Wellbore: 02.01.2024 - 31/2-5 - Factpages - Norwegian Offshore Directorate

General information

General information
Attribute	Value
Wellbore name Official name of wellbore based on Norwegian Offshore Directorate guidelines for designation of wells and wellbores.	31/2-5
Type Wellbore type. Legal values: EXPLORATION, DEVELOPMENT, OTHER (see 'Purpose' for more information)	EXPLORATION
Purpose Final classification of the wellbore. Legal values for exploration wellbores: WILDCAT, APPRAISAL, WILDCAT-CCS, APPRAISAL-CCS. Legal values for development wellbores: OBSERVATION, PRODUCTION, INJECTION, INJECTION-CCS, OBSERVATION-CCS. Legal values for other wellbores: SOIL DRILLING (drilling in connection with track surveys and other subsurface surveys to investigate the soil conditions prior to placement of facilities), SHALLOW GAS (drilling to investigate shallow gas before the first 'real' drilling on the location), PILOT (drilling to investigate the geology and fluid connectors for location of the main wellbore), SCIENTIFIC (drilling according to Law of Scientific research and exploration), STRATIGRAPHIC (driling according to Law of Petroleum activities §2-1).	APPRAISAL
Status Status for the wellbore. Legal values are: BLOWOUT: A blowout has occurred in the well. CLOSED: A development wellbore that has been closed in a shorter or longer periode. Also applies to development wellbores where drilling is completed, but production/injection has not yet been reported. DRILLING: The well is in the drilling phase - can be active drilling, logging, testing or plugging, JUNKED: The drilling operation has been terminated due to technical problems. P&A: Exploration: The well is plugged and abandoned, and can not be reentered for further use. Development wells: The production/injection from/to the well is stopped and the well is plugged. The wellhead is removed or else made unavailable for further well operations. PLUGGED: The wellbore has been plugged, but the upper parts of the wellbore can be re-used. A sidetrack might be drilled at a later stage. PRODUCING: It was produced from the wellbore at the time of the operators last monthly report to the Norwegian Offshore Directorate. INJECTING: It was injected to the wellbore at the time of the operators last monthly report to the Norwegian Offshore Directorate. PREDRILLED: The upper part of the well has been drilled, usually as part of a batch-drilling campaign covering several wellbores. RE-CLASS TO DEV: Exploration wellbore that is reclassified to a development wellbore. RE-CLASS TO TEST: Exploration wellbore that is reclassified to test production. SUSPENDED: The drilling operation in the wellbore has been temporarily stopped. The current plan is to continue drilling later on.	SUSPENDED
Factmaps in new window	link to map
Main area Name of the area on the Norwegian Continental Shelf where the wellbore is located. Legal values: BARENTS SEA, NORWEGIAN SEA, NORTH SEA.	NORTH SEA
Field Name of the field the wellbore is related to.	TROLL
Discovery Name of the discovery the wellbore is related to.	31/2-1 (Troll Vest)
Well name Official name of the parent well for the wellbore based on Norwegian Offshore Directorate guidelines for designation of wells and wellbores.	31/2-5
Seismic location Position of spud location on seismic survey lines. SP: shotpoint.	79421 SP. 274
Production licence Official designation of the production licence the wellbore was drilled or planned to be drilled from ( well head posistion).	054
Drilling operator Name of the licensee starting the drilling operation on behalf of the active production license (well head position). This will usually equal the operator of the production license.	A/S Norske Shell
Drill permit The drilling permit number together with the version of the drilling permit as stated in the drilling permit granted by the Norwegian Offshore Directorate.	263-L
Drilling facility Norwegian Offshore Directorate's name of the facility which the wellbore was drilled from.	WEST VENTURE OLD
Drilling days Number of days from wellbore entry to wellbore completion.	57
Entered date The date when he wellbore was spudded. For sidetracks: The date when new formation was drilled by kicking off from the mother-wellbore,	26.10.1980
Completed date Exploration wellbores from moveable facilities: For floating facilities - date when anchor handling is started. For jackups - date the jacking-down started. Exploration wellbores from fixed facilities and all development wellbores: Date when the wellbore is at total depth, and last casing, liner or screen is set. In case of immediate plugging of the wellbore, completed date equals the date the last plug i set in the wellbore. Date when the wellbore is at total depth, and last casing, liner or screen is set. In case of immediate plugging of the wellbore, completed date equals the date the last plug i set in the wellbore.	21.12.1980
