Licence P1853 Relinquishment Report - Log In · The contrasting segments of continental crust along the margin display differences in, for example, the degree of crustal stretching,

Licence P1853

Relinquishment Report

February 2015

Document last updated 26-02-2015 14:40 CET

Relinquishment report


1 Key Licence History 1

2 Database 3

3 Geological Overview 7

4 Prospectivity Evaluation 15

5 Conclusions 25

6 Clearance 25

List of figures

1.1 P1853 Licence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 P1853 Partial Relinquishment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.1 Seismic Database . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Seismic Comparisons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1 Regional topography/bathymetry map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2 Regional gravity map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.3 Regional magnetic map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.4 Regional structure map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.5 Regional structure map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.6 Regional igneous margin map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.7 Regional igneous margin map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.1 Seismic Line across Grouse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.2 Grouse Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 4.3 Grouse to Tobermory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.4 Grouse Chronostratigraphic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.5 Grouse AVO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4.6 High Resolution Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 4.7 Electro-Magnetic Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.8 Grouse Volumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 4.9 P1853 Additional Prospectivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

List of tables

2.1 O f f s e t W e l l D a t a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1 V o l u m e p a r a m e t e r s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4.2 G r o u s e R i s k i n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

1 Key Licence History

Licence Details Licence P.1853 was awarded to Faroe Petroleum (Operator, 37.5% equity) on 10th January 2011, with joint venture partners E.ON E&P UK Limited (37.5%) and Idemitsu (25%). This was a 26th Round Traditional Licence, with an initial term of 4 years.

The licence comprised blocks 217/11, 12, 13, 16, 17, 18, 19, 20, 218/11, 12, 16, 17 and 22.

During the 27th Round the same group applied for and was awarded blocks 217/14 and 15. These blocks were rolled into the P1853 licence with the same end of the initial term. The blocks that composed P1853 are shown in Fig. 1.1

Fig. 1.1 P1853 Licence. Map showing the P1853 licence. The pink shaded blocks are those awarded in the 26th round. The two unshaded blocks were added in the 27th round

Work Programme The work programme commitments, completed within the initial term involved:


1

Firm commitments The work programme for the blocks awarded in the 26th Round consisted of

Acquire a minimum of 300km of long offset 2D seismic data License a minimum of 100km of long offset 2D seismic data Reprocess 200km of long offset 2D seismic data Post well study of Lagavulin well Miocene section focusing on data acquired from drilling, cuttings & available real-time logs.

As part of the application for the blocks awarded in the 27th round the partnership committed to

Acquire an Electro-Magnetic survey covering the main Grouse prospect to confirm hydrocarbon presence

Drill-or-drop Drill one well to reach the top of the Balder Formation or to a minimum depth of 2,500m, whichever is shallower, or relinquish the licence after the initial term.

Relinquishment Partial relinquishment of the licence was made at the end of Year 3, on 31st December 2013. The blocks relinquished are shown in Fig. 1.2

Fig. 1.2 P1853 Partial Relinquishment. The retained blocks are highlighted in green. The pink outline shows the Grouse prospect.


2

After full analysis of the prospectivity, the remaining part of P.1839 was relinquished with an effective date of 9th January 2015.


3

2 Database

2D Seismic Database while no 3D exist in the area, Faroe Petroleum has access to extensive library of 2D seismic data. Fig. 2.1illustrates the seismic database used in this application. All the seismic data within the North Corona area consists of only 2D data, with a mix of a number of vintages. Included in this database are the more recent surveys; namely: FSB99, FSB2000, NSBI98 and CU05OU, which form the bulk of all data available. These more recent surveys are of much high quality, in terms of signal penetration and have a much higher signal-to-noise ratio. In addition to the conventional 2D seismic data , in July 2014 Faroe Petroleum acquired 20 lines of high resolution seismic data. Such data are typically acquired as part of a site survey, but given the shallow depth of the Grouse anomaly, they can be used as part of the assessment of Grouse.

Fig. 2.1 Seismic Database. Map showing the seismic database used in the evaluation of the P1853 licence.

