Tynnslip i Sokkeldirektoratet DybdeEnhet3231.00[m ]3234.00[m ]3237.00[m ]3240.00[m ]3243.00[m ]3246.00[m ]3249.00[m ]3252.00[m ]3253.00[m ]3254.00[m ] -
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]pdf0.21