Final Relinquishment Report Licence P1800 UKCS … · Final Relinquishment Report Licence P1800...

P1800 Relinquishment Report 1

Final Relinquishment Report

Licence P1800

UKCS Blocks 22/17a and 22/22d

Idemitsu Petroleum UK Ltd.

April 2015 Compiled by: CNS Team (CNS Team Leader: D. Waters) Idemitsu Petroleum UK Ltd.


Contents

1 LICENCE INFORMATION .........................................................................................................................3

2 LICENCE SYNOPSIS ................................................................................................................................3

3 WORK PROGRAMME SUMMARY ...........................................................................................................4

4 DATABASE ...............................................................................................................................................6

4.1 Well database ......................................................................................................................................6 4.2 Seismic database & Inversion products............................................................................................6

5 PROSPECTIVITY UPDATE .......................................................................................................................6

5.1 Eocene..................................................................................................................................................8 5.2 Upper Palaeocene ...............................................................................................................................8 5.3 Chalk & Lower Cretaceous. .............................................................................................................. 10 5.4 Late Jurassic ..................................................................................................................................... 10 5.5 Palaeozoic .......................................................................................................................................... 17

6 FURTHER TECHNICAL WORK UNDERTAKEN .................................................................................... 17

6.1 Basin modelling ................................................................................................................................. 17

7 RESOURCE AND RISK SUMMARY ....................................................................................................... 17

8 CONCLUSIONS ....................................................................................................................................... 19

9 CLEARANCE ........................................................................................................................................... 20

10 ABBREVIATIONS USED......................................................................................................................... 20

11 CONTACT DETAILS ............................................................................................................................... 20

Table listing Table 1: Licence synopsis ...................................................................................................................................... 3 Table 2: Seismic database .................................................................................................................................... 7 Table 3: Notional Syros Well details..................................................................................................................... 16 Table 4: Prospectivity summary .......................................................................................................................... 18 Table 5: Summary of risks for remaining prospects/leads .................................................................................. 19

Figure listing Figure 1: Map of remaining licence prospectivity .................................................................................................. 4 Figure 2: Stratigraphic column and prospectivity, blocks 22/17 & 22/22 .............................................................. 5 Figure 3: Seismic and well database .................................................................................................................... 7 Figure 4: Comparison of the seismic surveys, PGS MSP & CGG Cornerstone/Broadseis .................................. 8 Figure 5: 22/16b-5 Logs ......................................................................................................................................... 9 Figure 6: "Hydrocarbon Stack" as a Cromarty oil indicator, on PGS MSP data ................................................... 9 Figure 7: dBGT attribute Near Top Sele, CGG on Cornerstone and BroadSeis data (CGG) .............................. 10 Figure 8: Jurassic well correlation interpod play ................................................................................................. 11 Figure 9: 22/17-4Z Fulmar & Ribble Petrophysics ............................................................................................... 11 Figure 10: PGS MegaSurvey Plus arbitrary line, key Fulmar Targets (PGS MSP) ............................................ 12 Figure 11: 22/17-4Z Godwin discovery well seismic tie, MS plus (PGS) ............................................................ 13 Figure 12: Syros-Godwin Smith Bank Pod morphology (TWT) ........................................................................... 13 Figure 13: Syros & Godwin Pressures and Top Fulmar Depth ............................................................................ 14 Figure 14: Fulmar interpod definitions from Fulmar amplitude (PGS MSP) and impedance (mainly CGG Cornerstone) ......................................................................................................................................................... 14 Figure 15: Syros Impedance dip section (Cornerstone data set basis - CGG) .................................................... 15 Figure 16: Godwin-Syros Impedance arbitrary line section (Cornerstone data set basis - CGG) ....................... 15 Figure 17: Dip section through "Shawsgate" Lead (Cornerstone – CGG) ........................................................... 16 Figure 18: R1 Rotliegend Prospect seismic section (Cornerstone – CGG) ........................................................ 17


1 LICENCE INFORMATION

P1800 was awarded 100% to Idemitsu on January 10th 2011 as part of the UK 26th offshore licencing round. This was a traditional licence award with a four year term, and consequently the licence expired on 10th January 2015. The blocks involved (as designated at the time of award) were 22/17a and 22/22d located on the eastern flank of the Montrose-Arbroath High (MAH) where it adjoins the West Central Graben (WCG) in the Central North Sea (CNS) – see Figure 1: Map of remaining licence prospectivity. Where appropriate, permissions to publish have been obtained from the relevant vendors, including PGS and CGG.