Seismic Reprocessing The main seismic data available in the region is commercial multi-client surveys acquired and processed by a number of different seismic contractors and is of varying vintage and quality. It is common that commercial surveys are subject to 'vanilla' type processing, which may not be optimal for the specific imaging challenges and target levels found within the application area. As part of the evaluation of the P1853 licence nearly all of the seismic data has been reprocessed. The reprocessing has largely focussed on better defining the Grouse prospect. The evolution of the processing can be shown by the example in Fig. 2.2. This shows the evolution from the contractors original reprocessing focussed on the sub-basalt, through a conventional reprocessing sequence and then a broadband reprocessing of the data. This can be compared to the high resolution line acquired to directly overlie this line.

Well Database Faroe Petroleum had access to all released wells in the area. There are currently very few wells drilled within the vicinity of the North Corona area. The table below (Table 2.1 list the closest wells of relevance used within this application. The nearest well to the application area is the recent (2011) Lagavulin well located 10km to the North on the Pilot Whale anticline. After this, the next closest wells are located 80 km to the southwest (214/4-1) and 60 km to the east (219/21-1). Although there are only three wells in the immediate vicinity of the Grouse prospect (217,15-1, 214/4-1 and 219/21-1) the rest of the wells in this table were used to help form the understanding of the Faroe-Shetland basin region geology.217/15-1 (Lagavlin) Discussion. The Lagavulin well, drilled by Chevron in 2010, is the most recent and closest well to the Grouse prospect. It was targeted at sub-basalt prospectivity and subsequently TD'd in the Paleocene Basalts. Despite finding no reservoir, it did encounter oil shows and elevated gas readings indicating the presence of a working hydrocarbon system. Unfortunately due to inherent design, the well was drilled riser-less through the Eocene section and therefore no cuttings or LWD logs were taken over the prospective Grouse interval. It was however noted that a slight pressure ramp was encountered around the Mid-Miocene unconformity which supports the view of a regional top seal event (also supported by termination of regional gas chimney's). Other than this the well has delivered very little geotechnical support to the Grouse prospect and evaluation of the new play.


4

Fig. 2.2 Seismic Comparisons. The evolution of the processing can be seen from the original acquisition in 2000 through to the broadband processing in 2014. The hi-res line directly overlies the seismic line. Seismic line is reproduced by kind permission of TGS.


5

Table 2.1 Offset Well Data.. Although there are only three wells in the immediate vicinity of the Grouse prospect (217,15-1, 214/4-1 and 219/21-1) the rest of the wells in this table were used to help form the understanding of the Faroe-Shetland basin region geology.


