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Exploration wellbore: 25/8-10 S

General information

NPDID wellbore:	3062
Well name:	25/8-10
Drilling operator name:	Esso Exploration and Production Norway A/S
Geodetic datum:	ED50
Coordinates:	59° 16` 22.69`` N	2° 32` 06.40`` E
UTM coordinates:	6570692.44 N	473501.58 E
UTM zone:	31
Drilled in production licence:	027
Area:	NORTH SEA
Discovery:	25/8-10 S RINGHORNE
Field:	BALDER
Drill permit:	883-L
Drilling facility:	DEEPSEA TRYM
Drilling days:	37
Wellbore entry date:	29.04.1997
Wellbore completion date:	05.06.1997
Original wellbore purpose:	WILDCAT
Wellbore purpose:	WILDCAT
Wellbore status:	P&A
Wellbore contents:	OIL/GAS
Discovery wellbore:	YES
Formation/age with hydrocarbons 1:	HERMOD FM / PALEOCENE
Formation/age with hydrocarbons 2:	HEIMDAL FM / PALEOCENE
Seismic location:	ESD96-3 & SP 577
Kelly bushing elevation (KB) [m]:	25
Water depth [m]:	129
Total Depth (MD) [m]:	1890
Final vertical depth (TVD) [m]:	1884
Max inclination [°]:	10.40
Bottom hole temperature [°C]:	83
Oldest penetrated age:	PALEOCENE
Oldest penetrated formation:	EKOFISK FM
Note: All depths, except the water depth, are relative to kelly bushing (RKB)

Wellbore history

General

Well 25/8-10 S is located north of the Grane Field. The well was drilled and tested to obtain representative fluid samples, production characteristics, and reservoir permeabilities in the Forseti Prospect in the Hermod - Middle Heimdal formation.

Operations and results

Exploration well 25/8-10 S was spudded with semi-submersible drilling installation "Deepsea Trym" on 29 April 1997 and drilled to TD at 1749.5 m in the Late Paleocene Lista Formation. The original 25/8-10 S well was drilled with a slightly deviated profile (+/- 6 degree maximum angle) to a depth of 1749 m MD RKB. Due to a mechanical problem, which occurred after coring at 1722-1749 m, the well was plugged back and a technical sidetrack (25/8-10S T2) was kicked off at 1076 m and drilled to the original geologic objective at a total depth of 1890 m in the Early Paleocene Ekofisk Formation. Well 25/8-10 S was drilled with seawater and bentonite sweeps down to 1091 m and with oil based "Ancovert" mud from 1091 m to TD. The technical sidetrack 25/810 S T2 was drilled with oil based with "Ancovert" mud. The sidetrack penetrated 18 m (net pay) of oil filled sand in the Hermod - Middle Heimdal formation with an OWC, based on logs, at 1755.5 m TVD SS. The pay zone consisted of three sand intervals. One core was cut in the 25/8-10 S wellbore in the interval 1722 m to 1749.65 m (Sele, Hermod, and Lista Formations). A second core was cut in the 25/8-10 S T2 sidetrack in the interval 1749 m to 1786 m. (Lista and Heimdal Formations). After wire line logging the 25/8-10S T2 well a drill stem test of the upper sand interval, in the Hermod Formation, was performed. Fluid samples were taken during the DST. The well was permanently abandoned on 5 June 1997 as an oil and gas discovery, named the 25/8-10 S Ringhorne Discovery.

Testing

The interval from 1727.0 m to 1740.5 m (1698.6 - 1711.9 m TVD SS) in the Hermod Formation was perforated. The test showed an unconsolidated reservoir with high porosity. The GOR at rate 445 Sm3 fluid/day increased roughly from 45 Sm3/Sm3 to 90 Sm3/Sm3 as the wellhead pressure increased from 600 to 800 psia. This was considered consistent with the presence of a gas cap.

Cuttings available at the NPD

Interval [m]: 1100.00 - 1890.00

Cores available at the NPD

Core length [m]: 64.65

Core number	Interval
1	1722.00-1749.65
2	1749.00-1786.00

Scanned core photos

1749-1754m	1754-1759m	1759-1764m	1764-1769m	1769-1774m
1774-1779m	1779-1784m	1784-1786m

Palynological slides available at the NPD

No palynological slides in this wellbore.

Oil samples available at the NPD

No oil samples available.

Casing and leak-off tests

Type	Casing diam. [inch]	Depth below KB [m]	Hole diam. [inch]	Hole depth below KB [m]
CONDUCTOR	30	227.0	36	228.0
SURF.COND.	13 3/8	1076.0	17 1/2	1091.0
OPEN HOLE		1890.0	8 1/2	1890.0

Mud

Depth MD [m]	Mud weight [g/cm³]	Visc. [MPa.s]	Mud type
227	1.03		SPUD MUD
890	1.32	31.0	OIL (REGULAR)
1000	1.06		SPUD MUD
1050	1.32	32.0	OIL (REGULAR)
1091	1.43	60.0	LO-TOX OBM
1150	1.32	28.0	LO-TOX OBM
1243	1.32	26.0	LO-TOX OBM
1517	1.32	28.0	LO-TOX OBM
1751	1.32	29.0	LO-TOX OBM
1786	1.32	30.0	LO-TOX OBM
1890	1.32	30.0	OIL (REGULAR)

Drill stem test (intervals and pressures)

Test no.	Test interval [m]	Choke size [mm]	Final shut in pressure [MPa]	Final flow pressure [MPa]	Bottom hole pressure [MPa]	Downhole temperature [°C]
1.0	1727 - 1740	14.4	4.000	4.000	4.000	0

Drill Stem Test (recovery)

Test no.	Oil [Sm³/day]	Gas [Sm³/day]	Oil grav. [g/cm³]	Gas grav. rel.air	GOR [m³/m³]
1.0	413	15	.900	.680	0

Available logs

Log type	Intervals logged [m]
MWD - GR RES DIR	228 - 1086
MWD - GR RES DIR	1076 - 1707

Lithostratigraphy

Top depth [m]	Litostratigraphic unit
154	NORDLAND GP
629	UTSIRA FM
692	NO FORMAL NAME
757	HORDALAND GP
757	SKADE FM
900	NO FORMAL NAME
910	SKADE FM
1100	NO FORMAL NAME
1645	ROGALAND GP
1645	BALDER FM
1708	SELE FM
1725	HERMOD FM
1741	LISTA FM
1761	HEIMDAL FM
1765	LISTA FM
1777	HEIMDAL FM
1827	SHETLAND GP
1827	EKOFISK FM

Composite log

Composite log (Format:PDF. Size: 0.275 Mb)
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Geochemical information available at the NPD

No geochemical data presently available. Regional geochemical studies which include data from this well may however be filed on a different well.

Documents reported by the licencees (period for duty of secrecy expired)

No documents presently available.