2 LICENCE SYNOPSIS

The main 26th Rd commitments made on the licence were

a drill-or-drop to the shallower of the base Tertiary or 2900 m.

to obtain 145 km2 of 3D (the area of both blocks combined). The commitment was met with 145 km2 of CGG Cornerstone 3D and Broadseis data.

Table 1: Licence synopsis

Early leads at Upper Palaeocene level consisted of amplitude and preliminary AVO analysis anomalies that were coincident with pinch-outs and/or structural noses. At Jurassic level, amplitude responses signalled several Upper Jurassic leads of an interpod and combined interpod/fault seal nature, and one small 4 way closure (see Figure 1: Map of remaining licence prospectivity). Fulmar sands form the main reservoir objective at this level, but prospectivity is also recognised for the Upper Jurassic Ribble and Freshney sands – particularly in more basinal areas. Key prospective intervals are illustrated in Figure 2: Stratigraphic column and prospectivity, blocks 22/17 & 22/22. During Idemitsu’s tenure on the licence, additional CGG Cornerstone 3D and Broadseis data was purchased to allow greater delineation of the Upper Jurassic. At the same time, highly relevant wells on the neighbouring Jurassic interpod play discoveries were released, including Cayley, Godwin, and Shaw. Godwin in particular significantly de-risked the Upper Jurassic interpod play on the licence, and two new prospects Syros and Sicily were identified from the greater Upper Jurassic resolution on the acquired datasets. However, detailed rock physics analysis of the newer datasets, downgraded the likelihood of an HC AVO response within the upper Palaeocene leads.


Figure 1: Map of remaining licence prospectivity

Idemitsu has retained 100% equity throughout its tenure on the licence. Idemitsu wished to drill the Syros prospect and identified a suitable well location, but not at 100% exposure. Attempts to farm-down to 50% were unsuccessful leading to eventual relinquishment. Idemitsu would be interested in discussions with interested parties wishing to progress this now open acreage.

3 WORK PROGRAMME SUMMARY

Initial regional interpretation of the licence was carried out pre-award on the PGS MegaSurvey Plus PSTM data. Preliminary attribute analysis work identified promising anomalies in the Upper Palaeocene, including potential pinch-outs of the Cromarty sandstone, and smaller closures at Cromarty and Forties level. Preliminary depth conversion and attribute analysis work also identified a number of leads at Jurassic level including the Syros and Sicily Prospects. Upon award, a full suite of geological studies were initiated. Full PVT and Sw data assembly utilised all offset field data at Palaeocene and Jurassic levels. Core data analysis and petrophysical analysis of key wells was undertaken. Biostratigraphic, sequence stratigraphic, and facies correlation work was initiated including non-proprietary and proprietary Ichron biostratigraphic studies. The key wells used at various stratigraphic levels are shown in Figure 3: Seismic and well database.


Figure 2: Stratigraphic column and prospectivity, blocks 22/17 & 22/22

The CGG 3D Cornerstone data, including four angle stacks, was delivered to Idemitsu in April 2012. This was followed closely in May 2012 by release of the Cayley wells 22/17-3, 3X, 3Y, 3Z. The CGG Broadseis data was delivered to Idemitsu in August 2012. Relevant petrophysical, PVT, and rock physics analyses of the Jurassic interval in the Cayley wells were undertaken, and these wells were integrated into new interpretation of the CGG Cornerstone data. Two depth conversion models were applied using the CGG Cornerstone data to investigate sensitivity to depth conversion method:

