ConocoPhillips Alaska shops for partner at Cosmopolitan

Pat Healy

Petroleum News Contributing writer (Houston)

At the North American Prospects Exposition held Feb. 5-6 in Houston, Texas, ConocoPhillips Alaska was shopping for a partner in its 70 percent working interest at the offshore Cosmopolitan prospect in Alaska’s lower Cook Inlet basin. ConocoPhillips wants to trade working interest ownership in leases and wells for future three-dimensional seismic and a delineation well.

Completed June 13, 2003, the ConocoPhillips Alaska-operated Hansen 1A, a sidetrack well drilled from onshore to a bottom hole under Cook Inlet, had a total depth of 20,789 feet, true vertical depth of 7,102 feet. The Hansen 1 was drilled in 2001-02. The discovery well at the prospect, The Starichkof State No. 1, was drilled by Pennzoil Co. in 1967. It was drilled southeast of the Hansen target from a jack-up rig and recovered oil at about 6,900 feet. While it was enough to hold the lease, Pennzoil’s discovery was never developed and the original unit lapsed.

Last April, Rick Mott, ConocoPhillips Alaska vice president of exploration and land, said the Hansen sidetrack was drilled with extended reach technology using “the largest and most powerful rig in Alaska.” The Hansen No. 1 “went down about a mile and a half and then out underneath the inlet about three miles,” Mott said, and was a “world-class accomplishment.” The sidetrack well, the Hansen No. 1A went even farther, he said.

Present unit formed in 2001

Seven state leases and two federal leases, more than 24,000 acres, make up the Cosmopolitan unit, formed in 2001. Spacing has not been set for this area, ConocoPhillips said, but is expected to be 80 to 160 acres per well. State statute-defined regulations allow for a reduced royalty rate of 5 percent on production from these state leases, applicable for 10 years to the first 25 million barrels of oil and the first 35 billion cubic feet of natural gas. Operator ConocoPhillips’ partners are Forest Oil with a 25 percent working interest and Devon Energy with the remaining 5 percent.

In its NAPE handout ConocoPhillips described the original oil in place as “significant in the combined section of the Lower Tyonek and Hemlock Sandstones. These units have been tested and are shown to flow 25 degree API gravity oil at rates greater than 500 BOPD.” The company also said that there is upside potential “for increased well production rates with better reservoir understanding,” as well as shallow gas and oil potential in thin sandstones in the Upper Tyonek formation.

This oil play is in fluvial sandstones in the Oligocene Hemlock and Miocene Tyonek formations, Lower Cook Inlet basin, the company said. An axial fluvial braid plain is the depositional environment for these sections. Net pay of more than 100 feet in the Hemlock sandstone, the primary target and more than 130 feet in the secondary target, the Miocene Tyonek are within the general reservoir parameters. The play, currently under appraisal, is described as a four-way dip closure.