Marathon applies to expand pad surface at Kenai gas field

Kristen Nelson

Marathon Oil Co. has applied to fill a former reserve pit at the Kenai gas field with gravel to provide more pad surface for up to two gas wells. The company told the U.S. Army Corps of Engineers that the additional gravel pad surface would also be used for remedial well work.

The former reserve pit at Pad 14-6 was constructed by Unocal in 1981. The Corps said the Alaska Department of Environmental Conservation determined in 1985 that the pit had not been permitted in accordance with solid waste management regulations. Removal of the drilling waste was begun in 1993 and completed in 1994. The former reserve pit has been inactive since.

Marathon is proposing to lay 7,484 cubic yards of gravel in 1.45 acres of wetlands. The Corps said the reserve pit and current production pad “were constructed within a large wetland complex” south of Kenai, on land owned by the Salamatof Native Association Inc.

The reserve pit and existing production pad 14-6 authorized by the Corps in 1981 included 74,000 cubic yards of gravel material on 5.5 acres of wetlands for a 260-foot by 400-foot drill pad, a 240-foot by 346-foot pad for a dehydration building, compressor building, office and shop building; and a 100-foot by 400-foot reserve pit, “to expand the existing commercial drilling and gas production site.”

While this application is for space to allow for drilling of two new wells, Marathon told the Corps that it will need to drill up to four new wells to recover remaining gas in the field.

The Kenai is Cook Inlet’s largest gas field. It was discovered by Unocal in 1959 and production began in 1961. The field is now owned and operated by Marathon, which holds 100 percent working interest.

In its 2003 annual report the Alaska Division of Oil and Gas said the Kenai gas field produced 2.22 trillion cubic feet of gas through 2002 and is expected to produce an additional 141.4 billion cubic feet from 2003 through 2014, when production is estimated to end. The division said it assumes production level at the same rate as 2001 through 2006, after which production will decline, with an estimated decline rate of 11.6 percent after 2007. Production is from the Sterling, Beluga and Tyonek formations. The field produced almost 20 billion cubic feet in 2001, and more than 22 bcf in 2002.