1. A three layer model formed the base case, with intervals: sea floor to BCU, BCU-KCF and KCF-Top Fulmar.

2. Another five layer model also utilised sea-floor to Top Sele, Top Sele to Top Chalk, and Top Chalk to BCU.

Prospect resources at were found to be relatively insensitive to depth conversion method. Meanwhile, spectral decomposition work on the CGG Cornerstone dataset facilitated greater fairway delineation at the Tay/Cromarty/Forties levels. Armed with a new interpretation at deeper levels, an in-house basin modelling project was undertaken (see Section 6.1), to assist phase prediction in the various leads and address concerns about a relative lack of lack of fault migration pathways from basinal parts of the licence into Palaeocene objectives. In early 2013, utilising the new CGG Cornerstone 3D and Broadseis data, a major rock physics project was directed at the Palaeocene prospectivity, conducted in house by Idemitsu with support from PGS Reservoir. P-impedance volumes, Vp/Vs volumes and derived “HC stack” volumes were generated, as well as AVO attribute maps. These studies successfully extracted low Vp/Vs and high “HC stack” responses for known Forties accumulations in the area, but a lack of response in the Cromarty sandstone leads on the licence downgraded this prospectivity. Work was therefore widened to review prospectivity in targets secondary to the upper Palaeocene and Upper Jurassic, most notably within the Eocene Tay Formation, Chalk, and Palaeozoic prospectivity within Zechstein carbonates and Rotliegend Auk Formation (see Figure 2: Stratigraphic column and prospectivity, blocks 22/17 & 22/22).


As evaluation proceeded on the new CGG Cornerstone data, it became increasingly evident that attractive new prospectivity (Sicily and Syros prospects) in the far eastern areas of the licence required critical calibration with the nearby Godwin Discovery wells 22/17-4 & 4Z. An additional 95km2 of CGG Cornerstone 3D was acquired off the licence area to facilitate this calibration. New petrophysical, PVT, and rock physics analyses were then undertaken on the Godwin wells, and the synthetics & ties were integrated into interpretation of the extended CGG Cornerstone data set. A post-stack inversion (maximum likelihood sparse spike) further confirmed prospectivity at Fulmar level – with the Syros prospect being considerably enlarged and de-risked by the calibration with Godwin discovery. A preliminary well location and prognosis was made (21/17b-E) for the Syros prospect and a farm-down process was initiated. Further work on Rotliegend and Zechstein prospectivity matured to the R1 lead in late 2013 (see Figure 1: Map of remaining licence prospectivity). New well data from the Shaw discovery was also released in January 2014, and petrophysical analysis on the relevant wells (22/22a-7, 7Z, 7Y) was completed. A further look at chalk potential, including wells 22/22a-1, 22/22b-4Z, 22/23b-1, and the Banff and Machar fields was also undertaken. Likewise the Eocene potential incorporating Gannet and Milburn analogues were reviewed. No significant prospectivity was identified at these levels.

4 DATABASE

4.1 Well database The key wells used to understand the various stratigraphic levels of the licence are shown in Figure 3: Seismic and well database. It includes key well synthetics and well ties (IPUK), core data analysis (IPUK), petrophysical analysis, (IPUK), rock physics studies (IPUK & PGS), pressure data (IHS, CDA), as well as biostratigraphic, sequence stratigraphic, and correlation work (Ichron & IPUK).

4.2 Seismic database & Inversion products The key seismic datasets obtained are shown in Figure 3: Seismic and well database and listed in Table 2: Seismic database. The associated inversion products were also derived: Inversion products derived from PGS MegaSurvey Plus PSTM

o In house preliminary inversion at Paleocene level (Idemitsu) o Palaeocene P-impedance, Vp/Vs, HC stack volumes (IPUK exclusive study with PGS)

Inversion products derived from CGG Cornerstone and Broadseis o Fulmar Post stack maximum likelihood sparse spike (in house)

The PGS MegaSurvey Plus (MSP), CGG Cornerstone, and CGG Broadseis data sets were all useful products for analysis of the licence. A decision to obtain CGG Cornerstone and Broadseis was driven by a need to better resolve Intra-Late Jurassic geometries and ties to the Godwin wells, but also had benefits at Paleocene level. A comparison of the datasets is shown in Figure 4: Comparison of the seismic surveys, PGS MSP & CGG Cornerstone/Broadseis.

