Homer Alaska - Business

Story last updated at 11:47 AM on Wednesday, July 6, 2011

USGS: Lots of gas, oil in Cook Inlet

By Tim Bradner
Morris News Service - Alaska

A U.S. Geological Survey report released June 28 says the Cook Inlet region contains an estimated mean natural gas resource of 19 trillion cubic feet of gas, about 600 million barrels of oil and 46 million barrels of natural gas liquids.

The estimate is of undiscovered, technically recoverable oil and gas resources and includes both unconventional and conventional resources, the USGS said.

The gas estimates are significantly more than the last USGS assessment of southern Alaska in 1995, in which a mean of 2.14 trillion cubic feet of gas was estimated. The increase in the undiscovered resource is attributed to new geologic information and data, the agency said. The estimate for undiscovered oil in the 1995 assessment was 646 million barrels.

"For the first time, USGS has evaluated unconventional as well as conventional petroleum resources in the Cook Inlet region of Alaska," said Brenda Pierce, USGS Energy Resources Program coordinator.

Since oil and gas production began in the Cook Inlet region in 1958, more than 1.3 billion barrels of oil and 7.8 trillion cubic feet of gas have been produced, yet the new USGS assessment shows that significant undiscovered gas remains.

This USGS assessment includes estimates of conventional and unconventional, or continuous, accumulations, including coalbed gas and tight gas formations, the USGS said.

Coalbed gas is a form of natural gas extracted from coal deposits, whereas tight gas is natural gas occurring in impermeable, compact rock formations.

Both require different development techniques than conventional gas accumulations.

The USGS assessment of undiscovered gas resources ranges from 4,976 to 39,737 trillion cubic feet (95 percent and 5 percent probability, respectively). Of this total, about 72 percent is estimated to be found in conventional accumulations, 25 percent in coalbed gas accumulations, and 3 percent in tight gas accumulations.

The assessment of undiscovered oil resources ranges from 108 to 1,359 million barrels of oil (95 to 5 percent probability, respectively). These resources are all conventional resources; there are no unconventional oil resources assessed in the Cook Inlet region.

The new estimates are for technically recoverable oil and gas resources, or oil and gas producible using currently available technology and industry practices, regardless of economic or accessibility considerations, the USGS said.

The estimates include resources beneath both onshore and offshore areas of the Cook Inlet and are exclusive of the federal outer continental shelf, the agency said. However, they include areas where accessibility may be limited by federal agencies and laws.