Nexen Inc. has begun production from the 12th pad at its Long Lake oil sands project and steaming of the 13th pad, saying it is adjusting work to quality of the complex resource in the southern Athabasca region of Alberta (OGJ Online, Apr. 16, 2012).
The company is using steam-assisted gravity drainage to produce bitumen for an integrated upgrader that gasifies asphaltenes in the bitumen into synthesis gas for use as a fuel and source of hydrogen for a hydrocracker.
It expects to achieve production of 30,000-44,000 b/d from the first 11 pads this year or next and of 11,000-17,000 from the 12th and 13th pads in 2014-15.
The project is designed eventually to produce 72,000 b/d of bitumen, from which the upgrader will yield 60,000 b/d of synthetic crude oil. The upgrader began operation in 2009 and has achieved as much as 60% overall capacity utilization during tests.
Actual project production, recently reported at 34,500 b/d, is slightly more than half original expectations.
In a new report, Nexen says it is adapting to the presence of lean zones of mobile water that draw large amounts of steam early and reduce production and increase steam-oil ratios (SORs). Once mobile water heats, performance improves. Nexen says high fluid rates reduce time to improvement.
In response to multiple channeling events in the Long Lake resource, the company has increased the frequency of core-hole drilling. Well performance from the first 10 pads showed discontinuous shales act as barriers to steam-chamber growth when enough of them exist. Nexen drilled more than 200 core holes last winter and plans similar programs during the next 3 years.
It says one of several lessons from Long Lake is the “need for resource calibration−understanding [the] relationship between clean sand, shales, lean zones, and their impact on rate and SOR.”