5 PROSPECTIVITY UPDATE

A map of the leads and prospects envisaged at the time of relinquishment is given in Figure 1: Map of remaining licence prospectivity. A summary of the associated volumes and risks and their evolution through time is given in Table 4: Prospectivity summary. The volumes and risks listed are the latest Q4 2014 internal peer review within Idemitsu, made as a precursor to the relinquishment decision. While some Upper Palaeocene leads are retained for completeness, the lack of AVO response downgrades their perceived prospectivity significantly. The main remaining prospectivity on block is at Upper Jurassic level within the Fulmar Formation interpod play. Secondary prospectivity at Upper Jurassic turbidite levels (Ribble/Freshney) and Rotliegend levels remains, but the risks are higher and volumes are smaller in these secondary targets.


Table 2: Seismic database

Figure 3: Seismic and well database


Figure 4: Comparison of the seismic surveys, PGS MSP & CGG Cornerstone/Broadseis

5.1 Eocene A top Tay amplitude map, derived from the PGS MegaSurvey Plus PSTM data, was used to delineate the Tay fairway, but no significant closures are evident in the licence area, and offset Tay sandstone discoveries all occur within such closures. Detailed rock physics analysis of key offset wells including the Gannet D 22/21-D7 well, 22/23c-3Z, 22/22b-2, 22/22b-4,22/22b-5 and 22/22c-6, gave no clear encouragement for a Tay HC accumulation on the licence, certainly within any closure, and on that basis Tay Sst prospectivity was not pursued further.

5.2 Upper Palaeocene Initial rock physics work was undertaken using the PGS MegaSurvey Plus PSTM data. Rock physics modelling of wells 22/16b-5 (see Figure 5: 22/16b-5 Logs) and 22/23b-1 was carried out to understand the AVO behaviour of Cromarty sandstone. Fluid replacement modelling was applied to the two wells, and offset well data and nearby field data were used to guide the fluid replacement parameters. Results suggested fluid effects should be evident within both the Cromarty and Forties sandstones, but weaker within Forties sandstone. AVO modelling was undertaken for both wells and suggested clear AVO responses should be evident in the oil case scenario, particularly for 22/16b-5. Learnings from the rock physics modelling were then applied to the inversion volumes, of P impedance, Vp/Vs and the “Hydrocarbon stack” attribute derived from these two parameters. Confidence in the method was obtained by noting positive correlation between “Hydrocarbon Stack” values and Forties oil accumulations at Arbroath, Montrose. Applying the same method to the Cromarty, (Figure 6: "Hydrocarbon Stack" as a Cromarty oil indicator, on PGS MSP data) only the leads Viti and Vanua show significant deviation from background trend, but even here there is no clear structural conformance, and it is difficult to say unambiguously that this is not a reservoir quality effect. Moreover, the responses at Biddenden are very subdued, with only slight deviation from background, and in the areas of Eglantine and Adgestone there is no response evident, so those latter two leads were downgraded.


Figure 5: 22/16b-5 Logs

Figure 6: "Hydrocarbon Stack" as a Cromarty oil indicator, on PGS MSP data


Further rock physics modelling and AVO analysis was completed when the CGG Cornerstone and Broadseis datasets were received. In terms of broad structural information the three datasets provide similar information, but the Broadseis has higher resolution and more high frequency information. It was apparent from this analysis that any AVO anomalies are even less prominent than for the PGS MegaSurvey Plus, including Viti and Vanua Leads (Figure 7: dBGT attribute Near Top Sele, CGG on Cornerstone and BroadSeis). On this basis, the Upper Palaeocene prospectivity on the licence was downgraded further, and focus shifted to the Late Jurassic.

Figure 7: dBGT attribute Near Top Sele, CGG on Cornerstone and BroadSeis data (CGG)

5.3 Chalk & Lower Cretaceous.

A low relief TWT structural nose with some small TWT “closure” exists at top chalk level on the licence (see Figure 1: Map of remaining licence prospectivity). Any good reservoir within the chalk would be expected to have some amplitude response but on the P1800 licence there is no such response to compare with anomalies in the Banff, Kyle, Curlew C, Acorn, Joanne, and Stella areas where chalk does produce. Similarly offset wells at 22/22a-1, 22/22b-4Z and 22/23b-1 give little cause for encouragement. Even if a chalk reservoir was present within the closure, the low structural relief means that commercial saturations are unlikely to be present. In that context, chalk prospectivity was not pursued further on the block. Similarly, there was insufficient encouragement from offset wells to pursue any Lower Cretaceous mass flow sand prospectivity within this time closure or elsewhere on the licence.

