Blocks 28/9 & 28/10c Greater Catcher Area (Licence P1430)
(Nautical 15%)

This Traditional Licence is located on the West Central Platform, west of the Central Graben and the nearby Bittern Field. Regional and block specific evaluation was originally carried out with EnCore prior to application and successful award in the 24th Seaward Licensing Round.

The blocks contain the Catcher discovery in the Palaeocene (Cromarty Sandstone) and the Catcher East, Varadero and Burgman discoveries in the Eocene (Tay Sandstone). Mapping has demonstrated several similar and robust undrilled prospects at both stratigraphic levels.

The initial Catcher discovery by well 28/09-1 (and sidetrack 28/09-1Y) and the Catcher East discovery by well 28/09-1Z, during the summer of 2010, heralded one of the largest discoveries on the UKCS in the last decade. 2 further exploration wells at Varadero and Burgman and an appraisal well at Catcher North followed and successfully encountered additional resources in late 2010 and early 2011.

The Varadero exploration well, 28/09-2, some 4km west of the Catcher discovery was drilled in December 2010 to a total measured depth of 5,205 feet having successfully encountered high quality oil bearing reservoir within the target Tay Sandstone. The formation had a gross thickness of 186 feet with a calculated net pay of 84 feet, significantly better than prognosed. Analysis of the logs indicates the reservoir quality is excellent, with high permeability, average porosity of 35% and average oil saturation
of 84%. In addition to the primary interval there is a further 22 feet of net hydrocarbon pay in thinner sands. Wireline logging and pressure testing has been carried out which indicate that the reservoir fluids are oil with an API of approximately 26°. The well also encountered deeper sands of Cromarty age (the principal reservoir in Catcher) although, as expected, they were not hydrocarbon bearing at the Varadero location.

During January 2011, the Catcher North appraisal well 28/09-3 was drilled c.2.5km north of the Catcher wells to a total measured depth of 5,265 feet. The well encountered gas in the Tay Sandstone and oil in the Cromarty sandstone. Pressure data suggests that the Catcher North oil discovery is part of the Catcher and Catcher East accumulation. In support of this, the calculated oil-water contact within the Cromarty Sandstone section is consistent with that established with the Catcher discovery wells 28/09-1 and -1Y. The reservoir development at this location was towards the lower end of expectations, encountering 20 feet net pay within the Tay Sandstone, and 14 feet net pay within the Cromarty Sandstone. However
reservoir quality was excellent with an average porosity of 31% in both reservoirs.

The Burgman well, 28/09-4, was spudded on 1 March 2011 on a hanging wall structure situated 7km to the west and updip of Catcher and some 5km south of Varadero. The near vertical well trajectory for the Burgman 28/9-4 well was designed to test 3 targets in the Tay, Cromarty and Jurassic Sandstones and the well reached a total depth of 5,990 feet. The well encountered 2 sands in the Tay Formation, the Upper Tay Sandstone was 12 feet thick and gas bearing whilst the Lower Tay Sandstone was 10 feet thick and contained 24.3° API oil. Analysis of pressure data indicates that the combined formations have a gas-oil contact at 3,560 feet true vertical depth subsea (TVDss) and an oil water contact at 3,980 feet TVDss giving a gas column of at least 78 feet and an oil column of 420 feet. This indicates that the Lower Tay Sandstone, which is represented by high seismic amplitudes throughout the Burgman prospect, lies within the oil leg. Whilst good quality Cromarty and Jurassic Sandstones where encountered, they were water bearing.

The original 28/09-4 well path was not optimised to test the very high amplitudes within the Tay Formation and so the well was sidetracked some 1,641 feet to the southeast of 28/09-4Z to encounter a prognosed thicker section. The well was drilled to a total measured depth of 5,237 feet. The sidetrack successfully encountered a true vertical reservoir section of 64 feet net oil pay with an average porosity of 38% and an average oil saturation of 95%, significantly better than in the original Burgman well.

The success of this recent drilling campaign underlines the great potential of Block 28/9, with sands of thicknesses and quality often surpassing the pre-drill estimates. Oil bearing Cromarty Sandstones were not encountered at Burgman and appear to be limited to the Catcher area. However, the seismic data can confidently predict the presence of high quality hydrocarbon bearing Tay Sandstones, proven by the Catcher East, Varadero and Burgman discoveries. This augurs well for the numerous mapped anomalies on the block and a further exploration well is planned in Q1 2012 to test the Carnaby prospect located about 2km to the west of Burgman on the footwall of the major dividing fault.

The four oil discoveries have proven Block 28/9 to be one of the most prolific on the UKCS in recent times. Field development studies are well under way towards submitting a Field Development Plan to the Government in 2012 with a view to achieving first oil in 2015. Gross best estimate total contingent resources are estimated to be 155 mmbo (23 mmbo net) with significant exploration upside remaining on the block.