6

3 Geological Overview

Regional Geological Setting

The North of 62°N (North Corona) area is a relatively deep water and under-explored frontier of the UK continental shelf (Fig. 3.1 Fig. 3.2 and Fig. 3.3). So far, only one deep exploration well - 219/21-1 (Shell) - has been drilled within the area; this tested heavily intruded Upper Cretaceous mudstones within the Ben Nevis Dome and was dry. However, there are a number of encouraging factors that make this area attractive for hydrocarbon exploration, including the presence of large structures with trapping potential and the potential for good reservoir rocks and mature source rocks. The North Corona area lies within the passive margin of Northwest Europe . There is a natural segmentation to this margin, which reflects the complex history of continental breakup and seafloor spreading. The contrasting segments of continental crust along the margin display differences in, for example, the degree of crustal stretching, the prevalence of igneous centres and the effects of post-breakup compression (Fig. 3.4 Fig. 3.5 Fig. 3.6 and Fig. 3.7). The general plate setting and tectonic evolution of the North Corona area is well documented (e.g. Doré et al., 1999; Coward et al., 2003). Basement terrain's began assembling during Proterozoic times, culminating at the end of the Caledonian Orogeny during the early Devonian (e.g. McKerrow et al., 2000; Strachan et al., 2002). Subsequently, the region was influenced by rifting episodes. Within the North Corona region, rifting occurred mainly during mid to late Devonian, Permo-Triassic, Jurassic, Cretaceous and locally, early to mid Paleocene times (e.g. Smallwood and Gill, 2002; Coward et al., 2003). Extension initially focused on the northeast-southwest trending Caledonian basement grain and the locus of rift activity appears to have migrated in a northwesterly direction through time, towards the present location of the Northeast Atlantic Ocean (Doré et al., 1999). Considerable uncertainty remains regarding the timing, duration and significance of many of the postulated rift events. This is due to a combination of a lack of adequate deep well control and the poor seismic definition of the deep structure of the basin associated with the widespread Palaeogene volcanic and intrusive rocks. During earliest Eocene times, renewed rifting, possibly facilitated by the presence of the Iceland plume (e.g. White, 1988), resulted in continental break-up between Northwest Europe and Greenland, leading to the formation of the present day Northeast Atlantic Ocean. The break-up process is linked with extensive and widespread mainly continental volcanism and intrusive activity during latest Paleocene to earliest Eocene times (e.g. White and McKenzie, 1989). Oceanic spreading between eastern Greenland and Northwest Europe commenced at approximately 55 to 54 Ma (Saunders et al., 1997) along the Reykjanes, Aegir and Mohns spreading ridges. A Palaeogene phase of uplift reported along the Northwest European continent-ocean boundary has been related to the presence of underplated igneous material associated with the development of the North Atlantic Igneous Province (e.g. Morgan et al., 1989; White et al., 2005). Following separation of eastern Greenland from Northwest Europe, the Northeast Atlantic margin is regarded as a passive margin although it has been far from tectonically quiescent (e.g. Stoker et al., 2005). During latest Paleocene to Miocene times, regional compressive forces resulted in the widespread growth of anticlines and dome-like structures (e.g. Lundin and Doré, 2002; Ritchie et al., 2003; Johnson et al., 2005) (Fig. 3.6). During early Pliocene times, a further localised phase of compression is postulated within the Northeast Faroe-Shetland Basin (Ritchie et al., 2003). Contemporaneous regional epeirogenic uplift and tilting of the Northeast Atlantic continental margin was accompanied by accelerated offshore subsidence and the progradation of sedimentary wedges (Andersen et al., 2002; Stoker et al., 2005).


7

002230

10°E5°E0°5°W10°W15°W

70°N

65°N

60°N

55°N

Area depicted in Figures 6 and 8

Fields

Discoveries

‘North Corona’ area

Legend

Clair

Tobermory

Rosebank &Lochnagar

CamboSchehallion

FoinavenHa tton B an k

R ockall BankHatto

n Trough

R ockall Trough

Faroe-Iceland

R idge

Faroe-S

hetland C

hannel

Wyville Thomson Ridge

Norwegia

n

B as in

Lofote

n B as in

Iceland

B as inFaroeShelf

Møre

B as in

Vøring

B as inTr

øndelag

P latfo

rm

Kol

bein

s ey

Rid

ge

Central Jan Mayend FZ

West Jan Mayen FZ

Mohns

Ridge

East Jan Mayen FZ

North R ockall

B as in

Fig. 3.1 Regional topography/bathymetry map


8

002231

10°E5°E0°5°W10°W15°W

70°N

65°N

60°N

55°N


Faro

e

Platfo

rm

Møre

Basin

HaHattotton n HiHighghVør

ing

Basin

Rockall

Hig

hHatton B

asin

Rockall Basin

Iceland

Basin

Norweg

ian

Basin

North Rockall

Basin

Faroe-Iceland

Ridge

Faro

e-She

tland

Bas

in


Jan

May

en

mic

roco

ntin

ent

Aeg

ir R

idge

(ext

inct

)Ko

lbei

nse

y

Rid

ge

est Jan Mayen FZ

MoRRiiddggee

Trøn

dela

g

Plat

form

East Jan Mayen FZ

Lofoten

Basin



Legend

Whns

Fig. 3.2 Regional gravity map. Note the principal geological features highlighted


9

002233

10°E5°E0°5°W10°W15°W

70°N

65°N

60°N

55°N



Legend

)tcnit

xe( egdiR rigeA

Moh

Ridge

Rid

ge

Kol

bein

sey

West Jan Mayen FZ

East Jan Mayen FZ


Marginal magnetic high

Faroe-Iceland

Ridge

5

6

22

7 2120

23

18

13

24

15

24B

23?