Release date Date when raw data which has been reported to the authorities from the wellbore is not confidential any longer. Normally 2 years after finishing the drilling. May be earlier if the area of the production license is relinquished.	21.12.1982
Publication date Date quality control of the wellbore information was completed, so it can be published on the internet as a 'Well Data Summary Sheet' wellbore with more information available than other wellbores.	07.11.2005
Purpose - planned Pre-drill purpose of the wellbore. Legal values for exploration wellbores: WILDCAT, APPRAISAL, WILDCAT-CCS, APPRAISAL-CCS. Example of legal values for development wellbores: OBSERVATION, PRODUCTION, INJECTION.	WILDCAT
Reentry Status whether the wellbore has been re-entered (YES) or not (NO). Re-entered wellbores are not included in the count when wellbores are presented in statistical overviews.	NO
Content For exploration wellbores, status of discovery. Legal values: DRY, SHOWS (trace amounts of hydrocarbons), GAS, GAS/CONDENSATE, OIL or OIL/GAS. SHOWS (GAS SHOWS, OIL SHOWS or OIL/GAS SHOWS) are detected as fluorescent cut (organic extract), petroleum odour, or visual stain on cuttings or cores, or as increased gas reading on the mud-loggers gas detection equipment. Legal values for WILDCAT-CCS and APPRAISAL-CCS: WATER For development wellbores, type of produced/injected fluid. Legal values: WATER, CUTTINGS, NOT AVAILABLE, OIL, GAS/CONDENSATE, OIL/GAS, CO2, GAS, WATER/GAS, NOT APPLICABLE.	OIL/GAS
Discovery wellbore Indicator which tells if the wellbore made a new discovery. Legal values: YES, NO. Prior to press-release or other information regarding drilling results, the indicator will be “NO” as a default.	NO
1st level with HC, age Age of lithostratigraphic unit, 1st level, where hydrocarbons were encountered. Examples of legal values: CRETACEOUS, EARLY CRETACEOUS, LATE JURASSIC, EOCENE. See also Norwegian Offshore Directorate bulletins.	LATE JURASSIC
1st level with HC, formation Name of lithostartigraphic unit, 1st level, where hydrocarbons were encountered. Shown only for released wells. Examples of legal values: BASEMENT, COOK FM, EKOFISK FM, HEIMDAL FM, SANDNES FM, SOGNEFJORD FM, TARBERT FM, BRENT GP. See also Norwegian Offshore Directorate bulletins.	SOGNEFJORD FM
Kelly bushing elevation [m] Elevation of the rotary kelly bushing (RKB) above mean sea level.	32.0
Water depth [m] Depth in metres betweem mean sea level and sea floor.	333.0
Total depth (MD) [m RKB] Total measured length of wellbore from kelly bushing to total depth (driller's depth).	2532.0
Final vertical depth (TVD) [m RKB] Vertical elevation from total depth to kelly bushing. Shown only for released wells. Referred to as true vertical depth (TVD).	2532.0
Maximum inclination [°] Maximum deviation, in degrees, from a vertical well path.Shown only for released wells.	1.5
Bottom hole temperature [°C] Estimated temperature at final total depth of the wellbore. Shown only for released wells. See discription.	79
Oldest penetrated age Age (according to Geologic Time Scale 2004 by F. M. Gradstein, et al. (2004)) of the oldest penetrated formation. May differ from age at TD for example in deviated wellbores. Examples of legal values: CRETACEOUS, EARLY CRETACEOUS, LATE JURASSIC, EARLY PERMIAN, EARLY TRIASSIC, EOCENE.	TRIASSIC
Oldest penetrated formation Name of the oldest lithostratigraphic unit penetrated by the wellbore. Shown only for released wells. In most wellbores this is formation or group at total depth. May differ from formation or group at TD for example in wellbores drilled with high deviation or through faults. Examples of legal values: AMUNDSEN FM, BALDER FM, BASEMENT, BLODØKS FM, BRYNE FM, BURTON FM, COOK FM, DRAKE FM, DRAUPNE FM, EKOFISK FM, DUNLIN GP.	HEGRE GP
Geodetic datum Reference system for coordinates. Example of legal values: ED50.	ED50
NS degrees Geographic coordinate of the wellhead, north-south degrees.	60° 46' 16.2'' N
EW degrees Geographic coordinate of the wellhead, east-west degrees.	3° 25' 53.46'' E
NS UTM [m] Universal Transverse Mercator coordinate of the wellhead, north-south.	6737535.76
EW UTM [m] Universal Transverse Mercator coordinate of the wellhead, east-west.	523507.71
UTM zone Universal Transverse Mercator zone. Examples of legal values: 31, 32, 33, 34.	31
NPDID wellbore Norwegian Offshore Directorate's unique id for the wellbore.	210

