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BP heavy oil testing continues on NS A first vertical well for CHOPS testing comes on line, following a horizontal well in April; company anticipates three wells in 2013 Alan Bailey Petroleum News
BP is continuing to test the production of heavy oil from the Ugnu formation at a purpose-build facility at S-pad in the Milne Point unit on Alaska’s North Slope. The company restarted production testing at the facility in April through a single well, to assess the technical viability of heavy oil production. And according to BP’s most recent Milne Point plan of development, issued at the beginning of October, a second test well is now in operation, with a third well expected to come on line by the end of the year.
Heavy oil, with a thick syrupy consistency, cannot flow unaided through a pipeline and BP is experimenting with techniques that involve the use of an augur-like down-hole pump to suck oil up through a well to the surface, without having to apply heat to coax the oil into flowing more easily.
“BP’s heavy oil appraisal team will continue to progress pilot testing of cold recovery methods,” the plan of development says. “Three wells are planned for extended production tests in 2013.”
Four wells BP has drilled four test wells –— two horizontal and two vertical — for its heavy oil test facility. The company conducted tests in 2011 with one of the horizontal wells. The testing that began in April of this year involved the second horizontal well, leaving the two vertical wells to come on line as the year progresses.
The idea is to evaluate the effectiveness of several different techniques for drawing cold heavy oil to the surface while also gaining insights into the characteristics of different parts of the Ugnu reservoir.
In the horizontal wells the down-hole pump drops the pressure in the reservoir rock, causing gas to effervesce and hence drive oil into the well bore: The pump then pushes the oil up the well. The vertical wells, on the other hand, use a technique called cold heavy oil production with sand, or CHOPS, in which the pump draws a mixture of oil and sand through the well, with the mixture being heated in a tank at the surface to separate the two materials.
Production volumes At the end of May BP reported that the horizontal well in operation at that time was producing oil at a rate of about 350 barrels per day. And, according to data reported by the Alaska Oil and Gas Conservation Commission, production from the Ugnu ranged from 6,300 to 11,600 barrels per month between May and July, with no production in August. However, this data should probably be viewed more as a measure of testing activity rather than as a measure of ultimate heavy oil production potential.
The estimated total volume of 12 billion to 18 billion barrels of heavy oil in the Ugnu represents a huge, untapped potential energy resource. But, with testing still in relatively early stages, the technical and economic viability of North Slope heavy oil production remains something of an unknown.
Geologists think that the heavy oil in the Ugnu consists of the remnants of oil that spilled upwards from the deeper Prudhoe Bay oil field reservoir millions of years ago, when forces in the Earth’s crust caused the reservoir structure to tilt. Oil consuming bacteria that tend to be active at relatively shallow depths subsequently degraded the Ugnu oil, causing the oil to thicken and become increasingly viscous.
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