24A

22?

20

5

18

24A

21

24B

5

22

55

21

20

23

22

20

22

13

22

2215

20

6

20

137

23

21

18

6

24B


Faro

e

Platfo

rm

Møre

Basin

Vørin

g Bas

in

Rockall

Hig

hHatton B

asin

Rockall Basin

Iceland

Basin

Norweg

ian

Basin

North Rockall

Basin

Faro

e-She

tland

Bas

in


Trøn

dela

g

Plat

form

ns

Fig. 3.3 Regional magnetic map. Note the principal geological features highlighted


10

10°E5°E0°5°W10 °W15 °W

70°N

65°N

60°N

55°N

FAROE - ICELAND

RIDGE

JAN

M

AY

EN

M

ICR

OC

ON

TIN

EN

T

SNHOM EGDIR Jan Mayen Island

RRHHA

MA

ND

VD

FR

AD WTR

Legend

Land

Structural highs

Basins

Cenozoic domes

Igneous centres

Continental crust, undivided

Oceanic crust, undivided

HHA

MA

ND

VD

Helland Hansen Arch

Modgunn Arch

Naglfar Dome

Vema Dome

RR

WTR

FR

AD

Reykjanes Ridge


Fugloy Ridge

Alpin Dome



Median line and designated areas

Continent ocean boundary

Ocean floor magnetic anomalies

Approximate southern limit of lavas

Spreading ridges (active and extinct)

Oceanic fracture zone

002234

Fig. 3.4 Regional structure map


11

Selected (Mesozoic) faults

Lineaments or transfer zones

BL

ML

EL

VL

CL


Structural highs

Mesozoic basins

Legend



Continent-ocean boundary


Selected wells

Lava escarpments, ticks on lower side

Igneous centres

Oceanic crust

0 40 8020 Km60

Cenozoic domes and anticlines

Brendan Lineament

Magnus Lineament

Erlend Lineament

Victory Lineament

Clair Lineament

2 °E0 °2 °W4 °W

64°N

63°N

62°N

218

217

219

63016303

222

6201

6203

63026300

210209208

216

214

6304

33

6204

63026301

211

6202

221

6202

223

213

346104

6299

220

64026403 6401

6200

6400

6300

6401 6402

209/12- 1

214/04- 1

214/09- 1

214/09-1

219/21- 1

CO

RO

NA

HIG

H MAGNUS

BASIN

FUGLOY RIDGE

Talisker Ridge

NORWEGIA

N BASIN

FBASIN

AROE-SHETLA

ND

BLML

EL

VL

CL

Pilo

t Wha

le

Ant

iclin

e

Norw

ay

UK

Faro

es

UK

Brendan BenNevisDome

ErlendWErlend

est

oeFar -Shet sl E ca nd arpmen t

2324B

22

ERLEND HIGH

MØRE

BASIN

MØ

RE

M

AR

GIN

AL

H

IGH

002235

Fig. 3.5 Regional structure map. A map illustrating the structural framework and including oceanic crust spreading centres, oceanic fracture zones, age of oceanic crust/oceanic magnetic anomaly number, continent/ocean boundary, continental crust with main sedimentary basins and structural highs


12

10 °E5°E0 °5 °W10 °W15 °W

70°N

65°N

60°N

55°N

5

6

22

721

20

23

18

13

24

15

24B

23?

24A

22?