Wildcat well 31/2-5 is located in the southern part of the oil province in the Troll West area, some 6 km west of the discovery well 31/2-1, in a downthrown fault block. The objectives of the well were to test presence and nature of hydrocarbons in a structure west of the main gas reservoir; to test lateral variation in reservoir characteristics westwards; to investigate possible causes for the difference in flat spot appearance in this fault block; and to get a good geologic identification of the various seismic reflectors for lateral extrapolation of well data.

Operations and results

Problems were experienced during positioning and anchoring of semi-submersible installation West Venture for the wildcat well 31/2-5. After 6 days efforts the installation had to be repositioned 25 m from the intended location and the anchors were successfully laid out and tensioned. The well was spudded on 26 October 1980 and drilled to TD at 2532 m in the Triassic Hegre Group. The well was drilled with seawater and viscous pills down to 443 m, with gelled seawater from 443 m to 810 m, with KCl/polymer mud from 810 m to 1807 m, and with seawater/gel from 1807 m to TD.

Well 31/2-5 confirmed that the Late Jurassic Sognefjord Formation sandstone reservoir was well developed also in the western part of the structure. A gas column was penetrated from 1536 m to 1579 m (43 m), followed by a 21 m thick oil column down to an OWC at 1600 m. Good oil shows continued down to 1644.5 m. The GOC was found at the same depth as seen in the other wells in the area. The most interesting observation in this well was the presence of the thick oil column below the gas, some 9 m thicker than seen in any of the other wells, and the oil was encountered in a section of the reservoir with very good clean sand. It is yet too early to explain the difference in oil thickness, and the importance of a thicker oil column in a good sand will remain unknown until a full production test of the oil has been carried out. A few carbonate cemented, apparently field-wide bands occur with very low poroperm values. A seal over the structure is provided by the Paleocene claystones.

A total of 21 cores (125.8 m) were cut using five Christensen core heads with a total recovery of 98.51 m (78%) from 1511.7 - 1652 m. RFT sampling of pressure points and two successful fluid samples (gas at 1578 m and oil/gas at 1597 m) were consistent with the fluid contacts assessed from the electrical logs. The oil sampled from 1597 m had a gravity of 30.5 deg API compared to 25 deg API in other 31/2 wells.

The well was plugged from 1204 m to 1465 m and suspended on 21 December 1980 as an oil and gas appraisal well.

Testing

No drill stem test was performed.

