ZEUS PETROLEUM LIMITED
RELINQUISHMENT REPORT FOR P.1393;
BLOCKS 12/15, 13/11, 13/12 & 13/13
Licence:
P.1393
Blocks: 12/15, 13/11, 13/12 & 13/13
23rd Round Promote Licence
Operator:
Zeus Petroleum Ltd.
Work Programme Summary:
100%
Acquire and interpret 760km 2D seismic data. Construct a
tectonostratigraphic framework of the Jurassic in the
licensed area (Promote). Fulfilled.
Acquire 1700 km high resolution 2D seismic with pseudo
3D processing -equivalent to 300 km2 3D (Extension
period). Fulfilled (1849km full fold data acquired).
Contingent well: Test Jurassic & Cretaceous targets to a
depth of 3050m, contingent on;
1) Further analysis of the leads already identified to
demonstrate the presence of a competent trapping
mechanism (based on new seismic) and
2) The presence of any Direct Hydrocarbon Indicators on
the above leads (based on the new seismic).
Waived in view of absence of viable prospects in Blocks.
SYNOPSIS
Blocks 12/15, 13/11, 13/12, & 13/13 were awarded as Promote licence P 1393 to
Wimbledon Oil & Gas Ltd, as part of the 23rd round awards, in December 2005.
Wimbledon was subsequently purchased by Zeus in September 2006.
The blocks are located in a high risk, relatively under explored area of the Moray
Firth (Wick Basin) and prior to the current licence being taken up, were covered by a
loose grid of 2D seismic lines. The original application for the license was based on
the identification of a number of conceptual leads in the primary Upper Jurassic and
secondary Lower Cretaceous strata and Zeus latterly undertook to shoot a proprietary
high resolution 2D seismic survey in conjunction with pseudo 3D processing (See
Figure 1).
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The pseudo 3-D confirmed the particular difficulties in acquiring high quality data in
this part of the Moray Firth area of the North Sea, with data quality still not
comparable to that in other basins of the North Sea. Major differences between the
older 2-D data and the latest data therefore led to more significant reassessments of
plays developed on earlier data than might be expected in other areas of the North
Sea.
Fig 1:
The results of the interpretation of this pseudo 3D seismic data and integrated
examination of the geological well data have confirmed that many speculative leads
identified on the previous 2D data are not supported by the interpretation of the
recently acquired high resolution dataset and that there are no significant prospects
within the licence to drill a contingent well on (figure 2). Some prospectivity remains
in the Scapa sands but there is considerable doubt about the trapping mechanism for
this developing play and it must be deemed too high a risk. Overall therefore there
are no prospects of the requisite size, trap competence or risk. No direct hydrocarbon
indicators have been recognised.
DECC is free to publish this relinquishment report.
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ZEUS PETROLEUM LIMITED
WICK BASIN
WICK BASIN
Fig 2:
EXPLORATION ACTIVITIES
In order to fulfill the initial work program, and to fully evaluate Blocks 12/15, 13/11,
13/12 and 13/13, a loose grid of 2D seismic was purchased and interpreted.
Encouraged by the identification of conceptual leads at the Lower Cretaceous and
Upper Jurassic levels on this 2D it was decided to shoot a new high resolution 2D
seismic survey (with pseudo 3D processing) over the blocks to de-risk these leads.
Zeus commissioned Fugro to acquire these data in 2008.
Data for 11 exploration wells were also purchased for this evaluation. Subsequently
data were interpreted over the whole area, concentrating on the Lower Cretaceous
Scapa and Upper Jurassic Teviot and Buzzard intervals. Interpretation has been
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ZEUS PETROLEUM LIMITED
completed and has confirmed that there are no significant prospects to drill the
Contingent well on.
PROSPECTIVITY OF 12/15, 13/11, 13/12 & 13/13
The area of Blocks 12/15, 13/11, 13/12 and 13/13 largely covers an area known as the
Wick Basin. The potential for a working petroleum system has been examined within
the blocks. For this to be effective, hydrocarbons must be trapped in stratigraphic
closures in both the Upper Jurassic and Lower Cretaceous sands, as there is no
evidence of any significant, untested structural closures within the licence area.
