P1794 Relinquishment Document Blocks 22/2d, 22/3c & 22/4c

Transcription

1 P1794 Relinquishment Document Blocks 22/2d, 22/3c & 22/4c 1. Licence Information Licence Number: P1794 Licence Round: 26 th Round- Awarded January 2011 Licence Type: Traditional; (Drill or Drop within two years) Block Numbers: 22/2d, 22/3c & 22/4c Operator: Maersk Oil North Sea UK Limited 35% Partners: Eon Ruhrgas 35% and Venture North Sea Oil Ltd 30% 2. Synopsis Licence P1794 has been relinquished. All firm commitments have been met and the opportunities outlined in the application document were fully evaluated. However, it was not possible to mature a drillable prospect and a decision was made to relinquish the licence at the end of the two year drill-or-drop period. 3. Exploration Activity Licence P1794 is located in the Fisher Bank Basin, northern Quad 22. See Figure 1. The application for the blocks comprised a portfolio of Upper Jurassic and Lower Cretaceous prospectivity. Structural traps with Fulmar sands and stratigraphic traps with Punt Formation sands were identified The work programme included the reprocessing of c km 2 of existing long offset Cornerstone seismic data, covering the primary Jurassic and Cretaceous prospectivity, to PSTM and 1064 km 2 to PSDM. Seismic interpretation on the newly reprocessed data was followed by attribute analysis and frequency based attribute analysis and inversion. It was hoped that this would expose further prospectivity at shallower levels within the basin. New petrophysical interpretations were performed on a set of 33 key wells in and around the basin. Log data from seabed to TD for all wells was reinterpreted to assess any opportunities for missed pay and to collect offset data for reservoir parameter input ranges in the key levels of stratigraphy. Studies in the form of renewed sedimentology, biostratigraphic and chemostratigraphic analysis were initiated and completed in house and by external contractors. An external contractor undertook a project with direction from Maersk to assess the capability of the prospect controlling faults to seal against the basin margins and in places where Fulmar sands would be juxtaposed against other Fulmar sands and the underlying Pentland Formation. As part of this piece of work the same contractor carried out an independent validation of the structural interpretation across the licence. The prospects and leads characterized in the application document were evaluated and matured so as to make a recommendation as to whether or not to proceed towards drilling one or more parts of the portfolio within two years of the award date. Any well proposed would drill to the top of the Fulmar Formation or to 17,100ft TVDSS.

2 4. Prospectivity Analysis The primary prospect identified for the 26 th Round application was in the Upper Jurassic, Fulmar sands. This prospect Mordacus Deep is structurally segmented and divided into two parts; West and East. See Figure 2. The trap style is structural, both segments are fault closed at their crests and dip closed to the north. The seals are the overlying Heather and Kimmeridge Clay. The Western segment relies on cross fault sealing by the Rattray Volcanics on its western edge. The source rocks are the Upper Jurassic Kimmeridge Clay, the Heather Formation as well as the Middle Jurassic Pentland Formation. This Upper Jurassic Fulmar Play is proven in the Fisher Bank Basin by the well 22/2-2, drilled in 1983 by Burmah Oil Exploration Ltd. This well encountered 40 ft of Gas Condensate bearing Fulmar sand. Two exploration wells would be required to test the prospectivity identified and evaluate the resource estimates. Mordacus Deep West has a Pg of 26% and Mordacus Deep East has a Pg of 35% with Reserves estimates as tabulated in Table 1. Figure 4 illustrates the primary risk on these Jurassic prospects as Seal. There is a chance that the western prospect will not seal against the Rattray Volcanics along the basin margin faults. There is also a possibility that the fault segmenting the larger prospect into West and Eastern segments may not seal. This severely restricts the column length on the eastern segment which limits the volume range drastically when the two are rolled together. A secondary target was identified for the application in the 26 th Round. This was in the earliest Cretaceous Punt Formation. The Fisher Bank Basin is situated at the junction of the end of the Play Fairway for both the Scapa and Punt trends where they exit the Witch Ground Graben and the South Halibut Basin. This large basin was a topographic low at end Jurassic time and so it should have provided accommodation space for the distal, long distance transported elements of those sediment delivery systems. There is also scope for local sourcing from the Jaeren High, the Forties Montrose High, the Andrew Diapir and the Fladen Ground Spur. The 22/2-2 well encountered two very thin (5ft) porous sands in the Valanginian section, just above the top of the Kimmeridge Clay. This well is drilled on a local high, it was modeled for the purposes of the Mordacus LK prospect that the section might thicken down-dip off the crest of the Mordacus structure. Mordacus LK has an element of four way closure but can be maximized to its P1 area through stratigraphic pinch out and down dip extent. See Figure 3. Mordacus LK has a Pg of 29% and a resource range as tabulated in Table 2.

3 5. Reserves Summary Table 1 Mordacus Deep P50 Gas (bcf) P50 Condensate (mmboe) GIIP Resources Table 2 Mordacus Lower Cretaceous P50 Gas (bcf) P50 Condensate (mmboe) GIIP Resources Maps and Figures

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5 Figure 4: Strike section through Mordacus Deep West to East Showing the side seal issue to the west along the basin margin and the possible cross fault sand-sand juxtaposition between Mordacus Deep West and East. 7. Clearance Partners have reviewed this document and verified that DECC is free to publish it.