Wellbore: 7/12-6 - 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.	7/12-6
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.	P&A
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.	ULA
Discovery Name of the discovery the wellbore is related to.	7/12-2 Ula
Well name Official name of the parent well for the wellbore based on Norwegian Offshore Directorate guidelines for designation of wells and wellbores.	7/12-6
Seismic location Position of spud location on seismic survey lines. SP: shotpoint.	CN7 - 111 SP: 584.
Production licence Official designation of the production licence the wellbore was drilled or planned to be drilled from ( well head posistion).	019
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.	BP Norway Limited U.A.
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.	282-L
Drilling facility Norwegian Offshore Directorate's name of the facility which the wellbore was drilled from.	SEDCO 707
Drilling days Number of days from wellbore entry to wellbore completion.	106
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,	10.04.1981
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.	24.07.1981
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.	24.07.1983
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.	01.01.2012
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.	APPRAISAL
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
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.	ULA FM
2nd level with HC, age Age of lithostratigraphic unit, 2nd level, where hydrocarbons were encountered. Examples of legal values: CRETACEOUS, EARLY CRETACEOUS, LATE JURASSIC, EOCENE.	TRIASSIC
2nd level with HC, formation Name of lithostartigraphic unit, 2nd 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.	SKAGERRAK FM
Kelly bushing elevation [m] Elevation of the rotary kelly bushing (RKB) above mean sea level.	25.0
Water depth [m] Depth in metres betweem mean sea level and sea floor.	69.0
Total depth (MD) [m RKB] Total measured length of wellbore from kelly bushing to total depth (driller's depth).	3700.0
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).	3699.0
Maximum inclination [°] Maximum deviation, in degrees, from a vertical well path.Shown only for released wells.	2.5
Bottom hole temperature [°C] Estimated temperature at final total depth of the wellbore. Shown only for released wells. See discription.	153
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.	SKAGERRAK FM
Geodetic datum Reference system for coordinates. Example of legal values: ED50.	ED50
NS degrees Geographic coordinate of the wellhead, north-south degrees.	57° 7' 16.85'' N
EW degrees Geographic coordinate of the wellhead, east-west degrees.	2° 50' 4.14'' E
NS UTM [m] Universal Transverse Mercator coordinate of the wellhead, north-south.	6331048.10
EW UTM [m] Universal Transverse Mercator coordinate of the wellhead, east-west.	489977.47
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.	281

Well 7/12-6 was drilled as an appraisal well on the Ula Field in the southern North Sea. The objective was to determine sand distribution in northern part of the Ula field, and production and injection properties of reservoir and aquifer.

Operations and results

Appraisal well 7/12-6 was spudded with the semi-submersible installation Sedco 707 on 10 April 1981 and drilled to TD at 3700 m in the Triassic Skagerrak Formation. Some hole problems and excessive cavings due to underbalanced drilling occurred in the 12 1/4" section between 2633 and 3353 m, otherwise the well was drilled without significant technical problems or delay. The well was drilled with gel/seawater and fluid loss additives down to 480 m and with gypsum/lignosulphonate and fluid loss additives from 480 m to TD.

The Ula Formation sandstones were penetrated at 3406 m. The sandstones were 115 m thick, very fine to fine grained with porosities from 10 to 25% and permabilities from 1 to 2000 mD. The reservoir was oil bearing throughout, no OWC was established. An unexpected Triassic reservoir of good quality was found below the Ula Formation. The well drilled 179 m into it without reaching the OWC. The reservoir consisted of various types of micaceous sandstones with porosities from 4 to 23% and permabilities from 0.03 to 2600 mD. The first hydrocarbon indication was recorded as a weak oil show at 2440 in siltstone. Further shows were recorded in the Late Cretaceous between 3010 m and 3060 m, however the logs did not indicate any significant mobile hydrocarbon. Hydrocarbon shows were recorded throughout the Upper Jurassic Ula Formation between 3407 m and 3521 m. Patchy shows were recorded in the Triassic interval between 3521 m and TD.

A total of 240 m core was cut in 9 cores over the interval 3407.7 to 3647.17 m in the Ula and Skagerrak formations. RFT fluid samples were taken at 3437 m (oil), 3533.5 m (mud filtrate), and at 3530.5 m (mud filtrate).

The well was permanently abandoned on 24 July 1981 as an oil appraisal well.

Testing

Both reservoirs were tested.