Cuttings at the Norwegian Offshore Directorate

Cuttings at the Norwegian Offshore Directorate
Cuttings available for sampling?	YES

Cuttings at the Norwegian Offshore Directorate
Cutting sample, top depth [m]	Cutting samples, bottom depth [m]
450.00	2532.00

Cores at the Norwegian Offshore Directorate

Cores at the Norwegian Offshore Directorate
Core sample number	Core sample - top depth	Core sample - bottom depth	Core sample depth - uom
1	1511.7	1514.3	[m ]
2	1514.8	1517.4	[m ]
4	1536.0	1538.0	[m ]
5	1539.5	1540.5	[m ]
6	1542.0	1545.6	[m ]
7	1547.0	1563.7	[m ]
8	1555.0	1555.2	[m ]
9	1555.5	1564.5	[m ]
10	1565.0	1573.4	[m ]
11	1573.4	1573.9	[m ]
12	1573.9	1577.4	[m ]
13	1589.5	1589.6	[m ]
14	1590.5	1599.5	[m ]
15	1599.5	1604.0	[m ]
16	1604.0	1611.9	[m ]
17	1613.0	1615.4	[m ]
18	1616.0	1625.0	[m ]
19	1625.0	1633.4	[m ]
20	1634.0	1642.9	[m ]
21	1643.0	1651.6	[m ]

Cores at the Norwegian Offshore Directorate
Total core sample length [m]	108.5

Cores at the Norwegian Offshore Directorate
Cores available for sampling?	YES

Core photos

Core photos

1512-1513m	1515-1516m	1536-1538m	1539-1540m	1542-1544m

1544-1545m	1547-1549m	1549-1552m	1555-1555m	1552-1553m

1555-1558m	1558-1560m	1560-1563m	1563-1564m	1565-1567m

1567-1570m	1570-1573m	1573-1573m	1573-1574m	1573-1576m

1576-1577m	1589-1589m	1590-1593m	1593-1595m	1595-1598m

1598-1599m	1599-1602m	1602-1604m	1604-1606m	1606-1609m

1609-1611m	1613-1615m	1616-1618m	1618-1621m	1621-1624m

1624-1625m	1625-1627m	1627-1630m	1630-1633m	1633-1633m
			$Core photo at depth: 1642-1643m$
1634-1636m	1636-1639m	1639-1642m	1642-1643m	1643-1645m

1645-1648m	1648-1651m	1651-1652m

Lithostratigraphy

Lithostratigraphy
Top depth [mMD RKB]	Lithostrat. unit
365	NORDLAND GP
788	HORDALAND GP
788	NO FORMAL NAME
815	NO FORMAL NAME
1346	ROGALAND GP
1346	BALDER FM
1396	SELE FM
1426	LISTA FM
1533	SHETLAND GP
1536	VIKING GP
1536	SOGNEFJORD FM
1617	HEATHER FM
1693	FENSFJORD FM
1789	KROSSFJORD FM
1860	HEATHER FM
1957	BRENT GP
2070	DUNLIN GP
2070	DRAKE FM
2201	COOK FM
2277	AMUNDSEN FM
2308	JOHANSEN FM
2387	AMUNDSEN FM
2404	STATFJORD GP
2471	HEGRE GP

Composite logs

Composite logs
Document name	Document format	Document size [MB]
210	pdf	0.32

Documents – older Norwegian Offshore Directorate WDSS reports and other related documents

Documents – older Norwegian Offshore Directorate WDSS reports and other related documents
Document name	Document format	Document size [MB]
210_01_WDSS_General_Information	pdf	0.15
210_02_WDSS_completion_log	pdf	0.18

