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How much oil can be recovered at Redoubt Shoal? Estimates range from ‘more than 50 million barrels’ to 193 million barrels, but the results of the fourth well should soon provide some more definitive answers, says Forest Oil’s Gary Carlson Kay Cashman PNA Publisher
Three estimates have been discussed in the last four months as likely amounts of oil to be recovered from the Redoubt Shoal field in Cook Inlet.
Gary Carlson, Forest Oil Corp.’s senior vice president in Alaska, consistently quotes “more than 50 million barrels.”
Executives from Forest’s Denver office told analysts in October, 113 million barrels is likely.
State geologists have gone as high as 193 million barrels.
The offshore field is thought to hold 450 million barrels of oil in place — 400 million barrels in the southern and central fault block — penetrated by the first two wells — 40 million barrels in the northern sliver and an additional 10 million barrels at the northern edge of the field.
An 11 percent recovery rate would yield Carlson’s 50 million barrels.
The Denver executives were quoting a 25 percent return, a number Carlson told PNA Oct. 1 is reasonable when water flood is used, which it will be at Redoubt.
A 43 percent recovery rate similar to the nearby Trading Bay unit would yield the state’s estimate of 193.5 million barrels.
Why the discrepancies in recovery rates? Who’s right?
Not the state, Carlson said.
“There has been water flood at the Trading Bay unit for 35 years. There are faults in our unit, at Redoubt, that you can’t water flood,” he told PNA Jan. 21.
“From a geological standpoint the Trading Bay unit is not that far away from Redoubt. … And, distance-wise, it’s maybe 5 miles. The difference is the producing zone, Hemlock, is buried a lot deeper at Redoubt than it is at the McArthur River field. Twenty-five hundred feet deeper. And that makes all the difference,” Carlson said. “We’re not going to get the kind of recovery you get at Trading Bay.”
Sixteen thousand feet and still drilling But all estimates could be wrong after Forest evaluates the results of its fourth well, which it’s drilling now. That well is expected to delineate the eastern boundary of the north fault block previously discovered by the No. 1 well.
“Right now we think there are 450 to 500 million barrels of oil in place at Redoubt. But once we get No. 4 well done we’ll have a much better idea of what we have because it’s a long reach (directional) well,” Carlson said.
On Jan. 21, Nabors Alaska Drilling Inc. was at “16,000-plus feet on the way to about 20,000 feet,” he said.
“We’re hoping to see what primary target looks like by mid-to-late February. No. 4 should tell us how big the field is going to be.” Carlson said.
First oil production at Redoubt is expected to occur before the end of the year.
Forest said in late October that its No. 3 well encountered a natural gas zone. Logs indicated approximately 40 net feet of gas pay, which was tested at 8.5 million cubic feet a day. The company said it was examining the implications of this natural gas discovery, but believes that, at a minimum, the natural gas will reduce field level fuel costs associated with oil production.
Forest has 100 percent working interest in Redoubt.
Editor’s note: For previous stories about Redoubt Shoal go to PNA’s electronic archives on at Web site http://www.petroleumnewsalaska.com/ The archives go back approximately one year, but are expected to be complete by June 1.
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