DST 1C in the Triassic Skagerrak Formation reservoir (3543 - 3612 m) flowed 160 Sm3 oil and 5720 Sm3 gas through a 12/64" choke. The GOR was 36 Sm3/Sm3. The oil density was 0.810 g/cm3 and the separator gas gravity was 0.806 (air = 1). The bottom hole temperature measured at 3531 m, was 149.4 deg C.

DST 2 in the Ula Formation sandstone reservoir (3434 - 3511 m) flowed 1269 Sm3 oil and 84526 Sm3 gas through a 32/64" choke. The GOR was 67 Sm3/Sm3. The oil density was 0.842 g/cm3 and the separator gas gravity was 0.840 (air = 1). The bottom hole temperature measured at 3425 m, was 143.3 deg C.

DST 2 was followed by an injection test. The maximum injection rate was 1407 Sm3/day at a wellhead injection pressure of 3100 to 3200 psi. As no OWC was seen the no injection test could be performed in the aquifer.

Cuttings at the Norwegian Offshore Directorate

Cuttings at the Norwegian Offshore Directorate
Cuttings available for sampling?	NO

Cuttings at the Norwegian Offshore Directorate
Cutting sample, top depth [m]	Cutting samples, bottom depth [m]
180.00	3632.00

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	3406.7	3434.3	[m ]
2	3434.3	3461.3	[m ]
3	3461.6	3488.6	[m ]
4	3488.6	3515.5	[m ]
5	3515.5	3542.8	[m ]
6	3542.8	3569.8	[m ]
7	3569.8	3596.8	[m ]
8	3596.8	3624.3	[m ]
9	3624.3	3647.2	[m ]

Cores at the Norwegian Offshore Directorate
Total core sample length [m]	240.1

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

Core photos

Core photos

3406-3409m	3409-3412m	3412-3414m	3414-3417m	3417-3420m

3420-3422m	3422-3425m	3425-3428m	3428-3431m	3431-3433m

3433-3434m	3434-3437m	3437-3439m	3439-3442m	3442-3445m

3445-3447m	3447-3450m	3450-3453m	3453-3455m	3455-3458m

3458-3461m	3461-3464m	3464-3467m	3467-3469m	3469-3472m

3472-3475m	3475-3477m	3477-3480m	3480-3483m	3483-3485m

3485-3488m	3488-3491m	3491-3494m	3494-3496m	3496-3499m

3499-3502m	3502-3504m	3504-3507m	3507-3510m	3510-3512m

3512-3515m	3515-3518m	3518-3520m	3520-3523m	3523-3526m

3526-3528m	3528-3531m	3531-3534m	3534-3537m	3537-3539m

3539-3542m	3542-3543m	3543-3545m	3545-3548m	3548-3550m

3550-3553m	3553-3556m	3556-3558m	3558-3561m	3561-3564m

3564-3567m	3567-3569m	3569-3572m	3572-3575m	3575-3577m

3577-3580m	3580-3583m	3583-3585m	3585-3588m	3588-3591m

3591-3594m	3594-3596m	3596-3599m	3599-3602m	3602-3604m

3604-3607m	3607-3610m	3610-3612m	3612-3615m	3615-3618m

3618-3621m	3621-3623m	3623-3624m	3624-3626m	3626-3629m

3629-3632m	3632-3635m	3635-3637m	3637-3640m	3640-3643m

3643-3645m	3645-3646m

Oil samples at the Norwegian Offshore Directorate

Oil samples at the Norwegian Offshore Directorate
Test type	Bottle number	Top depth MD [m]	Bottom depth MD [m]	Fluid type	Test time	Samples available
DST	TEST2	0.00	3511.00		16.07.1981 - 00:00	YES
DST		0.00	0.00		29.06.1983 - 00:00	YES

Lithostratigraphy

Lithostratigraphy
Top depth [mMD RKB]	Lithostrat. unit
94	NORDLAND GP
1672	HORDALAND GP
2539	ROGALAND GP
2539	BALDER FM
2564	SELE FM
2605	LISTA FM
2661	VIDAR FM
2702	LISTA FM
2710	VÅLE FM
2730	SHETLAND GP
2730	EKOFISK FM
2810	TOR FM
3002	HOD FM
3071	BLODØKS FM
3085	HIDRA FM
3092	CROMER KNOLL GP
3092	RØDBY FM
3292	TYNE GP
3292	MANDAL FM
3332	FARSUND FM
3406	ULA FM
3521	NO GROUP DEFINED
3521	SKAGERRAK FM