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 name	Document format	Document size [MB]
210_01_Drilling_programme	pdf	1.18
210_02_Drilling_programme_enclosure	pdf	1.01
210_03_Final_Well_Report_by_EXLOG	pdf	7.30
210_04_Well_resume_by_Shell	pdf	1.36
210_05_Well Summary_by_Anchor	pdf	1.58
210_06_Biostratigraphy_appendix_3_by_Corelab	pdf	4.06
210_07_Final_Core_report_core_1-21_by_GECO	pdf	2.90
210_08_Evaluation_of_core_data_by_Geco	pdf	9.86
210_09_Evaluation_of_core_data_b_GECO	pdf	5.69
210_0_Completion_Report	pdf	4.28
210_10_Geological_invest_of_cores_vol-1_by_SHELL	pdf	17.20
210_11_Geological_invest_of_cores_vol-2_by_SHELL	pdf	13.11
210_12_Geological_invest_of_cores_vol-3_by SHELL	pdf	75.61
210_13_Palynofacies_Jurassic_investigation_by SHELL	pdf	7.24
210_14_Special_ core_analysis_study_by_CORELAB	pdf	2.17
210_15_Special_core_analysis_by_CORELAB	pdf	1.85
210_16_Special_core_description_by_SHELL	pdf	2.09
210_17_Special_core_description_encl_1	pdf	0.15
210_18_Special_core_description_encl_2	pdf	0.15
210_19_Special_core_description_encl_3	pdf	0.14
210_20_Special_core_description_encl_4	pdf	0.16
210_21_Special_core_description_encl_5	pdf	0.15
210_22_Special_core_description_encl_6	pdf	0.12
210_23_Special_core_description_encl_7	pdf	0.15
210_24_Reservoir_fluid_study_Supplementary_Report_by_CORELAB	pdf	0.28
210_25_Well_test_report_by_STATOIL	pdf	1.40
210_26_Well_testing_rep_No_84-2301-10_by_FLOPETROL	pdf	17.02
210_27_Well_testing_rep_No_81-230-23_by_FLOPETROL	pdf	8.22
210_28_Well_testing_rep_No_81-2301-23_by_FLOPETROL	pdf	18.40
210_29_Bottom_ hole_pressure_calc_by_FLOPETROL	pdf	1.78
210_30_Final_report_Rock_Mineral_Analysis_GECO	pdf	0.16
210_31_High_acc_pres_temp_measure_by_FLOPETROL	pdf	1.10
210_32_Notes_on_oil_zone_test_by_SHELL	pdf	0.89
210_33_Pressure_survey_report_Run_1_by_Sperry	pdf	2.14
210_34_Pressure_survey_report_Run_2_by_Sperry	pdf	0.91
210_35_Pressure_survey_report_by_Sperry	pdf	1.09
210_36_SDP_Bottom_Hole_Press_ELS_84_24_by_Flopetrol	pdf	5.83
210_37_SDP_Bottom_Hole_Press_ELS_84_25_by_FLOPETROL	pdf	6.03
210_38_SDP_Bottom_Hole_Press_ELS_84_27_by_Flopetrol	pdf	1.21
210_39_SDP_Bottom_Hole_Press_ELS_84_28_by_Flopetrol	pdf	1.13
210_40_Source_rock_evaluation_by_SHELL	pdf	0.42
210_41_Source_rock_evaluation_encl_1	pdf	0.05
210_42_Geochem_analysis_of_crude_oil_by_SHELL	pdf	0.58
210_43_One_well_study_by_STATOIL	pdf	1.66
210_44_One_well_study_encl_1	pdf	0.81
210_45_Partial_Reservoir_Fluid_Study_by_Corelab	pdf	0.20
210_46_Particle_size_analysis_by_Anchor	pdf	0.42
210_47_Quick_look_evaluation_by_STATOIL	pdf	0.67
210_48_Quick_look_evaluation_encl_1	pdf	0.14
210_49_Quick_look_evaluation_encl_2	pdf	0.14
210_50_Quick_look_evaluation_encl_3	pdf	0.14
210_51_Quick_look_evaluation_encl_4	pdf	0.14
210_52_Reservoir_Fluid_Study_by_Corelab	pdf	0.80
210_53_Reservoir_Fluid_Study_by_Corelab	pdf	0.81
210_54_Rock_mineral_analysis_by_ Geco	pdf	0.11
210_55_Exploration_drilling_proposal_by_Shell	pdf	0.54
210_56_Exploration_drilling proposal_encl_1	pdf	0.76
210_57_Exploration_drilling_proposal_encl_2	pdf	0.21
210_58_Exploration_drilling_proposal_encl_3	pdf	0.39
210_59_Exploration_drilling_proposal_encl_4	pdf	10.45
210_60_Exploration_ drilling_proposal_encl_5	pdf	12.59
210_61_Exploration_drilling_proposal_encl_6	pdf	21.53
210_62_Exploration_drilling_proposal_encl_7	pdf	20.70
210_63_Exploration_drilling_proposal_encl_8	pdf	0.33