5.4 Late Jurassic The main remaining prospectivity on the licence is late Jurassic in age, and predominantly at Fulmar level. There are other non-Fulmar sands present in the area, which we refer to loosely as “Ribble sandstone” units. These are a series of thin sands present in the J54 to J64 interval within the licence area, mainly in the deeper more basinal parts of the West Central Graben. This includes wells 22/1-8, 22/22b-4, 22/22b-2, 22/23b-6, 22/23b-5. They are however thin when present, and on the intermediate “slope” areas between the Montrose-Arbroath high and the basin axis, a more restricted distribution or sediment bypass seems likely. Equivalent aged sandy sections are however present in more proximal locations to the Montrose Arbroath high also, such as in the Cayley and Godwin area (see wells 22/17-3 & 3X, 22/17-4, Figure 8: Jurassic well correlation interpod play) where


they can have minor HC saturations. The reservoir quality is however significantly reduced relative to the Fulmar (Figure 9: 22/17-4Z Fulmar & Ribble Petrophysics). For this reason the Ribble sands have been treated as an interesting secondary target, but unlikely to form an objective worth pursuing in their own right, at least within the licence area.

Figure 8: Jurassic well correlation interpod play

Figure 9: 22/17-4Z Fulmar & Ribble Petrophysics


The Late Jurassic interval has been mapped sub-regionally on the PGS MegaSurvey Plus PSTM and where feasible included picking of the BCU, Top Triassic/Skagerrak, Top Smith Bank, Top Zechstein, and Top Rotliegend. Figure 10: PGS MegaSurvey Plus arbitrary line, key Fulmar Targets shows the section of an arbitrary line between the main Jurassic prospect on the licence and nearby Fulmar analogue accumulations at Cayley, Godwin, Shaw and Wood. A fairly typical interpod character is evident. More detailed mapping has been undertaken on the more recent CGG Cornerstone and Broadseis data sets, including detailed well ties. The closest and most important well ties are with the Godwin wells 22/17-4 and 22/17-4Z (Figure 11: 22/17-4Z Godwin discovery well seismic tie) but critical well ties were also made at Jurassic levels with 22/17-3 & 3X (Cayley) & 22/22a-7Z (Shaw). The Top Smith Bank TWT map (variably the base Fulmar, Pentland and Skagerrak in the area) is shown in Figure 12: Syros-Godwin Smith Bank Pod morphology (TWT). A key feature is the extension of sealing ridges of Smith Bank “pods” extending out from the main Montrose Arbroath High. These appear to play a controlling role in the spill points of Shaw and Godwin, and a similar sealing mechanism is therefore invoked for Syros. The most critical feature is the Smith Bank “arm” extending between Syros and Godwin. Two depth conversion models were applied to the Late Jurassic, but there was little apparent GRV sensitivity to the model used. The base case uses a three layer model: i) MSL to BCU, ii) BCU to Top Fulmar, and iii) below Top Fulmar. The resulting Top Fulmar depth map is illustrated in Figure 13: Syros & Godwin Pressures and Top Fulmar Depth, with high and low case lowest closing contours (LCC). Pressure data and the inferred OWC for Godwin discovery are also shown. These appear to confirm that the Godwin contact must be controlled by a Smith Bank Pod “arm” similar to the trap concept invoked for Syros.

