25/11-6
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General information
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Wellbore history
GeneralWell 25/11-6 was drilled ca 1 km west of the 25/11-1 Balder discovery well on the Utsira High in the North Sea. The primary objective was to delineate the Paleocene E-70 oil sand and older sands which are developed as topographic mounds (stratigraphic traps) in the Balder Field area. A secondary objective was Danian sand which had oil shows in an offset well.Operations and resultsAppraisal well 25/11-6 was spudded with the semi-submersible installation Norskald on 20 August 1978 and drilled to TD at 1948 m in the Early Cretaceous Cromer Knoll Group. The well was drilled with seawater/gel/lignosulphonate.The well penetrated the Utsira Formation, a Skade Formation sand and a Grid Formation sand and then penetrated a ca 175 m thick section of shales belonging to the lower Hordaland Group before top Balder formation was encountered at 1646 m. An 8 m thick shaly Intra Balder Formation sand at 1664 m had some shows and appeared to be oil bearing on the logs. Two Paleocene Heimdal Formation sand units with tops at 1717.5 m and 1763.0 m were found oil bearing down to a clear oil-water contact at 1785.3 m in the lower sand unit. This defines the OWC of the Balder field at 1760 m MSL. The Danian sand (Ty Formation) was encountered at 1877 m, but was water wet.Five cores were cut in the Lista and Heimdal Formation, recovering a total of 25.5 m core from the interval 1713 to 1797 m. Wire line fluid samples were attempted, but with no success.The well was permanently abandoned on 1 October 1978 as an oil appraisal.TestingOne production test was performed in the interval 1725 to 1740 m in the upper Heimdal Formation sand unit. It produced 485 Sm3 oil and 18123 Sm3 gas with 3-4% sand/day through a 35/64" choke. The GOR was 37 Sm3/Sm3, the oil gravity was 24.3 deg API, and the gas gravity was 0.61 (air = 1). No H2S or Inert gas was detected. -
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]200.001945.00 -
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 availableDSTDST11725.001740.0021.09.1978 - 00:00YES -
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 typeCONDUCTOR30187.036187.00.00LOTINTERM.13 3/8394.017 1/2410.00.00LOTINTERM.9 5/81310.012 1/41327.00.00LOTLINER71927.08 1/21948.00.00LOT -
Drill stem tests (DST)
Drill stem tests (DST) Test numberFrom depth MD
[m]To depth MD
[m]Choke size
[mm]1.01725174013.9Drill stem tests (DST) Test numberFinal shut-in pressure
[MPa]Final flow pressure
[MPa]Bottom hole pressure
[MPa]Downhole temperature
[°C]1.017.600Drill stem tests (DST) Test numberOil
[Sm3/day]Gas
[Sm3/day]Oil density
[g/cm3]Gas grav. rel.airGOR
[m3/m3]1.048518000000.9000.600210 -
Logs
Logs Log typeLog top depth [m]Log bottom depth [m]CBL VDL2991302CCL GR16121785DLL13091945FDC CNL13041948GR152405HDT13091947ISF SONIC186405ISF SONIC3941308ISF SONIC MSFL13011948TEMP1081757VELOCITY01948 -
Lithostratigraphy
Lithostratigraphy Top depth [mMD RKB]Lithostrat. unit1516087307527521011108011001462147116461646166416721688170217181848186418771903190319081932 -
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]pdf1.01pdf156.00 -
Drilling mud
Drilling mud Depth MD [m]Mud weight [g/cm3]Visc. [mPa.s]Yield point [Pa]Mud typeDate measured9951.13waterbased17871.13waterbased19471.14waterbased -
Palynological slides at the Norwegian Offshore Directorate
Palynological slides at the Norwegian Offshore Directorate Sample depthDepth unitSample typeLaboratory1150.0[m]DC1180.0[m]DC1210.0[m]DC1230.0[m]DC1260.0[m]DC1290.0[m]DC1320.0[m]DC1346.5[m]SWC1350.0[m]DC1400.0[m]DC1410.0[m]DC1430.0[m]DC1440.0[m]DC1460.0[m]DC1480.0[m]DC1490.0[m]DC1500.0[m]DC1510.0[m]DC1520.0[m]DC1540.0[m]DC1560.0[m]DC1570.0[m]DC1590.0[m]DC1600.0[m]DC1610.0[m]DC1630.0[m]DC1652.0[m]SWC1656.0[m]SWC1669.0[m]SWC1673.0[m]SWC1675.0[m]SWC1679.0[m]SWC1684.0[m]DC1684.5[m]SWC1690.0[m]DC1690.5[m]SWC1692.5[m]SWC1696.0[m]DC1697.0[m]SWC1702.0[m]DC1704.5[m]SWC1707.0[m]DC1708.0[m]DC1711.0[m]SWC1713.0[m]DC1714.0[m]DC1716.0[m]C1716.0[m]C1716.0[m]SWC1726.0[m]SWC1750.0[m]DC1751.7[m]DC1751.7[m]C1752.0[m]SWC1753.0[m]DC1753.2[m]C1753.3[m]C1754.0[m]SWC1754.7[m]C1756.0[m]DC1756.8[m]DC1756.8[m]C1757.0[m]DC1759.0[m]SWC1760.0[m]SWC1761.0[m]SWC1762.0[m]SWC1762.0[m]DC1767.0[m]DC1772.0[m]DC1776.0[m]SWC1780.0[m]DC1792.0[m]DC1798.0[m]DC1804.0[m]DC1810.0[m]DC1816.0[m]DC1822.0[m]DC1828.0[m]DC1834.0[m]DC1840.0[m]DC1846.0[m]DC1851.0[m]SWC1852.0[m]DC1856.0[m]SWC1858.0[m]DC1863.0[m]SWC1864.0[m]DC1868.5[m]SWC1870.0[m]DC1871.0[m]SWC1876.0[m]DC1882.0[m]DC1900.0[m]DC1906.0[m]DC1909.0[m]DC1912.0[m]DC1945.0[m]DC