Project Profile
Value: US$323 million
Location: 11km off the coast of Western Australia, permit WA-286-P, Australia
Reserves: 7.5 million barrels (remaining from 2010)
Start-up Year: May 2006
Water Depth: 16m
Area: 6km²
Cliff Head oil field is situated 11km off the coast of Western Australia at a water depth of 16m. The field covers 6km² in the Commonwealth exploration permit WA-286-P and is the first to be developed in the offshore Perth Basin. The development cost of the field was US$323 million and first oil achieved in May 2006. Roc Oil (WA) Pty Limited is the operator via its subsidiaries with 42.5% interest and AWE held a 57.5% interest till October 2015, when Elixir Petroleum Limited bought its share.
The Cliff Head field was discovered in December 2001 by the Cliff Head-1 discovery well. Drilled by the ENSCO 56 jack-up rig, the well encountered a 5m oil column. Between 2002 and 2005, three appraisal wells were drilled, confirming the presence of hydrocarbons at the field. A production test carried out on one of the wells, stabilised rates of up to 3,000bpd were observed. Cliff Head produces from Permian sandstones of the Dongara Formation and Irwin River Coal Measures, sealed by the Triassic Kockatea Shale. The proven and probable reserves of the field were initially estimated at 14.8 million barrels, but revised to 17.8 million barrels at the end of 2010. The proven and probable reserves remaining as at 31 December 2010 were 7.5 million barrels. The oil is waxy and viscous in nature with an API of 330. It has high pour point and very low gas-to-oil ratio.
Field development
The final investment decision to develop the field was taken in March 2005. The field development plan included six production wells and two water injection wells. Between October 2005 and December 2005, the Ensco 67 jack-up rig completed the drilling of the wells. The production wells are fitted with ESPs (electric submersible pumps), which provide down-hole pressure and temperature monitoring. In January 2010, Roc Oil completed a workover to replace an ESP at the CH-10 production well. The new ESP increased field production rate to 5,000bpd. A new ESP was also installed at the CH-6 production well. Roc Oil is currently exploring potential reserves near the field. In January 2011, installation of a higher-rate ESP at production well CH-12 was initiated.
Contracts
WorleyParsons provided site investigations and geotechnical services for the platform, pipeline and the Arrowsmith plant. In 2005, Coe Drilling was awarded a contract for providing drilling services for installing the production pipeline and umbilicals. Plexal Group was awarded an engineering services contract for the field in 2006. Plexal won a second contract in 2009 to design a substructure to support a hydraulic workover unit for the platform. Bass Marine carried out mooring inspections at the field. It is also responsible for long-term cargo transfers for the platform. RISC, an independent engineering consultant, was involved in the pre-construction and engineering phase of the field. Weatherford International provided drilling services for the field. ICON Engineering was contracted to install and commission the platform and topsides at the field.
Operators:
Triangle Energy: Operator with 78.75% interest
Royal Energy Pty Ltd (private company - no website): 21.25%
Contracts:
WorleyParsons: Site investigations and geotechnical services for the platform, pipeline and the Arrowsmith plant
Coe Drilling: Providing drilling services for installing the production pipeline and umbilicals
Plexal Group: Engineering services contract and contract to design a substructure to support a hydraulic workover unit for the platform
Bass Marine: Mooring inspections at the field
RISC: Pre-construction and engineering services
Weatherford International: Drilling services
ICON Engineering: Install and commission the platform and topsides at the field
Ensco: Drilling contract