Figure 10: PGS MegaSurvey Plus arbitrary line, key Fulmar Targets (PGS MSP)

Encouragements for Fulmar reservoir presence were first received on the PGS MegaSurvey Plus amplitudes, and further inversion work on CGG Cornerstone seismic suggested well defined Fulmar reservoir “interpods” pinching out and laterally sealed between Godwin, Syros, Sicily, and Shaw (see Figure 14: Fulmar interpod definitions from Fulmar amplitude (PGS MSP) and impedance). The fault seal dependent Shawsgate lead is also apparent on these maps. Rock physics work based on the Godwin wells suggest that a threshold P impedance of < 9000 m/s*g/cc is a useful discriminator of Fulmar reservoir, but that it is difficult to distinguish


brine and HC fill. A P-impedance dip section (see Figure 15: Syros Impedance dip section) and an arbitrary line P-impedance section (Figure 16: Godwin-Syros Impedance arbitrary line section) illustrate the pinchout and separation by Smith Bank Pods of the Syros Prospect from Sicily lead and Godwin.

Figure 11: 22/17-4Z Godwin discovery well seismic tie, MS plus (PGS)

Figure 12: Syros-Godwin Smith Bank Pod morphology (TWT)


Figure 13: Syros & Godwin Pressures and Top Fulmar Depth

Figure 14: Fulmar interpod definitions from Fulmar amplitude (PGS MSP) and impedance (mainly CGG Cornerstone)


Figure 15: Syros Impedance dip section (Cornerstone data set basis - CGG)

Figure 16: Godwin-Syros Impedance arbitrary line section (Cornerstone data set basis - CGG)


On the basis of the various work programme analyses, Syros and Sicily have been risked similarly at 35%, with containment the critical risk (see Table 5: Summary of risks for remaining prospects/leads). Volumetric input parameters were taken from regional offset well data for the Fulmar, and Godwin and Cayley in particular. The Pmean recoverable oil volume for Syros is 19.2 mmbbl and for Sicily is 14.4 mmbbl (see Table 4: Prospectivity summary), but the shared risks mean a high amount of dependency between them – Sicily has a

very good chance of success if Syros works. P10 oil volumes for Syros and Sicily are 32.2 and 25.1 mmbbl

respectively making them an attractive combined target. After internal review, Syros was still considered an attractive target and approval to proceed was achieved, contingent on successful farm-down to share the risk. A notional well location, just off the P90 volume contour, was selected and scoping parameters for the notional well location are listed in Table 3: Notional Syros Well details. Sicily Prospect is essentially a very similar and smaller along strike equivalent of Syros. Shawsgate is an additional Fulmar lead, as shown in Figure 17: Dip section through "Shawsgate" Lead. It is more sizeable than Sicily (mean ~ 23 mmbbl), but has an element of fault seal required, and is therefore much riskier (Pg 15%). Other small structures at Fulmar level were identified in early evaluations of the licence, but are either too small or too risky for consideration in a commercial context. These structures are summarised in Table 4: Prospectivity summary and Table 5: Summary of risks for remaining prospects/leads.

Figure 17: Dip section through "Shawsgate" Lead (Cornerstone – CGG)

Table 3: Notional Syros Well details


5.5 Palaeozoic Charge into Palaeozoic reservoirs of the Zechstein and Rotliegend units is demonstrated by the small Carnoustie oil accumulation underneath Arbroath field, which produced from Zechstein limestone from 1994 until late 2013 (see Figure 1: Map of remaining licence prospectivity). The neighbouring 22/18-1 well also demonstrates the presence of good Rotliegend reservoirs (see Figure 3: Seismic and well database).

Figure 18: R1 Rotliegend Prospect seismic section (Cornerstone – CGG)

A tilted fault block at Rotliegend level with sufficient fault offset to allow juxtaposition against Late Jurassic source rocks (KCF and/or Heather Fm.) is recognised on the licence, and assigned the name “R1”. The crestal depth is ~ 4225 m TVDSS with a spill around 4375 m TVDSS, into another small fault block. If that also seals, spill could be up to 100 m deeper. A seismic section is shown in Figure 18: R1 Rotliegend Prospect seismic section. The resources and risks associated with both the Rotliegend prospects, and a possible Zechstein secondary reservoir similar to Carnoustie, are listed in Table 4: Prospectivity summary and Table 5: Summary of risks for remaining prospects/leads

6 FURTHER TECHNICAL WORK UNDERTAKEN

6.1 Basin modelling

Given the wealth of discoveries in the area, hydrocarbon charge was not perceived as a key risk. An effort was however made to understand the likelihood of an oil versus a gas accumulation at Syros, and the other P1800 prospects. To this end 2D basin modelling was undertaken. Results suggested a predominance of oil generation over gas, with an onset of oil generation around 55Ma, and a peak in deeper parts of the kitchen area at around 30 Ma (later ~ 20 Ma in shallower kitchen areas). 2D modelling also illustrated a lack of connectivity between the main gas kitchen and the P1800 Jurassic prospects – suggesting any remaining gas accumulations are likely to be limited to the deeper graben flanks, and that in the P1800 area oil accumulations should predominate.

