East Rochelle Oil and Gas Field, Block 15/27, North Sea, United Kingdom

East Rochelle oil and gas field is located in Block 15/27 of the Greater Rochelle area (production licence P226) in the UK section of the North Sea. It lies about 72 miles away from the UK coastline in the central North Sea. The field development is situated approximately 115 miles north-east of Aberdeen, Scotland, in a water depth of about 460ft.

As of April 2012, the Rochelle field development was in the execution phase and it is expected to achieve production in the fourth quarter of 2012. The development has an expected field life of six years, with production anticipated to continue until 2017.

Working partnership between Endeavour Energy, Nexen and Premier Oil

The Greater Rochelle area is a combination of two undeveloped oil and gas fields, namely West Rochelle (blocks 15/26b and 15/26c) and East Rochelle (block 15/27).

The area is jointly owned by Endeavour Energy, a subsidiary of Texas-based Endeavour International Corporation, Nexen Petroleum UK, a subsidiary of oil and gas company Nexen, and Premier Oil, an independent upstream oil and gas company.

Endeavour has a 44% working interest, while Nexen and Premier Oil have 41% and 15% working interests respectively. Endeavour holds a working interest of 55.6% in the East Rochelle field and is also the operator of the field. The remaining 44.4% interest is owned by Nexen.

Hydrocarbon volumes and recoverable reserves at the East Rochelle field

Gas in place for the East Rochelle field for low, base and high cases is estimated to be 119 billion cubic feet (bcf), 157bcf and 195bcf respectively.

The planned recovery of gas from the field is estimated to be 68bcf for low case, 118bcf for base case and 137bcf for high case.

Condensate recovery rates are estimated to be about 2.3 million barrels (mmbbl) for low case, 4.4mmbbl for base case and 4.9mmbbl for high case.

Discovery of the Greater Rochelle area-based oil and gas field in 2000

East Rochelle field was originally discovered and drilled by the Hess Corporation (formerly Amerada Hess) in 2000 as the Rochelle field (discovery well 15/27-9). The original Rochelle field was renamed as East Rochelle after the discovery of

West Rochelle accumulation in 2010 via 15/26b-10 discovery well.

Endeavour acquired the field's licence in 2006 and drilled the appraisal well 15/27-11 in late 2008 and tested it in early 2009. The appraisal well was drilled to a total depth of 3,160m by the Sedco 704 semisub.

Endeavour submitted an environmental impact statement (EIS) for East Rochelle to the UK Department of Energy and Climate Change (DECC) in March 2010. The statement was approved in late 2010.

The field development plan (FDP) for Rochelle was approved by the DECC in February 2011.

Infrastructure development at East Rochelle and Scott platform tie-back

East Rochelle oil and gas field is being developed as a subsea tie-back to the Scott platform located in Block 15/22. The platform is operated by Nexen Petroleum and has been in operation since 1993.

Field development includes construction of up to two production wells, installation of a new production pipeline up to the Nexen's platform and tie-back of the wells to the platform. A separate 19-mile control umbilical will also be installed from the platform to the production wells to provide hydraulic / electrical control, chemicals and pipeline treatments to the wellhead locations.

East Rochelle hydrocarbons will be carried to the Scott platform via a 19-mile, 10in diameter production pipeline. From there, oil will be transported to the Grangemouth Refinery by the Forties Pipeline System and gas will be transmitted to the St. Fergus Gas Terminal via the Scottish Area Gas Evacuation (SAGE) system.

As of April 2012, full pipeline fabrication has commenced after the completion of the assembly of pipeline section. Drilling on the first production well and subsea installation are expected to commence during the second quarter of 2012. Work on the pipe will commence in the third quarter.

Contracts and contractors involved with the UK North Sea oil and gas field

In June 2011, Technip was awarded an engineering, procurement, construction and installation (EPCI) contract worth $88m for the East Rochelle development. The scope of contract includes complete project management and detailed design, assembly, installation and pre-commissioning of 19 miles of pipe-in-pipe, flexible riser, subsea isolation valves, manifolds and free issue umbilicals to control subsea structures. Other works include tie-in spools, trenching, backfill and subsea rock dumping.

The first of the two development wells will be drilled by Diamond Offshore's Ocean Nomad rig.

Subsea umbilicals and associated equipment will be supplied by Aker Solutions. The contract, signed in July 2011, is worth $15m and includes supply of one one-mile long infield control umbilical and one 2,133ft riser umbilical.