As part of a group in an adjacent licence, Zeus has undertaken regional source rock
modelling using geochemical data from wells throughout the Inner and Outer Moray
Firth. This demonstrates that Devonian source rocks entered the ‘oil window’ at
around 4000 metres depth of burial in the Wick Basin. Similarly, the Upper Jurassic
source rocks entered the oil window at around 3600 metres and a limited hydrocarbon
kitchen can be mapped in the blocks at the base of the Upper Jurassic. Migrated
hydrocarbon shows have been identified in wells drilled outside the licence area and
on the periphery of the basin (12/14-1 to the west and 13/16-1 to the south).
Despite this potential for hydrocarbon generation, neither wells which have been
drilled in the licence and which penetrate the Devonian (13/11-1 and 13/12-1)
encountered any hydrocarbon shows in the Devonian or Jurassic section. The
conclusion from this evidence is that there is a restricted hydrocarbon kitchen within
the Wick Basin and that any generated hydrocarbons may have migrated outside of
the licence area. In addition, the new data confirms that the main NW-SE Little
Halibut Fault to the east of the Wick Basin and which runs through blocks 13/11 &
12, has been reactivated many times with evidence of disturbances up to the sea-bed.
Therefore, this provides the potential for a direct hydrocarbon conduit right through
to the surface in this direction, limiting the potential for hydrocarbon migration into
the eastern part of the licence.
Mapping of the Upper Jurassic and Lower Cretaceous events provide evidence of a
series of sands which have the potential to form stratigraphic traps if encapsulated in
sealing shale. Although the wells in this area show that good quality reservoir sands
are abundant there is limited evidence of effective lateral seal and thus any
stratigraphic trapping mechanism remains highly uncertain. Well 13/11-1 tested the
Upper Jurassic Volgian section and demonstrated the presence of significant sands
but due to the absence of any shows there is no evidence that hydrocarbons reached
this area.
The recent seismic data has helped to define a potential Lower Cretaceous ‘Scapa’
package in 13/11, which does not continue along the major fault into 13/12 as
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previously interpreted. There is some evidence to suggest that the Scapa may be
present along the intersecting E-W trending fault that bounds the Piper prospect, but
this is outside of the licensed area. The presence of Scapa sands and consequent seal
are highly speculative and based on analogous features and basinal architecture where
the Scapa sands have been drilled further east in quad 14 (figure 3). With no
equivalent section having been encountered in the more proximal and sand-prone
target area around the licence, even the identification of similar packages would
represent a high risk in the absence of information regarding seal, probably the most
critical parameter of the play. The suggested Scapa packages, confirmed by the new
data, indicated insufficient character to identify reflectors or intervals that may have
represented lithology changes sufficient to act as potential seals. As such, the risk on
such plays would be unacceptable with the present level of knowledge.
Fig 3:
Reserves Summary
Following this review of the licence, the only remaining potential in the licences that
could be charged by the Wick Basin involves the Scapa play. As mentioned above,
with the current level of knowledge of this particular play and reservoir, based on one
field under production and another under appraisal, the risk is unacceptably high.
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Scapa Lead
Type: Stratigraphic pinchout at near BCU level against the Little Halibut Fault.
Risks:
•
•
•
•
Structure: Defined by pseudo 3D seismic. Risk of structure is moderate but
there are significant uncertainties on GRV. (0.6)
Source/Migration: Restricted Kitchen in Block 13/11. Oil shows have not
been recognised in nearby wells – maybe not on migration pathway. Risk of
suitable source and migration path is moderate to high. (0.5)
Seal: Lead is likely to leak if there is connectivity to sands higher in the
section. The trap is stratigraphic and there is a significant risk on top seal at
the location. Seal risk is high. (0.2)
Reservoir: Lower Cretaceous Scapa sediments are postulated within the
mapped seismic package. Not identified in nearby wells. Reservoir risk is
moderate to high. (0.3)
Overall Risk = 0.018 or 1 in 55
Reserves Summary:
Min. 14 mmbbls
M.L. 71 mmbbls
Max. 227 mmbbls
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