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License P. 1292, Block 15/11a Relinquishment Report January 2009 _____________________________________________________________________________________________ 1. General Licence: Round: License Type: Blocks: Equity: P.1292 23rd (2005) Traditional 15/11a Talisman (operator) Work Programme: Pre-stack depth migration; 25km2 output area from 120km2 input area. There are no outstanding work commitments for this Block. 100% 2. Licence History 0o 12’W 0o 00’E 0o 12’E Key Field 58o 40’N 14/14b 14/15b 15/11b Discovery Prospect 0 2 4 km 14/15a 15/13b 14/14a P. 1292 15/12b CLAYMORE 15/13a 58o 30’N 15/16b 15/17 PIPER 15/18b Lowlander SCAPA SALTIRE HIGHLANDER TARTAN Iona CHANTER DUART 58o 20’N 15/18a 14/19s 14/20b PETRONELLA Figure 1: Location Map of Licence P. 1292, Block 15/11a. Block 15/11 was first awarded in 1972 to an Occidental-led group as part of the 4th Round multi-Block licence P.220; it was first drilled later that year when 15/11-1 targeted a large four-way dip closure but was abandoned dry. Well 15/11-2, drilled in 1973, was also abandoned as a dry hole. In 1974, the third well on the block, 15/113, was abandoned dry but encountered good oil shows in the primary Piper target. This well also found heavy (10o API) oil in shallow Tertiary sands (2200-2800ft TVDss). Following the discovery of the Piper and Claymore Fields, the Block was transferred initially to Segregation Licence P.247 in 1974 and then into Segregation 1 License P. 1292, Block 15/11a Relinquishment Report January 2009 _____________________________________________________________________________________________ Licence P.248 and finally P.250, both in 1976. The Block was partially relinquished at the end of the initial term in 1978. Elf-Enterprise-Caledonia (EEC), which had replaced Occidental as the operator in the UKCS following the Piper Alpha disaster in 1988, drilled well 15/11a-4 in 1990. The well encountered hydrocarbon shows. The relinquished part of the block, 15/11b, was awarded in the 16th Round in 1995 to an Enterprise-led group; in 1996 they drilled 15/11b-5 which was again abandoned with oil shows. Block 15/11b was relinquished in 2001 and Block 15/11a in 2004. Block 15/11 was contested in the 23rd Round in 2005 with Block 15/11a being awarded to Talisman 100% as a Traditional Licence, and Block 15/11b as a Promote Licence to Iceni (100%). In 2007, Iceni was acquired by Bridge who went on to drill the 15/11b-6 well in 2008; this well failed to encounter hydrocarbons and was abandoned dry. During 2007-8, Talisman attempted to farm-down their interest in Block 15/11a in order to get a full or partial carry on a well to test the Deep Colonsay prospect. Having failed to secure a partner, and unwilling to drill the prospect at 100% equity, Block 15/11b was surrendered on November 3, 2008. 3. Exploration Activities No new wells were drilled within Block 15/11a during the licence period. The wells already drilled within the surrounding area are: 15/11-1 15/11-2 15/11-3 15/11a-4 15/11b-5 15/11b-6 Occidental Occidental Occidental EEC Enterprise Bridge 1972 1973 1974 1990 1996 2008 P&A Dry P&A Dry P&A Oil Shows P&A Oil Shows P&A Oil Shows P&A Dry In 2001, Talisman acquired a proprietary 3D seismic survey over all of their acreage in the Flotta Catchment Area (FCA) which included Block 15/11a. This was processed at the time using a full Kirchoff pre-stack time migration. In 2006, Talisman initiated a pre-stack depth migration of the full 3D dataset; numerous delays meant that the output data were not delivered to Talisman until March 2008. 4. Prospectivity Analysis 4.1 Upper Jurassic Piper Fm The only prospectivity recognised by Talisman at the time of application for Block 15/11a was a four-way dip closure reservoired in Upper Jurassic Piper sandstones, informally known as Deep Colonsay (Figure 2). Seismic mapping on the latest PreSDM dataset shows a structural closure down to at least 6400ft; well 15/11-3, drilled within this four-way dip closure and penetrating top reservoir at 6110ft, exhibits evidence of both live oil and tarry globular oil from sidewall core analysis with residual saturations up to 30%. Talisman interpret these data as evidence of a former hydrocarbon column which has subsequently been breached, at least partially. The presence of the Deep Colonsay prospect relies on this breaching occurring discretely along the fault which separates 15/11-3 from the crest of the mapped structure at c. 5700ft. This would give a potential unbreached residual column of 300ft to the east of the fault. 2 License P. 1292, Block 15/11a Relinquishment Report January 2009 _____________________________________________________________________________________________ 0o 00’E 0o 02’E 0o 04’E 0o 06’E o 58 32’N 2 0o 08’E Zechstein faults projected up onto BCU surface Complete erosion of Piper reservoir at BCU surface 58o 31’N Piper Sa o 58 30’N nd sto ne er 0 ed 1 km Se is m ic Li ne od Figure 2: Top Piper Sandstone Reservoir Depth Structure The shallow marine Piper-Sgiath sandstones are proven to be of excellent quality in all three of the surrounding wells. In wells 15/11-1 and 15/11-3, the reservoir section is thinned due to erosion by the Base Cretaceous unconformity (BCU). Over the crest of the Deep Colonsay prospect, the seismic reservoir package is interpreted to thicken to more than 400ft (Figure 3). The reservoir properties are expected to be similar to the adjacent wells with high net to gross and porosities in excess of 20% for the upper sand section. 15/11-2 SW Deep Colonsay NE 5000 ft Top Chalk BCU / Top Piper 7500 ft MCU / Base Piper Zechstein Figure 3: Top Deep Colonsay Seismic Illustration 3 License P. 1292, Block 15/11a Relinquishment Report January 2009 _____________________________________________________________________________________________ The Kimmeridge Clay Formation, which provides the topseal to most of the Upper Jurassic Fields and discoveries in the Witch Ground Graben, is absent over the crest of the Deep Colonsay prospect, as evidenced by wells 15/11-1 and 15/11-3. Instead, the top seal relies on Upper Cretaceous chalks and marls. The viability of this top seal has been proven over the crest of the nearby Piper Field and in the Hood discovery in Block 15/13a. 4.2 Tertiary Columns of viscous, heavy oil (10o API, 4089 cP) have been encountered in Eocene sands in 15/11-3 and a number of wells adjacent to Block 15/11a at depths of around 2000-3000 ft TVDss; well 14/15-2 drillstem-tested one of these intervals and managed to recover 3 bbl of oil to surface at an estimated rate of 10 stb/d. Despite oil-in-place estimates of 500-1000 mmstb, these are not considered by Talisman to be commercially viable at present due to the adverse nature of the fluids. 5. Reserves Summary Mean P90 P50 P10 STOIIP (mmbbls) 37 5 22 90 Reserves (mmbbls) 20 3 12 49 Talisman’s internal Peer Review process assigned a 25% geological chance of success to the Deep Colonsay prospect. Whilst this is not an unreasonable level of risk per se, it is almost entirely due to one factor, preservation of the hydrocarbon trap, and is therefore considered to be unacceptable. 6. Clearance Talisman Energy (UK) Limited, as the former operator of Block 15/11a, confirms that the seismic data contained within this report and the interpretation thereof are proprietary to Talisman and give permission to publish the report. 4