The northern portion of the Rocky Mountain region of the US may see more enhanced oil recovery projects as carbon dioxide from new sources becomes available because of concerns about the need for carbon capture and sequestration.
CO2 injection for enhancing oil recovery holds much promise as demonstrated by the many successful projects in the Permian basin of West Texas and elsewhere, but CO2 availability has been one factor limiting its use.
In the US, CO2 injection has accounted for the recovery of about 1.5 billion bbl of oil, and CO2 sales to US EOR projects reached an estimated 3 bcfd in 2008, with about 83% of it coming from CO2 source fields, according to a presentation at the Third Annual Wyoming CO2 Conference, Casper, Wyo., June 23-24.
The ExxonMobil Corp.-operated Shute Creek gas processing plant in the southwestern part of Wyoming has provided, since 1986, most of the CO2 for EOR projects in the region.
Encore projects
Recently Encore Acquisition Co. announced plans to purchase 50 MMcfd of CO2 for its Bell Creek EOR project in southeastern Montana from the ConocoPhillips-operated Lost Cabin gas plant in Fremont County, Wyo. (OGJ Online, June 29, 2009). The project involves building compression facilities adjacent to the plant and installing a 206-mile pipeline to transport compressed CO2 to Bell Creek.
Encore estimates that CO2 injection will recover an incremental 30 million bbl of oil during the project’s 20-25 year life.
The company also has plans to inject CO2 in various reservoirs on the 120-mile long, 6-mile wide Cedar Creek anticline, which lies mostly in Montana and extends into North Dakota. Cedar Creek is about 120 miles from Bell Creek.
Encore estimates CO2 injection potentially could recover about 200 million bbl of oil from Cedar Creek.
CO2 sources
Two potential new sources for CO2 in Wyoming are a proposed underground coal gasification (UCG) project in the Powder River basin and a coal gasification and liquefaction project near Medicine Bow, Wyo.
Linc Energy Ltd., Australia, plans to start a UCG pilot by mid-2011 after it finalizes the purchase of the GasTech Inc. acreage in the Powder River basin of northwest Wyoming.
The other project is the Medicine Bow Fuel & Power LLC facility, which includes a coal mine adjacent to a coal-to-liquids plant. The first phase is slated to produce about 21,000 b/d of ultralow-sulfur diesel fuel.
A presentation at the Casper conference estimated that these two projects could supply 335 MMcfd of CO2 for EOR in 2013.
Another CO2 source that will become available in 2010 is from the completion of a $72 million expansion at ExxonMobil’s Shute Creek gas processing plant. The expansion includes installation of 23,000 hp of CO2 compression for increasing CO2 sales by 110 MMcfd from the current 230 MMcfd.
The Shute Creek plant has a 700 MMcfd of gas processing capacity and receives gas from LaBarge field in Sublette, County, Wyo. The composition of the gas from La Barge is 66% CO2, 21% methane, 7% nitrogen, 5% hydrogen sulfide, and 0.6% helium. Presentations at the Casper conference noted that the Shute Creek plant is the largest gas sweetening plant in the world, produces 25-30% of the world’s supply of helium, about 4 MMcfd, and injects the most acid gas consisting of 35 MMcfd of hydrogen sulfide and 25 MMcfd of CO2.
La Barge is also the site of a $100 million pilot for demonstrating ExxonMobil’s controlled freeze zone single-step process for CO2 separation. The company plans to start up the pilot in 2010 and expects it to be a lower cost process that may make carbon capture and sequestration a more practical option for CO2 separated from natural gas.
Currently ExxonMobil sells CO2 to five EOR projects in Wyoming and one in Colorado. The Wyoming projects are the Anadarko Petroleum Corp.-operated Patrick Draw (Monell Unit) and Salt Creek fields, Devon Energy Corp.-operated Beaver Creek field, and Merit Energy Co.-operated Lost Soldier and Wertz fields.
In Colorado, Chevron Corp. operates an EOR project in Rangely field that receives CO2 from Shute Creek.
A presentation at the Casper conference estimated that potential EOR projects in Wyoming could need up to 2.68 tcf of CO2 to recover about 418 million bbl of oil.