Wellbore: 2/8-8 - 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.	2/8-8
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
Multilateral Indicator telling if the parent well is multilateral, meaning it has more than one branch radiating from the main borehole. Example of legal values: YES, NO. See also Norwegian Offshore Directorate guidelines for designation of wells and wellbores.	NO
Factmaps in new window	link
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.	VALHALL
Discovery Name of the discovery the wellbore is related to.	2/8-6 Valhall
Well name Official name of the parent well for the wellbore based on Norwegian Offshore Directorate guidelines for designation of wells and wellbores.	2/8-8
Production licence Official designation of the production licence the wellbore was drilled or planned to be drilled from ( well head posistion).	006
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.	Amoco Norway Oil Company
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.	143-L
Drilling facility Norwegian Offshore Directorate's name of the facility which the wellbore was drilled from.	DEEPSEA SAGA
Drilling days Number of days from wellbore entry to wellbore completion.	127
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,	10.11.1975
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.	15.03.1976
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.	15.03.1978
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.	16.10.2012
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
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 CRETACEOUS
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.	TOR 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.	LATE CRETACEOUS
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.	HOD 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.	70.0
Total depth (MD) [m RKB] Total measured length of wellbore from kelly bushing to total depth (driller's depth).	2667.0
Bottom hole temperature [°C] Estimated temperature at final total depth of the wellbore. Shown only for released wells. See discription.	77
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.	EARLY CRETACEOUS
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.	RØDBY FM
Geodetic datum Reference system for coordinates. Example of legal values: ED50.	ED50
NS degrees Geographic coordinate of the wellhead, north-south degrees.	56° 16' 49.81'' N
EW degrees Geographic coordinate of the wellhead, east-west degrees.	3° 24' 12.71'' E
NS UTM [m] Universal Transverse Mercator coordinate of the wellhead, north-south.	6237510.96
EW UTM [m] Universal Transverse Mercator coordinate of the wellhead, east-west.	524985.88
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.	278

Wellbore history

General

Well 2/8-8 was drilled to appraise the Valhall discovery in the southern North Sea. The well is reference well for the Hod Formation.

Operations and results

Appraisal well 2/8-8 was spudded with the semi-submersible installation Deepsea Saga on 10 November 1975 and drilled to TD at 2667 m in the Early Cretaceous Rødby Formation. While running the 13 3/8-inch casing, returns (125 barrels) were lost while pumping plug. While cementing the 9 5/8-inch casing, the cement slurry was not properly displaced, and the casing was cemented back on the inside to 1022 m. Three days were lost due to this in drilling out the cement. Otherwise the well was drilled without significant problems. The well was drilled with sea water and hi-vis mud down to 169 m, with sea water/gel mud from 169 m to 402 m, and with lignosulphonate/gypsum mud from 402 m to TD.

Oil shows were recorded at several levels above the chalk reservoir: 1320 - 1329 m had fair shows on siltstones; 1390 to 1426 m had poor shows in shales and limestone; 1512 to 1676 m had oil staining with fluorescence and cut in shales; and 2050 to 2400 m had poor to fair shows in thin stringers of limestone and dolomite. Top of the chalk reservoir, Tor Formation, was encountered at 2447. It was oil bearing and had shows down to 2591 m. No shows were recorded below 2591 m.

At total of 47.7 m core was recovered in 14 cores from 2450 to 2600.9 m. The overall recovery was 39 %. No wire line fluid samples were taken.

The well was permanently abandoned on 15 March 1978 as an oil appraisal well.

Testing

Tests were conducted over five intervals. Sand-water hydraulic fracture treatments were conducted on Tests 2, 3 and 4.

Test 1 tested the interval 2585 to 2595 m towards the base of the Hod Formation. The well was opened for flow during 34.6 hrs. 3.8 m3 cushion water and unmeasured oil and gas were produced to surface while 8 m3 oil cut water was reversed out of the test string.

Test 2 tested the interval 2556 to 2567.9 m in the Hod Formation. The test produced 455 Sm3 oil /day through a 48/64" choke. The GOR was 123 Sm3/Sm3.

Test 3 tested the interval 2507 to 2514.9 m in the Hod Formation. The test produced on average180 Sm3 oil /day. The GOR was 139 Sm3/Sm3 and the oil gravity was 38.1 deg API. The test also produced solids, plugging the chokes and causing unstable flow.

Test 4 tested the interval 2488 to 2492.7 m in the lower Tor Formation. The test produced 745 Sm3 oil /day through a 32/64" choke. The GOR was 218 Sm3/Sm3.

Test 5 tested the interval 2460 to 2464.6 m in the Tor Formation. The test produced 1222 Sm3 oil /day with open choke. The GOR was 199 Sm3/Sm3 and the oil gravity was 35.2 deg API.