7 RESOURCE AND RISK SUMMARY

Figure 1: Map of remaining licence prospectivity illustrates Idemitsu’s view of the key remaining prospects and leads on the licence. Table 4: Prospectivity summary lists the associated volumes, and Table 5: Summary of risks for remaining prospects/leads lists the associated risks.


Table 4: Prospectivity summary


It remains Idemitsu’s view that Syros Fulmar prospect, with a P50 recoverable volume of ~ 17 mmbbl and ~7bcf, and a P10 recoverable volume of ~32 mmbbl and ~16 bcf, remains the most attractive prospect on the block, assigned a chance of geological success of 35%. The mean resource is ~ 19 mmbbl and ~ 10 bcf, i.e. ~ 21 mmboe. Furthermore, there is a strong positive dependency in a success case at Syros for additional resource at Sicily prospect. This represents a further ~12mmbbl in the P50 case and ~25 mmbbl for the P10 (~14 mmbbl for the mean). Prospectivity remains at Rotliegend and Zechstein level (R1), but the Zechstein would be very small (3 mmboe at P50 level). For the Rotliegend it is better, at ~ 11 mmboe, and it looks more favourable at P10 level (~39 mmboe). We assign R1 a chance of geological success of 20%, but in commercial terms any attempt to exploit it would be difficult to justify without a short tie back to an existing accumulation.

Table 5: Summary of risks for remaining prospects/leads

8 CONCLUSIONS

A detailed work programme undertaken by Idemitsu on the P1800 licence has fulfilled all commitments made during the 26th Round application. Evaluation of all prospective stratigraphic levels on the licence leaves remaining prospectivity at Paleocene, Jurassic, and Permian levels. The rock physics work undertaken has however downgraded the Paleocene prospectivity such that it now has either very small or very high risk prospects. The work did not support HC fluid accumulations in the larger Cromarty pinch-out prospects. Similarly, there remains prospectivity within a small to moderate sized fault block (R1) at Rotliegend sandstone and Zechstein carbonate level, but without other accumulations on the licence, the commerciality looks weak. The work programme has however been encouraging for the Syros prospect and its smaller lookalike, the Sicily prospect, at Fulmar level within the Late Jurassic. Both are similar in nature and assigned a Pg of 35%. Syros has a mean resource of just under 21 mmboe (19.2 mmbbl, 9.6 bcf), and if successful it is difficult to imagine Sicily prospect, with a further 14 mmbbl, not also being successful. Together they give a combined mean recoverable resource of ~ 35 mmboe. Attempts to farm-down within the licence time frame were however unsuccessful, leading to eventual relinquishment.


9 CLEARANCE

Permissions for the publication of seismic data have been sought and granted, with our thanks, from PGS for their MegaSurvey Plus data, and from CGG for their Cornerstone and Broadband data.

10 ABBREVIATIONS USED

AVO: Amplitude versus Offset BCU: Base Cretaceous Unconformity CNS: Central North Sea dBGT: deviation from Background Trend Fm: Formation IPUK: Idemitsu Petroleum UK KCF: Kimmeridge Clay Formation LCC: Lowest closing contour MAH: Montrose Arbroath High MS: PGS MegaSurvey MSP: PGS MegaSurvey Plus MSL: Mean sea level Pg: Chance of geological success UKCS: UK continental shelf WCG: West Central Graben

11 CONTACT DETAILS

Parties interested in future co-operation in the area can contact Idemitsu directly:

6th Floor Shaftesbury House 151 Shaftesbury Avenue London WC2H 8AL Tel – Switchboard +44 (0) 20 7395 6140 CNS Team Leader: email – [email protected]

mailto:[email protected]

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