BP is getting very good results from the first of four test production wells drilled into the Ugnu heavy oil deposit on the Alaska North Slope, company officials said in an interview Tuesday.
The well produced up to 650 b/d of oil mixed with sand and with the sand removed the net production was about 550 b/d, said Eric West, BP's manager on the project. Production began on April 22.
"It was higher than we expected. It is a good well," West said.
BP spokesman Steve Rinehart added, "It is good result so far with this one well and at this location" in the reservoir.
The Ugnu has huge in-place heavy oil resources with estimates as high as 23 billion barrels of oil in place in the reservoir, but BP and other producers have worked for several years on ways of producing the oil. The pilot program under way now will test two different production technologies with four wells that are being drilled to different spots in the reservoir to assess how differing reservoir conditions will affect production, West said.
A key difference between this series of tests and heavy oil production techniques in places like California, where steam is injected, is that BP wants a cold production process that avoids any warming of the permafrost layer that extends to about 2,000 feet under most of the North Slope.
The wells were drilled at S Pad in the Milne Point field. The first well brought online, designated S-41, is a conventional horizontal production well that works with a progressive cavity pump that creates suction in the well to pull the oil and sand mixture out of the formation and up the well, West said. The sand, along with solution gas, is separated at the surface.
The second well to be brought online is a "CHOPS" well (cold heavy oil with sand), a well type developed in Canada to produce heavy oil and brought to the North Slope by BP. West said the CHOPS well is drilled vertically. When production begins the progressive cavity pump will draw oil out of the formation and create small fissures that extend into the formation, allowing more fluids to flow.
BP will test two CHOPS wells and one other horizontal production well in the test program, West said.
The S-41 well was taken temporarily out of production to allow BP to replace casing where wear had occurred from a rotating rod that runs the progressive cavity pump, and to make changes in the processing plant at the surface to solve a gas-handling problem, but such startup problems were expected with a new production system, West said.
BP and other North Slope producers are looking to production from large unconventional oil resources like the Ugnu heavy oil to supplement declining production from conventional oil fields on the slope. The Ugnu oil produced at S-41 has a gravity of 12 API, West said, but the oil quality from different parts of the formation is expected to vary.
The test production wells were drilled to a deeper part of the Ugnu at about a 4,000-foot depth, but parts of the reservoir at shallower depths will be more difficult to produce and may require a heat source to warm the oil, West said.
BP and ConocoPhillips are also producing viscous oil, a somewhat better quality oil that with gravity of about 18 API, from the Shrader Bluff deposit in the Milne Point field and the West Sak formation in the Kuparuk River field, which is nearby.