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]
168.86	2667.00

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	8038.0	8083.0	[ft ]
2	8083.0	8143.0	[ft ]
3	8143.0	8158.0	[ft ]
4	8160.0	8188.0	[ft ]
5	8188.0	8196.6	[ft ]
6	8218.0	8226.0	[ft ]
7	8246.0	8251.0	[ft ]
8	8276.0	8292.0	[ft ]
9	8314.0	8345.0	[ft ]
10	8345.0	8354.0	[ft ]
11	8375.0	8390.0	[ft ]
12	8393.0	8401.0	[ft ]
13	8417.0	8433.0	[ft ]
14	8515.0	8533.0	[ft ]

Cores at the Norwegian Offshore Directorate
Total core sample length [m]	86.1

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

Core photos

Core photos

8160-8166ft	8160-8166ft	8166-8172ft	8166-8172ft	8172-8177ft

8172-8177ft	8177-8183ft	8177-8183ft	8183-8188ft	8183-8186ft

8188-8190ft	8188-8190ft	8190-8196ft	8190-8196ft	8218-8224ft

8218-8224ft	8224-8226ft	8224-8226ft	8246-8251ft	8246-8251ft

8276-8280ft	8276-8280ft	8314-8320ft	8314-8320ft	8320-8326ft

8320-8326ft	8326-8332ft	8326-8332ft	8332-8338ft	8332-8338ft

8338-8344ft	8338-8344ft	8338-8345ft	8344-8345ft	8345-8351ft

8345-8351ft	8351-8354ft	8351-8354ft	8375-8381ft	8375-8381ft

8381-8387ft	8381-8387ft	8387-8390ft	8387-8390ft	8393-8399ft

8393-8399ft	8399-8401ft	8399-8401ft	8417-8423ft	8417-8423ft

8423-8429ft	8423-8429ft	8429-8433ft	8429-8433ft	8515-8521ft

8515-8521ft	8521-8527ft	8521-8527ft	8527-8533ft	8527-8533ft

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	169.0	36	169.0	0.00	LOT
SURF.COND.	20	380.0	26	388.0	1.31	LOT
INTERM.	13 3/8	1285.0	17 1/2	1295.0	2.11	LOT
INTERM.	9 5/8	2411.0	12 1/4	2419.0	1.97	LOT
LINER	7	2659.0	8 1/2	2667.0	0.00	LOT

Drill stem tests (DST)

Drill stem tests (DST)
Test number	From depth MD [m]	To depth MD [m]	Choke size [mm]
1.0	2585	2595	0.0
2.0	2556	2568	19.0
3.0	2507	2515	0.0
4.0	2488	2493	12.5
5.0	2460	2465	25.4

Drill stem tests (DST)
Test number	Final shut-in pressure [MPa]	Final flow pressure [MPa]
1.0
2.0	43.000	32.000
3.0	44.600	23.300
4.0
5.0	44.000	36.000

Drill stem tests (DST)
Test number	Oil [Sm3/day]	Oil density [g/cm3]	GOR [m3/m3]
1.0
2.0	455		690
3.0	179	0.830	780
4.0	745		1225
5.0	1222	0.850	1118

Logs

Logs
Log type	Log top depth [m]	Log bottom depth [m]
CBL	100	610
CBL	2095	2400
CBL VDL	2252	2637
CBL VDL GR CAL	2416	2667
DIP	2412	2666
DLL MSFL GR SP CAL	2413	2660
FDC CNL GR CAL	2413	2668
FDL CNL GR CAL	100	2426
GR SON CAL	1285	2423
GR SON CAL	2413	2664
IES SP	1287	2426
IES SP	2413	2668
VELOCITY	1285	2423
VELOCITY	2413	2664

Lithostratigraphy

Lithostratigraphy
Top depth [mMD RKB]	Lithostrat. unit
95	NORDLAND GP
1536	HORDALAND GP
2409	ROGALAND GP
2409	BALDER FM
2419	SELE FM
2429	LISTA FM
2447	SHETLAND GP
2447	TOR FM
2494	HOD FM
2601	BLODØKS FM
2603	HIDRA FM
2619	CROMER KNOLL GP
2619	RØDBY FM

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]
278_2_8_8_Completion_log	pdf	1.29
278_2_8_8_Completion_report	pdf	31.99

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]
278_01_WDSS_General_Information	pdf	0.29

Drilling mud

Drilling mud
Depth MD [m]	Mud weight [g/cm3]	Mud type
380	1.11	waterbased
1284	1.23	waterbased
2410	1.80	waterbased
2445	1.85	waterbased