- General information
Wellbore name
25/8-16 S
Type
EXPLORATION
Purpose
WILDCAT
Status
P&A
Press release
Factmaps in new window
Main area
NORTH SEA
Discovery
Well name
25/8-16
Seismic location
ES9403.inline 1433 & xline2484
Drilled in production licence
Drilling operator
ExxonMobil Exploration and Production Norway AS
Drill permit
1237-L
Drilling facility
Drilling days
34
Entered date
10.04.2009
Completed date
13.05.2009
Release date
13.05.2011
Publication date
13.05.2011
Purpose - planned
WILDCAT
Reentry
NO
Content
OIL
Discovery wellbore
YES
1st level with HC, age
PALEOCENE
1st level with HC, formation
HEIMDAL FM
Kelly bushing elevation [m]
25.0
Water depth [m]
126.0
Total depth (MD) [m RKB]
2550.0
Final vertical depth (TVD) [m RKB]
2132.0
Maximum inclination [°]
61.5
Bottom hole temperature [°C]
84
Oldest penetrated age
EARLY JURASSIC
Oldest penetrated formation
STATFJORD GP
Geodetic datum
ED50
NS degrees
59° 24' 56.25'' N
EW degrees
2° 29' 2.34'' E
NS UTM [m]
6586599.87
EW UTM [m]
470710.44
UTM zone
31
NPDID wellbore
6082
 
 
- Wellbore history
General
Well 25/8-16 S is located on the Utsira High in the southern part of the Viking Graben in the North Sea. It was drilled to test the hydrocarbon and reservoir potential in two prospects. The man target was the Eitri prospect in the paleocene Ty Formation, and the second target was the Phi prospect in the Statfjord Formation. Depending on findings in the Ty and Statfjord reservoir sections, it was an option to drill one or two sidetracks. For dry hole cases in Ty and Statfjord reservoir sections, no sidetracks should be drilled.
Operations and results
Wildcat well 25/8-16 S was spudded with the semi-submersible installation Bredford Dolphin on 10 April 2009 and drilled to TD at 2550 m (2132 m TVD) in the Early Jurassic Statfjord Formation . The well was drilled vertical down to 1100 m, and then deviated towards the south. The well was drilled with Seawater/spud mud down to 1935 m and with XP-07 oil based mud from 1035 m to TD.
A 3 m thick oil column was discovered in the Heimdal Formation, in the 12 1/4" section. The oil - water contact was not found. The Heimdal Formation was not one of the targets for the well, and was not prognosed as it was believed to pinch out down flanks of the well. No signs of hydrocarbons were found in the main target Ty Formation, or in the secondary target of Statfjord Formation. No oil shows above the oil based mud were recorded in the well.
No cores were cut in the well. MDT fluid samples were taken with dual packer through perforation in casing at 2232.65 m (1972.65 m TVD) in the Heimdal Formation. When the MDT run was performed, the Heimdal Formation had been behind casing for 8 days, and there had been no circulation for about 100 hours. After 48 hours and pumping of 1769 litres the measured temperature was 79.5 deg C. This temperature is regarded as highly representative for the formation. The samples consisted of oil with a GOR ranging from 136.3 to 149.6 Sm3/Sm3.
Based on the findings in 25/8-16 S, it was decided to drill a side track (25/8-16A) to appraise the discovery made in the Heimdal Formation.
The well bore was permanently abandoned on 13 May 2009 as an oil discovery.
Testing
No drill stem test was performed.
 
 
- Cuttings at the NPD
Cutting sample, top depth [m]
Cutting samples, bottom depth [m]
1040.00
2550.00
Cuttings available for sampling?
YES
 
 
- Lithostratigraphy
 
 
- Logs
Log type
Log top depth [m]
Log bottom depth [m]
GR CCL PERF
2232
2232
IBC CBL GR CCL
1900
2290
MDT DP
2232
2232
MWD LWD - DIR
151
220
MWD LWD - DIR DGR EWR PWD
220
1036
MWD LWD - DIR DGR EWR PWD
1036
2550
MWD LWD - DIR DGR PWD
220
1036
 
 
- Casing and leak-off tests
Casing type
Casing diam.
[inch]
Casing depth
[m]
Hole diam.
[inch]
Hole depth
[m]
LOT mud eqv.
[g/cm3]
Formation test type
CONDUCTOR
30
216.0
36
216.0
0.00
LOT
SURF.COND.
13 3/8
1030.0
17 1/2
1039.0
1.82
LOT
INTERM.
9 5/8
2353.0
12 1/4
2370.0
1.57
LOT
OPEN HOLE
2550.0
8 1/2
2550.0
0.00
LOT
 
 
 
- Drilling mud
Depth MD [m]
Mud weight [g/cm3]
Visc. [mPa.s]
Yield point [Pa]
Mud type
Date measured
179
1.06
  
Spud Mud
 
958
1.06
  
Spud Mud
 
1021
1.47
21.0
 
XP-07
 
1035
1.25
18.0
 
Spud Mud
 
1159
1.50
21.0
 
XP-07
 
2346
1.50
21.0
 
XP-07
 
2370
1.50
20.0
 
XP-07
 
2551
1.39
20.0
 
XP-07