20

5

18

24A

21

5

24B

5

22

5

21

20

23

22

20

22

13

22

2215

20

6

20

137

23

2118

6

24B

Legend




Continent ocean boundary



Lava escarpments

Seaward-dipping Reflectors

Igneous centre

Postulated Trail-Vøring igneous complex

Extent of lavas

Sill complex


Oceanic crust, undivided

Land

Spreading ridges (active and extinct)

Oceanic fracture zone

RR Reykjanes Ridge

FAROE - ICELAND

RIDGE

JAN

M

AY

EN

M

ICR

OC

ON

TIN

EN

T

SNHOM EGDIR Jan Mayen Island

RR

002235

Fig. 3.6 Regional igneous margin map. A map illustrating the limit of lavas, primary lava escarpments and igneous centres


13

2°E0°2°W4°W

64°N

63°N

62°N

218

217

219

63016303

222

6201

6203

63026300

210209208

216

214

6304

33

6204

63026301

211

6202

221

6202

223

213

346104

6299

220

64026403 6401

6200

6400

6300

6401 6402

209/12- 1

214/04- 1

214/09- 1

219/21- 1

Norw

ay

UK

Faro

es

UK

23

24B

22

Brendan

ErlendWErlend

est

oear -SF he ct sla End arpment

214/09- 1

Legend

Area of Interest


Continent-ocean boundary


Selected wells


Lava escarpments

Seaward-dipping Reflectors

Igneous centres

Extent of lavas

Cenozoic domes and anticlines

Sill Complex


Oceanic crust

002237

Fig. 3.7 Regional igneous margin map. A regional structural map focused on the North Corona area


14

4 Prospectivity Evaluation

Grouse Prospect

Given the remoteness of the P1853 licence it is clear that a very substantial volume would be required to justify the cost of any development. While a number of leads were identified it was clear early in the evaluation process that only one was of sufficient size to be an attractive drilling candidate. This was the Grouse prospect and this was the main focus of all the work done on P1853. The Grouse prospect is an amplitude defined prospect. A package of bright amplitudes is noticed below the Opal A-CT boundary Fig. 4.1 Bright amplitudes covering over 500km2 define a partially dip and partially stratigraphic trap Fig. 4.2. The stratigraphic element comes from the onlap and pinch out of the Grouse package on to the Pilot Whale anticline to the North and the Brendan's Dome to the East.

Fig. 4.1 Seismic Line across Grouse. FSB00RE09-403 SW- NE seismic line showing the bright amplitudes associated with the Grouse prospect. The line location is shown in the accompanying map. Seismic line is reproduced by kind permission of TGS


15

Fig. 4.2 Grouse Map. The contours show depth to Top Grouse in metres. The colour-fill shows the difference in amplitudes between the Top and Base Grouse events. Grouse is dip closed to the south, west and northeast and is stratigraphically trapped to the north and east

Grouse Depositional Models It is difficult to be certain at what stratigraphic level the prospect lies but the tie to the Tobermory well to the south (Fig. 4.3) indicates that most probably the package of bright amplitudes that make up the Grouse prospect sit in the Late Eocene or Early Oligocene section(Fig. 4.4). No sandstones have been identified in the Faroe-Shetland Basin of this age in any of the well penetrations. It is possible that the Lagavulin well (217/15-1) encountered sands of this age but no detailed logging was carried out and there were no returns to surface from the section above the basalt. Work by Faroe and E.ON has identified two potential models to explain the deposition of sands in the Grouse prospect.

Model 1 relies on remobilisation of Eocene sands deposited contemporaneously to the Portree, Caledonian and Strachan fans known from the area to the south of the Grouse prospect. Uplift and erosion of the Fugloy Ridge directly to the south and west of the Grouse prospect would have resulted in the deposition of sands into the Grouse prospect at the base of the slope on-lapping the developing Pilot Whale Anticline. Seismic evidence appears to support the likely presence of sands of similar age to the Caledonia fan within Faroese waters.

Model 2 invokes a siliclastic sand supply from the shelf area to the southeast of P1853 after T96-98 erosion of the shelf with incised valley feeder system and a depocentre at the base of the slope , on-lapping the developing Pilot Whale Anticline. A ready supply on sand on the shelf is demonstrated by a number of wells notably 210/04-1 which has a thick sequence of mid to late Eocene shoreface sands. No clear input channel has been identified on the seismic data, but given the sparseness of the data this is not entirely surprising.


16

Fig. 4.3 Grouse to Tobermory. The seismic line shows the relationship between the Grouse feature and the Tobermory discovery. The Grouse feature is interpreted as sitting within the latest Eocene or early Oligocene section. Seismic line is reproduced by kind permission of TGS


17

Fig. 4.4 Grouse Chronostratigraphic Diagram. The Grouse reservoir is interpreted as being deposited at the end of the Eocene.


