Cliff Head Oil Field- Update and Future Plans

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16 January 2002

ROC is pleased to make the following release for and on behalf of the WA 286 P joint venture.


  • Preliminary in-place oil calculations suggest that the recently discovered Cliff Head Oil Field (“The Field”) in the offshore Perth Basin, Western Australia, (Attachment 1) has the capacity to contain between 80 and 100 million barrels of oil in place (“MMBOIP”).
  • A satellite structure, which may prove to be part of the Field, and located immediately to the north of it, is estimated to have a further 20 to 30 MMBOIP potential (Attachments 2, 3 and 4).
  • The Joint Venture is awaiting the full results of crude oil analysis and therefore it is too early to calculate specific recovery factors for the Field. However, if, as seems likely, the 31.6º API oil is analogous to other crudes in the fields in the onshore Perth Basin then the recovery factor could range from 25% to more than 35%; implying recoverable oil reserves of 20 MMBO to more than 35 MMBO based on primary recovery from the Cliff Head structure.
  • The recently drilled Cliff Head-1 discovery well and the successful appraisal well, Cliff Head-2, confirmed the presence of reasonable to excellent reservoir quality sandstones; a minimum gross oil column of 28.5 metres and a net to gross ratio between 60% and 65%. Reservoir porosities up to 28% were encountered in the net reservoir section at Cliff Head1 and average net reservoir porosities of 23% and 18% have been calculated for Cliff Head-1 and Cliff Head-2 respectively. These porosities are equivalent to the porosities in many of the prolific fields on the North West Shelf. The wells also established a common oil-water contact over the 1.1 km distance between the two bottom hole locations and confirmed the reliability of the pre-drill seismic interpretation in the immediate vicinity of the Field.
  • The discovery has significantly upgraded the hydrocarbon potential of the offshore Perth Basin, particularly since a number of undrilled prospects of significant size are recognised in the immediate vicinity of, and on trend from, the discovery well.
  • The commercial potential of the Cliff Head Oil Field and immediately surrounding area, is further enhanced by its near shore, shallow water, location; proximity to shore-based infrastructure; the relatively shallow depth of the reservoir (approximately 1,250 metres) and the fact that the geological conditions and modern drilling techniques allow for cost efficient drilling operations.
  • As a matter of urgency the WA-286-P Joint Venture intends to further appraise the Cliff Head discovery and further explore the area. Subject to finalizing logistical and operational details the Joint Venture anticipates that the forward strategy for Cliff Head and the surrounding area will include the drilling of several back-to-back wells representing a mix of exploration, appraisal and, if warranted, development wells. The Joint Venture wants to restart the drilling programme as soon as possible after completing a thorough evaluation of the recently obtained data and accessing a suitable rig slot. The current expectation is that the next round of drilling will probably commence sometime between May 2002 and January 2003 with the exact timing being determined by rig availability and weather conditions.


Drilling operations at Cliff Head-1 and Cliff Head-2 commenced on 25 December 2001 and were successfully completed 11 days later on 4 January 2002. The wells were drilled by the Ensco 56 jack up rig in 16 metres of water, 11 kilometres offshore Dongara, Western Australia.

(Attachments 1 and 2). A total of 3090 metres of section was drilled: 1499 metres to total depth in Cliff Head-1 and 1591 metres from the side track kick off point of 429 metres to total depth of 2020 metres in Cliff Head-2. The bottom hole location of Cliff Head-2, drilled at a 60º angle from the Cliff Head-1 location, is 1.1 km north northeast of the vertically drilled Cliff Head-1 (Attachments 3 and 4). Drilling and towing operations were accomplished within budget and with no safety or environmental incidents.

The WA-286-P Joint Venture’s stated initial intention was to drill one well at the Cliff Head location for a budgeted cost of A$10.3 million. The success of Cliff Head-1 and the efficient drilling and towing operations, encouraged the Joint Venture to immediately drill Cliff Head-2 as a side-track appraisal well. The preliminary final total cost of the two well program, including the rig tow, is approximately A$8.7 million, some 15% less than the budget for the original one well programme.


Cliff Head-1 is a regionally significant discovery which is believed to represent a number of “firsts”, both for the offshore Perth Basin and the broader Australian oil industry. Specifically it is:

ƒ* The, first potentially commercial, live oil discovery in the northern part of the offshore Perth Basin.

  • The first unequivocal demonstration that there is a working petroleum system in this part of the offshore Perth Basin, capable of generating and entrapping significant quantities of oil.
  • The first time that an oil field offshore Australia has been discovered and successfully appraised within 11 days of the commencement of the discovery well.
  • The first potentially commercial oil discovery offshore Australia which is majority owned by five small, publicly-listed, Australian oil companies – and the first time that such a field has been operated by one such company rather by than a multi-national oil company or one of the three big Australian oil companies.


The WA-286-P Joint Venture is comprised of:

  • Roc Oil (WA) Pty Ltd (Operator - 30.0%
  • AWE Oil (Western Australia) Pty Ltd - 27.5%
  • Wandoo Petroleum Pty Ltd - 25.0%
  • ARC Energy NL - 7.5%
  • Voyager Energy Limited - 5.0%
  • Westranch Holdings Pty Ltd - 5.0%, (a subsidiary of Norwest Energy NL)


Commenting on the recent events at Cliff Head, ROC’s CEO Dr John Doran stated that:

“Cliff Head-1 provided the Joint Venture with a nice Christmas present the true value of which will gradually become more obvious as it is unwrapped during the next 12-18 months.

Immediately after an oil discovery and a successful appraisal well everybody wants to know what is going to happen next - and when. In this regard, it is sometimes hard to strike the right balance between the genuine enthusiasm created by the drill bit and natural desire not to inadvertently overstate the discovery’s ultimate commercial potential. Perhaps, it is sufficient to say that, on the evidence gathered to date, the Joint Venture would consider itself to be extremely unlucky not to have cause to proceed with a commercial development of the Cliff Head Field and/or a nearby future discovery.

From ROC’s specific corporate perspective:

ROC now regards WA-286-P as a newly established core area. ROC fully expects to exercise, at the maximum (20%) level, its option to acquire from AWE Oil (Western Australia) Pty Ltd equity in TP/15 as outlined in ROC’s ASX Release dated 7th September 1999. The rationale behind the exercise of the option reflects the fact that TP/15 contains a number of discrete undrilled prospects and leads on direct geological trend from the Cliff Head Oil Field as well as portions of some undrilled prospects that are located on the boundary between the two permits.

We are pleased that the first two wells drilled by ROC in Australia both found oil. For more than a year ROC has been looking for what it has described as “the next big thing”, initially on the assumption that it would take the form of an asset or corporate acquisition. Increasingly during 2001, we stated that if the overheated state of the acquisition market prohibited ROC from acquiring “the next big thing” at end 2001 we would consider redirecting our discretionary funds inwards towards organic growth targets, subject to the drilling results achieved during the year. Now, as we look back over 2001, we see that every one of ROC’s seven significant wells which commenced drilling during the year found hydrocarbons with the “worse” result being a 9 metre gas column in the Courbine-1 rank wildcat well in deepwater offshore Mauritania. All the other significant wells drilled by ROC found substantial commercial, or potentially commercial, hydrocarbons including two new rank wildcat exploration successes: the Chinguetti discovery offshore Mauritania and the Cliff Head Oil Field, offshore Perth Basin. As a consequence, the Company has decided to freeze most, but not quite all, of its new venture activity for at least several months - longer if need be - in order to ensure that it is well placed to work with its relevant joint venturers to realise the full value of its recently enlarged portfolio of undeveloped oil fields”.

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