Drill stem tests (DST)

Drill stem tests (DST)
Test number	From depth MD [m]	To depth MD [m]	Choke size [mm]
1.0	1582	1588	0.0

Drill stem tests (DST)
Test number	Final shut-in pressure [MPa]	Final flow pressure [MPa]	Bottom hole pressure [MPa]	Downhole temperature [°C]
1.0

Drill stem tests (DST)
Test number	Oil [Sm3/day]	Gas [Sm3/day]	Oil density [g/cm3]	Gas grav. rel.air	GOR [m3/m3]
1.0

Logs

Logs
Log type	Log top depth [m]	Log bottom depth [m]
CBL VDL GR	362	1465
CBL VDL GR	810	1798
DLL MSFL GR	1468	1804
FDC CNL CAL GR	439	821
FDC CNL CAL GR	807	1467
FDC CNL CAL GR	1468	1805
FDC CNL CAL GR	1800	2527
HDT	1468	1805
HDT	1800	2524
HDT.2	1468	1805
HDT.2	1800	2522
ISF BHC GR SP	363	820
ISF BHC GR SP	630	1468
ISF BHC GR SP	1468	1805
ISF BHC GR SP	1800	2526
LDT GR	1468	1806
LSS GR	1468	1805
RFT	1468	1805
TMP	300	1261
TMP	330	1630
TMP	1390	1630
VELOCITY	363	2526

Casing and leak–off tests

Casing and leak–off tests
Casing type	Casing diam. [inch]	Casing depth [m]	Hole diam. [inch]	Hole depth [m]	LOT/FIT mud eqv. [g/cm3]	Formation test type
CONDUCTOR	30	443.0	36	446.0	0.00	LOT
CONDUCTOR	30	446.0	36	446.0	0.00	LOT
SURF.COND.	20	810.0	26	820.0	1.55	LOT
INTERM.	13 3/8	1470.0	17 1/2	1480.0	1.60	LOT
INTERM.	9 5/8	1801.0	12 1/4	1812.0	1.69	LOT
OPEN HOLE		2532.0	8 1/2	2532.0	0.00	LOT

Drilling mud

Drilling mud
Depth MD [m]	Mud weight [g/cm3]	Visc. [mPa.s]	Mud type
414	1.03		seawater
473	1.05	36.0	seawater
788	1.20	75.0	waterbased
1270	1.21	54.0	waterbased
1448	1.25	55.0	waterbased
1806	1.15	50.0	waterbased

Thin sections at the Norwegian Offshore Directorate

Thin sections at the Norwegian Offshore Directorate
Depth	Unit
1540.00	[m ]
1545.00	[m ]
1556.00	[m ]
1559.00	[m ]
1567.00	[m ]
1570.00	[m ]
1574.00	[m ]
1601.00	[m ]
1605.00	[m ]
1608.00	[m ]
1618.00	[m ]
1621.00	[m ]
1626.00	[m ]

Pressure plots

Pressure plots
The pore pressure data is sourced from well logs if no other source is specified. In some wells where pore pressure logs do not exist, information from Drill stem tests and kicks have been used. The data has been reported to the NPD, and further processed and quality controlled by IHS Markit.

Pressure plots
Document name	Document format	Document size [MB]
210_Formation_pressure_(Formasjonstrykk)	pdf	0.22

31/2-5