Geochemical information

Geochemical information
Document name	Document format	Document size [MB]
281_1	pdf	1.21
281_2	pdf	5.39
281_3	pdf	0.35

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]
281_01_WDSS_General_Information	pdf	0.11
281_02_WDSS_completion_log	pdf	0.27

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]
281_7_12_6_Completionh_report_I	pdf	18.37
281_7_12_6_Completion_log	pdf	2.34
281_7_12_6_Completion_report_II	pdf	29.48
281_7_12_6_Drill_stem_testing_field_report	pdf	27.74
281_7_12_6_Evaluation_of_core_data	pdf	0.30
281_7_12_6_Formation_Evaluation_Study_of_Ula_Field	pdf	37.34
281_7_12_6_Formation_testing_service_report_DST_NO_1C	pdf	5.33
281_7_12_6_Formation_testing_service_report_DST_NO_2	pdf	3.87
281_7_12_6_Geological_ Evaluation_of_the_Triassic_oil_Discovery	pdf	3.95
281_7_12_6_Geological_Evaluation_of_the_Triassic_oil_Discovery	pdf	3.98
281_7_12_6_Injection_testing_measurement_DST_NO_2	pdf	2.60
281_7_12_6_Petroleum_Engineering_Completion_Report	pdf	29.48
281_7_12_6_Pressure_survey_report_DST_NO_2	pdf	4.31
281_7_12_6_Reservoir_fluid_study_DST_NO_1	pdf	1.66
281_7_12_6_Reservoir_fluid_study_DST_NO_2	pdf	1.81
281_7_12_6_Sampling_and_gas_analysis	pdf	0.68
281_7_12_6_Sedimentology_and_Diagenesis_of_Triassic_Cored	pdf	45.04
281_7_12_6_Special_core_analysis_study_UKSCAL-311-811891	pdf	13.49
281_7_12_6_Special_core_analysis_study_UKSCAL-311-811893	pdf	3.88
281_7_12_6_Special_Fluid_Study_DST_NO_2	pdf	0.99
281_7_12_6_Specia_core_analysis_study_UKSAL-311-811892	pdf	11.31
281_7_12_6_Temperature_Survey_Report	pdf	2.96
281_7_12_6_Testing_procedures	pdf	2.67
281_7_12_6_The_sedimentology_and_reservoir_geology	pdf	207.05
281_7_12_6_Well_testing_Report_annexes	pdf	9.83
281_7_12_6_Well_testing_Report_DST_NO.1C	pdf	10.26
281_7_12_6_Well_testing_Report_DST_NO.2	pdf	11.87

Drill stem tests (DST)

Drill stem tests (DST)
Test number	From depth MD [m]	To depth MD [m]	Choke size [mm]
1.0	3544	3612	4.7
2.0	3434	3511	12.7

Drill stem tests (DST)
Test number	Final shut-in pressure [MPa]	Final flow pressure [MPa]	Bottom hole pressure [MPa]	Downhole temperature [°C]
1.0				149
2.0				143

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	160	5720	0.816	0.806	36
2.0	1270	84526	0.842	0.840	66

Logs

Logs
Log type	Log top depth [m]	Log bottom depth [m]
CBL	3125	3632
CCL	160	195
CCL	3100	3508
CCL	3300	3525
CCL	3300	3390
DLL MSFL	3337	3703
FDC CNL CAL GR	3337	3704
HDT SL	3337	3703
ISF BHCS GR MSFL CAL	465	1692
ISF BHCS GR MSFL CAL	1684	3351
ISF BHCS GR SP	93	477
ISF BHCS SP GR	3337	3702
RFT GR	3415	3670
RFT GR	3416	3570
VELOCITY	200	3650

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	167.0	36	172.0	0.00	LOT
SURF.COND.	18 5/8	465.0	17 1/2	480.0	1.88	LOT
INTERM.	13 3/8	1684.0	17 1/2	1696.0	1.83	LOT
INTERM.	9 5/8	3337.0	12 1/4	3350.0	1.97	LOT
LINER	7	3688.0	8 1/2	3700.0	0.00	LOT

Drilling mud

Drilling mud
Depth MD [m]	Mud weight [g/cm3]	Visc. [mPa.s]	Mud type
390	1.14	85.0	waterbased
1680	1.30	58.0	waterbased
1990	1.42	48.0	waterbased
2630	1.50	59.0	waterbased
3390	1.50	51.0	waterbased

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]
281_Formation_pressure_(Formasjonstrykk)	pdf	0.22

7/12-6