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P1628 (29/7b) Relinquishment Report - January 2011 1
P1628 (Block 29/7b)
Relinquishment Report
January 2011
P1628 (29/7b) Relinquishment Report - January 2011 2
CONTENTS
1. Licence Data ............................................................................................ 3
2. Synopsis ................................................................................................... 3
3. Exploration Activities ................................................................................ 3
4. Prospectivity Analysis ............................................................................... 4
5. Reserves Summary .................................................................................. 5
6. Maps and Figures ..................................................................................... 5
7. Clearance ................................................................................................. 7
P1628 (29/7b) Relinquishment Report - January 2011 3
P1628 (29/7B)
RELINQUISHMENT REPORT
1. Licence Data
Licence Number P1628
Licence Round Award effective from 20-06-2009
Licence Type Traditional
Block Number 29/7b
Operator/Partner % Premier Oil (100%)
Work Programme Summary Reprocess seismic during initial period.
Drill or Drop decision on well by June
2011
2. Synopsis
Licence P1628, Block 29/7b was acquired by Premier Oil Plc (operator)
effective from 20th June 2009. The license area contained one Palaeocene
discovery, and a Palaeocene lead. The initial term (ending 19th June
2013) requires a drill or drop decision by June 2011. The firm commitment
to reprocess seismic data during the initial period has been fulfilled (Figure
1).
3. Exploration Activities
Full seismic mapping & rock physics modelling was carried out over the
entire licence by Premier. In order to assess the Palaeocene lead, Gladius,
and determine the remaining prospectivity surrounding the Palaeocene
discovery well (29/7-1), 185 sq km of seismic data were reprocessed using
Baker-RDS:
• Offset stacks Near, Mid, Far
• Peak frequency enhancement to 55Hz
• Coloured inversion of high frequency near and mid offset stacks
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4. Prospectivity Analysis
Discovery well 29/7-1 found oil bearing sands in the Cromarty and Odin
Members of the Sele and Balder Fm. (Scutum prospect hereafter). Oil
shows throughout the Chalk section could provide a potential upside to the
Scutum prospect.
The trap at Scutum is a four-way dip closure over a deeper Zechstein salt
swell. Both reservoir intervals are interpreted to be thin turbiditic sheet-like
sands, which were deposited between positive relief provided by the salt
swell and a resistant Maureen marl to the north/north-east. The axis of
deposition is thought to have run west-east, causing the sands to thicken to
the north, down dip of the discovery well. However, they pinch out towards
well 29/7-3, where they are not encountered. The sands are below seismic
resolution, and are not visible on reprocessed, frequency enhanced seismic
data sets. Although the discovery well noted an ODT in these sands, FIT
samples from the Cromarty Sands indicate there is mobile formation water
present close to the crest of the structure (Sw~0.49 %), and pressure
points suggest that these brines are close to, or coincident, with a regional
aquifer gradient. This limits the depth of the potential OWC to the P90
contour, which is non-economic at this time (Figure 2).
Residual oil throughout the Palaeocene Chalks could be prospective after
stimulation, as demonstrated at Curlew C (Shell) (Figure 3). However, this
structure was deemed too small to add sufficient upside to the Scutum
prospect.
The Palaeocene (Lower Maureen) Gladius lead previously identified to the
north-east, was shown to be non-prospective. Rock physics analysis
suggests the bright amplitudes observed on both near and far stacks are
indicative of lithological phenomena (marl), not hydrocarbon presence.
The decision to relinquish the licence became effective on 10th January
2011.
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5. Reserves Summary
Scutum
P90 P50 P10
OWC (m TVDss) 2467 2530 2550
GRV (Balder - Lista) (10^6 m3) 45.9 122 324
Ave Sw (Odin & Cromarty) (%) 40.3 46.8 51.5
N:G % 13.6 15.6 18.0
Average Porosity % 24.6 27.8 31.2
RF (%) 25 25 25
WEST Lead P90 P50 P10
STOIIP (MMbl) 5.4 14.9 41.4
OIP (MMbl) 1.3 3.7 10.4
6. Maps and Figures
Figure 1 - DECC map showing Licence boundaries and Field Determination Area P1628,
Block 29/7b (blue; produced January 2011).
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Figure 2 - Balder Depth Map (TVDss; CI = 10 m), with P90 closure (4.5 sq km) and most
likely OWC (2467 m TVDss - defined by ODT in well 29/7-1 and Cromarty FIT
sample/pressure data which indicated formation water with pressures in agreement with a
regional (Bittern Field) brine gradient).
Figure 3 - Ekofisk Depth Map (TVDss; CI = 20 m), with P10 closure (19 sq km) and potential
ODT in Ekofisk Fm., (2700 m TVDss - defined by ODT in well 29/7-1).
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Figure 4 - Arbitrary S-N Near Stack Seismic Line through Curlew A showing Palaeocene
leads (Cromarty & Ekofisk). Polarity is European; An increase in acoustic impedance is a
negative trough. Balder Fm - Gold; Maureen marl slump - Black; Ekofisk Fm - Blue; Plenus
Marl Fm - Pink; Kimmeridge Clay Fm - Green.
7. Clearance
Premier Oil gives DTI the right to publish the relinquishment report.
S N
1 km
S
N
Scutum