TEXACO SCHEDULES NORTH SEA SUBSEA SYSTEM

Texaco North Sea (U.K.) Co. has received British government approval to develop Strathspey field in North Sea Block 3/4a using a subsea Development system costing 398 million ($700 million). Strathspey will be one of the largest, most complex subsea developments in the North Sea. Production, to begin in 1993, will peak at 39,000 b/d of crude oil, 120 MMcfd of gas, and 4,000 b/d of natural gas liquids.

Nov. 18, 1991

3 min read

Texaco North Sea (U.K.) Co. has received British government approval to develop Strathspey field in North Sea Block 3/4a using a subsea Development system costing 398 million ($700 million).

Strathspey will be one of the largest, most complex subsea developments in the North Sea.

Production, to begin in 1993, will peak at 39,000 b/d of crude oil, 120 MMcfd of gas, and 4,000 b/d of natural gas liquids.

The field holds 89 million bbl of liquids and 334 bcf of gas reserves in two reservoirs-Triassic to lower Jurassic Statfjord and middle Jurassic Brent. Most of the oil is in Brent sandstone, most of the gas in the Statfjord.

The Brent reservoir will be developed with eight production wells and three water injectors. The Statfjord formation will require six production wells, including two horizontal holes that will penetrate the 85 ft oil rim with 2,500 ft horizontal sections.

Development drilling started last month and will continue until 1995 with breaks for installation of subsea facilities and programmed well work.

Texaco was one of the first U.K. North Sea operators to use subsea systems with development of Tartan field satellites Highlander and Petronella.

FIELD FACILITIES

The Strathspey system will consist of a central manifold into which 15 new wells and two existing appraisal wells will be tied. Flows from the wells will move through a series of flow lines to Chevron U.K.'s Ninian Central platform.

A separate production and well test flow line will be provided for each of the reservoirs because different pressures make it impossible to mix the fluids subsea. Brent has an initial shut-in wellhead pressure of 3,500 psi, while Statfjord's is 5,500 psi.

About 88,000 b/d of injection water will move from Ninian's southern platform to the central manifold through a 13.6 mile flow line.

The 15 new wells will be clustered around Strathspey's central manifold. The two existing appraisal wells, which will be completed as producers, are 1.3 miles away.

Chevron will use an existing process train on Ninian central to handle Brent oil production, but a new module will be required to process Statfjord gas. Ninian is linked by pipeline to the Sullom Voe, Shetland Islands, oil terminal. A 16 mile, 16 in. gas pipeline will be laid to the Brent A platform and the FLAGs gas pipeline system.

Jim Hale, Texaco's Strathspey project manager, said Texaco does not have the infrastructure in the area to support a subsea development that requires a host platform for processing oil and gas. Years ago, he said, it would have seemed highly improbable that such an agreement to use the facilities of another company could be reached.

Texaco holds a 67% interest in Strathspey. Its partners are Shell U.K. Ltd. and Esso Exploration & Production U.K. Ltd. 13.25% each and Oryx U.K. Energy Co. 6.5%.