18

Seismic Observations The main basis of the Grouse prospect is the observation of a package of bright seismic amplitudes. There seems to be a fairly consistent switch off amplitudes with depth (Fig. 4.2). Any variations from the consistent switch off with depth can be explained by the fact that the seismic is not 3D and that there are a number of different vintages of seismic data covering the prospect. A detailed analysis of the AVO response of the Grouse package is shown in Fig. 4.5. It can be seen that the response of the Grouse package is anomalous both in terms of Amplitude and AVO response. One aspect of the seismic data is difficult to reconcile with the presence of hydrocarbons, no clear flat spot is visible. A flat spot would be expected to be visible if hydrocarbons were present. Initially it was recognized that tuning effects would make it difficult to see any flat spot.

Fig. 4.5 Grouse AVO. The AVO response of the Grouse feature is anomalous both in terms of its amplitude response and its gradient response. Seismic line is reproduced by kind permission of PGS

In an attempt to better image the reservoir two approaches were tried, firstly using a broadband reprocessing technique on the some existing lines and secondly acquiring high resolution seismic lines. The results of these efforts can be seen in Fig. 4.6. It is apparent that while the top and base reflections are clearly imaged and separated. However, no flat spot can be observed. This is difficult to explain if the Grouse feature contained gas. Against this the seismic observations are difficult to explain, particularly the consistent switch off of amplitudes with depth. Given the uncertainty the lack of a flat spot when taken into account with the AVO observations tends to lead to an increased perception of risk for the Grouse prospect.


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Fig. 4.6 High Resolution Line. The high resolution data over Grouse clearly separates the Top and Base Grouse reflectors. The seismic response from the edge of the Grouse feature is complex but no clear flat spot can be observed.

Electro-Magnetics As part of the evaluation of the Grouse survey Faroe Petroleum contracted PetroMarker to acquire an Electro-Magnetic (EM) survey over the Grouse feature. In many ways Grouse is an ideal candidate for EM work. It sits very shallow within the section but is in deep water. These two factors both help the EM technique. A single line was acquire across the Grouse prospect. The results are shown in Fig. 4.7. There is clearly no marked EM anomaly associated with the Grouse feature. This was initially viewed as having a very negative impact on the Grouse prospect. However comparison with the Tobermory accumulation to the south showed that the hydrocarbons in that reservoir were associated with unusually low resistivity readings. The pay zone in the reservoir has a resistivity around 4-5 ohm-m. This is due to the unusual mineralogy of the reservoir which contains a number of conductive minerals. This means that it is still possible that there is a large hydrocarbon accumulation at Grouse despite the fact that there is no observable EM anomaly. Modelling of responses showed that the minimum level for detectable EM anomalies for a 20m thick body was around 10 ohm-m. The impact of the EM work while clearly not positive is also not damming and for the purposes of risking Grouse was seen as neutral to slightly negative.

Risk and Reserves It is clear that if the Grouse anomaly is caused by hydrocarbons it is very large. The areal extent of the bright amplitudes is more than 500km2. GRV was calculated using the top and base Grouse unit picks. The minimum case corresponded to a an assumption of lower velocities within the Grouse unit and was restricted to where the seismic amplitudes were brightest. The upside case corresponded to where the velocities within the Grouse unit were faster and assumed that the Grouse unit extended a little beyond the edge of the amplitudes. Furthermore as the reservoir is very shallow the parameters are likely to be very good. The ranges used for the reservoir parameters are given in Table 4.1. This gives the reserve distribution seen in Fig. 4.8. The mean volume is 4.5tcf. Risk for the prospect is difficult to assess. The final risking and the reasons for the risking are shown in Table 4.2.


