The field will be developed for production, subject to final government approvals, and first oil is expected to flow within 12 months.

Initial production rates will be in excess of 10,000 bopd through facilities with 15,000 bopd design capacity, operator Roc Oil said this morning.

“Proven and probable field reserves, in the fully appraised part of the Cliff Head structure, are currently estimated to be about 14 million barrels,” Roc said.

Before the drilling of Cliff Head-5, field reserves estimates were about 18 to 21 million barrels. But the disappointing results from that well have led to a significant downward revision.

However, Roc said there were upside reserve potential in areas adjacent to the field that were currently undrilled but which would be accessible from the production platform.

The total development cost is expected to be A$227 million. It will have four main components – an offshore platform, pipelines and umbilicals, onshore processing plant and drilling.

The small, normally unmanned, offshore platform will be in 18 metres of water, 11km from the coast and 14km from an onshore processing plant at Arrowsmith.

It will have seven active wells – five oil producers and two water injectors. The platform will also have two spare slots to allow for the drilling of additional wells in the future. The first of the five oil producing wells, Cliff Head-6, was drilled to total depth and is now being suspended for future production.

Two 14km 250mm pipelines, plus umbilicals, will link the platform to the onshore processing plant. One pipeline will transport oil from the platform to the plant. The other will transport water for water injection from the plant to the platform. To minimise disturbances to the local environment, the pipelines and umbilicals will be installed by using directional drilling techniques under the beach.

A processing plant will be constructed at Arrowsmith on an existing site formerly occupied by a lime plant. This facility will provide crude oil stabilisation and separation facilities, as well as water injection facilities. The oil is expected to be trucked about 350km from the Arrowsmith plant to the BP oil refinery at Kwinana, south of Perth.

The drilling of the four remaining producing wells and two water injection wells represents about 30% of the capital cost of the project. All producing wells will be highly deviated, with three currently planned as horizontal wells.

Following a tender process initiated last year, several agreements have been negotiated with several contractors.

Ensco will supply the Ensco 67 jack-up drilling rig; Baker Hughes-Centrilift will supply the electrical submersible pumps; Al Construction will undertake the design and construction of the onshore storage tanks; Clarke Energy (Aust) Pty Ltd will supply the power generation; and HL Engineering will fabricate the jacket and topside.

Day-to-day management of the Cliff Head Development Project will be out of ROC’s Perth office.

Participants in WA-286-P, Cliff Head joint venture are Roc Oil (WA) Pty Ltd (operator) 37.5%, AWE Oil (Western Australia) Pty Ltd 27.5%, Wandoo Petroleum Pty Ltd 24%, Voyager 6% and CIECO Exploration and Production 5%.