|
BP’s LoSal test at Endicott succeeds The new enhanced oil recovery technique may deliver more than 700 million barrels of oil from the company’s worldwide assets Alan Bailey Petroleum News
BP’s trademarked LoSal enhanced oil recovery test in the Endicott field on Alaska’s North Slope has successfully demonstrated the possibility of recovering as much as 20 percent of the remaining oil in place in a field reservoir, BP spokesman Steve Rinehart told Petroleum News April 6.
The test, involving the injection into the reservoir of low salinity water rather than the saline water typically used to flush oil from an oil field, fully met the company’s expectations.
“We came out of this feeling very good,” Rinehart said. “We’re looking at this as a pretty significant breakthrough.”
Verify the technique BP designed the test at Endicott to verify the viability of the LoSal technique and the company is now evaluating where best within its worldwide portfolio of oil fields to put the technology into full operation.
“We’re looking for and assessing targets, but we’re not at a point yet where we can say ‘OK, we’re going to do LoSal next in this location or that one,’” Rinehart said. “… We showed that it worked and now we want to put it to work.”
BP has in the past said that the cost of implementing a full-scale LoSal operation in a specific field will depend on factors such as the availability of a suitable low-salinity water source at the field and the extent to which oil wells need to be reconfigured to support the operation. However, in a region such as the North Slope, even a small increase in field oil recovery can represent a large amount of new oil production.
Worldwide, the use of the technique could result in the recovery of more than 700 million barrels of oil from BP’s oil fields, Rinehart said.
Trademarked in 2005 BP trademarked its LoSal technology in 2005 after laboratory testing had demonstrated that low-salinity water can be more efficient than saline water in sweeping oil from the pores of oilfield reservoir rocks. The technique works because low-salinity water is especially effective in severing the electric bonds that hold molecules of oil to the clay that typically coats sand grains in a reservoir rock — the oil attaches to the clay rather like Velcro, with the water disconnecting the Velcro hooks.
However, because a lab test does not prove that a technique such as LoSal will work properly in a full-scale oilfield situation, BP decided to conduct a field test. And Endicott, as a mature oil field with a substantial volume of oil remaining in place, turned out to be an optimum test location.
The company sanctioned the Endicott test in 2006 and began by pumping water in and out of single wells, to test the effectiveness of low-salinity water in moving oil that lay close to a well.
In December 2007 BP began a major, conventional waterflood operation in the field, to establish baseline oil recovery data, to enable a later determination of how much additional oil the LoSal technique would remove, Rinehart said.
Started June 2008 Then in June 2008 the company started pumping low salinity water at a rate of about 5,000 barrels per day into a single injection well, to cause an expanding pool of this water to move through the reservoir towards a production well, gathering oil along the way. Careful positioning of the test within the Endicott reservoir ensured a geologic setting that would channel the water along a path towards that single production well.
“This was a well-to-well test,” Rinehart said. “The bottom-hole locations were approximately 1,000 feet apart.”
Three trucks continuously delivered fresh water from a gravel pit for the water injection operation, he said.
In May 2009 changes in the chemistry of water passing up the production well indicated that the leading edge of the package of low salinity water had crossed the oil reservoir between the injection and the production wells. It was then possible to start measuring the oil recovery associated with the low-salinity water and thus estimate how much oil recovery to attribute to the LoSal technique.
Completion of these measurements and subsequent analysis of the results has enabled BP to derive the figure of a potential 20 percent recovery of remaining oil in place from LoSal at Endicott.
“We’ve got a tool out of this that promises to be very useful,” Rinehart said.
| 