Causeway oil field is located in blocks 211/22a and 211/23d of production licenses P.201 and P.1383 of the northern North Sea, UK. It lies in a water depth of 492ft. The field is situated approximately 93 miles east of the Shetland Islands and 13.6 miles west of the UK / Norway international boundary.
The field is being developed along with the Fionn oil field. The two fields are estimated to hold maximum recoverable reserves of 10.42 million barrels.
Causeway was anticipated to come on-stream in September 2012, but was delayed due to bad weather conditions in the North Sea. The field is now scheduled to commence initial production in November 2012.
Valiant Petroleum, through its subsidiaries Valiant Causeway and Valiant Gamma, controls a majority 64.5% working interest in the Causeway project and is the operator of the field. The remaining 35.5% share is owned by Antrim Resources, a wholly owned subsidiary of Antrim Energy.
As per an oil sales agreement signed in August 2012, BP will purchase Antrim’s share of oil produced from the project.
Discovery of Causeway oil field
Causeway was discovered in April 1984 by the 211/21a-3 discovery well. It flowed at the rate of 5,512 barrels of oil each day (bopd) from a Jurassic reservoir. The sandstones of the reservoir belong to Jurassic Brent Group. Another undeveloped discovery well, designated as 211/23b-11, was drilled in 1992. It flowed at the rate of 8,100bopd.
A sidetrack well, 211/23d-17z, drilled in July 2006, encountered 1,185ft of net oil. Initial testing of the well was completed in August of that year.
Three additional wells were drilled in 2007 as part of a drilling programme. The 211/22a-6 well was drilled to a total depth of 12,260ft and flowed at the rate of 6,300bopd. The second well, 211/22a-7A, was completed in August 2007 after drilling to a depth of 11,960ft. Drilling of the third well, 211/22a-8, was completed in September 2007.
Another appraisal well, 211/22a-9, was drilled to a total depth of 14,045ft in October 2007.
Development of the North Sea field
The final field development plan (FDP) for the Causeway project was submitted to the UK Department of Energy and Climate Control (DECC) in August 2011. The development scheme was sanctioned in December 2011.
The Causeway field will be initially exploited through two wells. One of these will be a production well and another will be utilised to inject water. Both wells will be tied-back to the North Cormorant platform operated by Taqa Bratani. The wells are planned to be drilled through a semi-submersible drilling rig.
The production well will be tied-back to a subsea manifold through a 1.8-mile long infield flowline. From the manifold, the reservoir fluid will be transported via a 9.7-mile subsea pipeline to the host platform for processing. The processed oil will then be sent to the Sullom Voe terminal for distribution.
A 9.3-mile long water injection pipeline and associated electro-hydraulic control umbilical with conduits for chemical injection will also be installed. As of October 2012, all subsea construction work was completed. Commissioning of the topsides at the host platform is being carried out.
A submarine pipeline plough was used to entrench the production flow-lines, water injection pipeline and the umbilicals. The leftover trench was mechanically backfilled.
Contractors involved with the UK oil discovery
AGR Peak Well Management was commissioned in March 2006 to provide well project management services for the 2006 Causeway drilling programme. The company was again contracted in November 2006 to complete the 2007 drilling programme.
GE Oil & Gas was contracted in September 2011 to supply subsea production trees, a subsea injection tree and rental tooling for the project.
Technip was awarded a lump sum contract to provide engineering, procurement, installation and commissioning of rigid and flexible pipelines, subsea equipment and umblicals.
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