Exploration Drilling Update

Roc Oil Company Limited 05 May 2006 5 May 2006 ROC OIL COMPANY LIMITED ('ROC') STOCK EXCHANGE RELEASE EXPLORATION DRILLING UPDATE: WEI-6-12S-1 WELL, OFFSHORE CHINA Wei-6-12S-1, Block 22/12, Beibu Gulf, Offshore China (ROC: 40% & Operator) As at 0600 hours (local time) on 5 May 2006, the Wei-6-12S-1 exploration well had drilled to a depth of 2,007 metres below rotary table ('mBRT') and the current operation was running in hole to drill ahead following a short wiper trip. At 1,956 mBRT, a sand with an apparent drilled thickness of three to five metres was encountered with good reservoir characteristics, strong oil shows and an associated increase in wet gas readings. Pre-drill interpretation suggests that this sand is at the top of an interbedded sand-shale sequence that is expected to be several hundred metres thick. At approximately 1,985 mBRT a sandy interval, with an apparent drilled thickness of about 16 metres, was encountered without any obvious oil shows but with very high wet gas readings. Until the well has been drilled to the proposed Total Depth of 2,530 mBRT and a full suite of electric logs acquired and analysed, it is not possible to comment as to the commercial significance of the hydrocarbon shows encountered to date. The Wei-6-12S prospect represents an unusual structural target. Within a small (about one sq km) area of closure lies a thick (hundreds of metres) gross prospective sedimentary sequence which together creates a potential trap capacity in the order of a few to many tens of millions of barrels of oil. Information from wells within and adjacent to Block 22/12 suggests that: reservoir quality will be good to excellent; the hydrocarbon type is likely to be oil rather than gas; recovery factors should be high; and oil viscosity is unlikely to be a problem in the targeted reservoir section. Wei-6-12S-1 is positioned so as to test the structure some 20 to 30 metres below its crest. The well is in about 30 metres of water, approximately 3 km southwest of the 2002 Wei-6-12-1 oil discovery. Commenting on the well results to date ROC's CEO, John Doran, stated that: 'On the basis of currently available drill data the well is likely to be classified as a discovery. While that is technically encouraging, it is not the key commercial point. The real question the well needs to answer is whether or not the accumulation is large enough to merit further appraisal and we won't have the first part of that answer until early next week.' The Block 22/12 Joint Venture comprises: Roc Oil (China) Company 40% and Operator Horizon Oil Limited 30% Petsec Energy Ltd 25% Oil Australia Pty Ltd* 5% * subsidiary of First Australian Resources Michelle Manook For further information please contact: General Manager - Corporate Affairs Dr John Doran on Tel: +61-2-8356-2000 Fax: +61-2-9380-2635 Email: jdoran@rocoil.com.au Or visit ROC's website: www.rocoil.com.au Dr Kevin Hird General Manager Business Development Tel: +44 (0)207 586 7935 Fax: +44 (0)207 722 3919 Email: khird@rocoil.com.au Nick Lambert Bell Pottinger Corporate & Financial Tel: +44 (0)207 861 3232 This information is provided by RNS The company news service from the London Stock Exchange
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