The Explorers 2008: XTO teases out Cook Inlet oil

Company keeps the production going in its Middle Ground Shoal field

Alan Bailey

Petroleum News

Since XTO Energy (then operating as Cross Timbers Oil Co.) purchased the Middle Ground Shoal field offshore in Alaska’s Cook Inlet from Shell in 1998, the company has done sterling work in maintaining oil production at the field, and in increasing the field reserves.

The company has kept the field producing at a rate in the range of 3,000 to 4,500 barrels per day, while increasing reserves from 12 million barrels to 24 million barrels. Total production for 2007 was 1.1 million barrels, while 2008 production to the end of August was 718,739 barrels.

XTO’s operation at Middle Ground Shoal dovetails into the company’s overall strategy of squeezing the maximum of oil from known fields, often purchased from major oil companies. XTO personnel have learned the craft of developing hidden reserves in these fields.

Middle Ground Shoal production comes from multiple horizons within the Tertiary Tyonek formation, in a structure with a shallow dipping east flank, a steep west flank and a faulted crest. XTO has developed new reserves by directional drilling in the west flank, where the strata are essentially tipped on end. The company has also maintained production through coiled drilling work on production wells, injection well workovers and artificial lift optimization.

Reservoir pressure is maintained by injecting filtered water from the Cook Inlet.