Rockpool Acqui Regulatory News (ROC)

25 Feb 2005 07:01

Roc Oil Company Limited25 February 2005 25 February 2005 ROC OIL COMPANY LIMITED ("ROC") STOCK EXCHANGE RELEASE DRILLING ACTIVITY UPDATE: CLIFF HEAD - 5 KEY POINT • Cliff Head-5 (CH-5), a vertical, "pathfinder", appraisal well in the Cliff Head Oil Field, offshore Western Australia, is being plugged and abandoned after encountering the top of the reservoir target 56 metres low to prognosis and coincident with the field's oil-water contact. The Ensco 56 rig will now move to drill the next well in the programme, Cliff Head-6 (CH-6), approximately 2.3 km northwest of the CH-5 location. Roc Oil (WA) Pty Ltd, as Operator of the WA-286-P Joint Venture (the "JointVenture"), advises that the CH-5 appraisal well has reached a Total Depth of1,516 metres and completed wireline logging. As of 0600 hours on Friday 25February (Australian Western Standard Time) the current operation was preparingto plug and abandon the well prior to the rig moving approximately 2.3 km to thenorthwest to drill CH-6, the second well in the planned two well programme. CH-5 is a vertical "pathfinder" appraisal well located about 1 km southeast ofthe CH-1 discovery well. The primary purpose of CH-5 was to determine the natureand extent of the reservoir in the East Ridge portion of the Cliff Headstructure which had not previously been drilled. The well encountered the top ofthe main reservoir target sand 56 metres low to prediction and coincident withthe field's oil-water contact. The discrepancy between the prognosed and actualdepth at top reservoir target level is currently interpreted to be mainly due tounexpected seismic velocity variations in the overlying sequence in that part ofthe field. The reservoir quality of the target sand sequence drilled by CH-5 isthe best yet encountered in the Cliff Head area. The results of CH-5 indicate that the depth configuration of the field at topreservoir level needs to be refined in the light of additional subsurface datapoints and with particular reference to the seismic velocity variations. Thiswork is currently underway. Until the work has been completed, during March2005, it is not possible to make any definitive statement about the impact whichthe CH-5 well has had on field reserves. Directionally, however, it would seemthat proved and probable recoverable oil reserves at Cliff Head may be reducedby a few to several millions of barrels of oil ("MMBO") from the previouslyquoted range of 18 to 21 MMBO. It is possible that the addition of the newvelocity variation information to the field database will cause other parts ofthe structure, which are currently mapped as being below the oil-water contact,to be remapped as being above that contact. Whether or not this will prove to bethe case will not been known until after the drilling of CH-6 which should becomplete in early March 2005. A Final Investment Decision will also wait uponthe results of CH-6. Commenting on the results from CH-5, Dr John Doran, ROC's Chief ExecutiveOfficer, stated that: "Fifty-six metres is a big seismic bust, particularly at relatively shallowdepth. Seismic velocity variations of this magnitude can work against you - asthey have plainly done at the CH-5 location - or, they can work for you, ascould happen in other parts of the structure. However, whether or not that willhappen elsewhere within the Cliff Head field is pure speculation at this stage.The fact that the target reservoir sands in CH-5 represent the best qualitysands seen in the field area offers a degree of ironic comfort." The WA-286-P Joint Venture comprises: Equity Roc Oil (WA) Pty Ltd (Operator)...................37.5% AWE Oil (Western Australia) Pty Ltd...............27.5% Wandoo Petroleum Pty Ltd..........................24.0% Voyager (PB) Limited...............................6.0% CIECO Exploration and Production (Australia) Pty Ltd................................5.0% Bruce ClementChief Operating Officer For further information please contact: Dr John Doran 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