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Fig. 4.7 Electro-Magnetic Results. The illustration shows the constrained inversion results for the EM line acquired over Grouse. The highly resistive basalts can be seen at the bottom of the section. No resistive body can be seen at the Grouse level at around 22000-2300m

Table 4.1 Volume parameters


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Fig. 4.8 Grouse Volumes

Table 4.2 Grouse Risking


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Drilling Drilling the Grouse prospect is not a trivial task. The combination of very deep water, unconsolidated formations and a reservoir likely to be at pressures close to the seal capacity of the overburden make the design of any well on Grouse challenging. However some initial design work showed that it would be possible to drill the prospect using 3 casing strings. The likely cost of this well wold be around £25M

Development While the potential volumes for Grouse are clearly impressive it was not clear initially how any volume sitting so close to the sea bed in such deep water would be developed or indeed even if it was possible to develop such an accumulation. To address this issue ADIL were contracted to assess potential development scenarios. The approach taken was very conservative. No novel engineering solutions were relied on and all the elements of the proposed development scenario had a proven track record. This work showed that it would be economically viable to develop volumes greater than 1.7tcf. The proposed development would consist of 4 long flow lines radiating out from a central processing facility. This would be either a spar on semi sub. Gas would then be exported to Magnus and then into the pipelines that run from there back to shore.

Additional Prospectivity In addition to the main Grouse Prospect, a number of other leads have been identified within the P1853 Licence area and their locations are shown in Fig. 4.9 are described below.

Fig. 4.9 P1853 Additional Prospectivity. The map shows the locations of additional leads identified within the P1853 Licence.


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Grouse West Lead The Grouse West Lead is located due west of the Grouse Prospect. Grouse West can be viewed as the a westward extension of the Grouse prospect. The bright amplitudes correspond with the mapped spill point to the southwest. However the amplitudes are not as bright and the package not as thick as in the main Grouse prospect. The Grouse West Lead covers an area of almost 300 km2. Using similar reservoir parameters to the Grouse Prospect and a net reservoir thickness of around 20 m, would imply a potential unrisked mean recoverable gas reserves of around 1.6 Tcf.

Perdigoa Lead The Perdigoa Lead is partly located directly underneath the Grouse Prospect. It is defined by an amplitude brightening observed within the Middle Eocene Strachan equivalent section. The lead is formed by a simple roll-over in a southwest-northeast direction and pinchout in the up-dip direction to the southeast. It is interesting to note that the amplitudes appear to dim at roughly the same depth as those observed within the Grouse Prospect and this could indicate that the Strachan section is in pressure communication with the overlying Grouse interval. The Perdigoa Lead, defined by this amplitude anomaly, covers an area of approximately 80 km2.

Ptarmigan Lead The Ptarmigan Lead is also partly located directly underneath the Grouse Prospect. It is a northwest-southeast elongate anticline, of most likely Jurassic age. It is overlain by a moderate thickness of basalt in a setting which coincides with the basalt escarpment (Faroe-Shetland Escarpment). Consequently it is regarded as a lead, as there are a number of large uncertainties, namely:

The age of the mapped event with its associated reservoir The thickness of the overlying basalt The poor quality seismic data, particularly beneath the basalt layer (Fig. 3.22) The Base Basalt interpretation, as the main Ptarmigan depth structure is very dependent on the accuracy of both the mapped basalt thickness and the applied velocity model

The prospect covers an area of up to 160 km2, and using simple deterministic reservoir parameters, results in an potential unrisked mean recoverable oil reserve of approximately 200 MMbbl. Oil is regarded as the most likely fluid. Following the drilling of the Lagavulin well this lead is regarded as very high risk since it is drilling a similar but smaller structure.


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5 Conclusions

It is clear that given the 1.7tcf minimum economic volume that the Grouse prospect is the only commercially interesting target. The volumes associated with the prospect are certainly significant. However the high risk assigned to the Grouse prospect means that neither of the partners would be prepared to drill with their current large equities. Attempts to farm out the prospect did not meet with any success. As such while recognizing the potential of the licence, E.ON and Faroe have chosen to relinquish the licence.


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6 Clearance

Faroe Petroleum as operator has approved this relinquishment report for publication by the DECC.

Documents

Licence P1853 Relinquishment Report - Log In · The contrasting segments of continental crust along the margin display differences in, for example, the degree of crustal stretching,