Project: Denver Unit
Company/Alliance: Occidental Oil and Gas Corp.
Location: Denver Unit CO2 Recovery Plant, Denver City, West Texas, USA
Operation Date: 2016 to 2026
Size: 1 Mt/yr
CO2 Source: Permian pipeline delivery system (both anthropogenic and natural sources)
Oil Field Storage Site: Wasson Field, West Texas
Injection Depth: 5,000 feet
Reservoir Type: The Wasson Field is located in the Permain Basin at 5,000 feet depth. The field produces oil from the San Andreas formation which is layer of permeable dolomites which were deposited in a shallow marine environment during the Permian Period.
The Wasson Field was discovered in 1936. The field had almost 4,000 million barrels of original oil in place. This made it one of the largest fields in North America. The field is split into 6 units, the largest of these units is the Denver Unit which is located in the formation's geologic high point.
CO2 flooding of the Denver Unit began in 1983 and has continued and expanded since that time. The Wasson Field's Denver Unit CO2 EOR project produced more than 120 million incremental barrels of oil between 1930 and 2008. Due to the nature of CO2 flooding, some of the injected CO2 is produced and some is sequestered in the reservoir. Between 2014-2021 the forecast is for up to 31.8 MMMT (603/5 Bscf) of CO2 to be stored.
The San Andres reservoir is capped with the upper San Andres formation which is nearly 400 feet of impermeable dolomite. Oil and gas have been trapped in the San Andres Formation for 50-100 million years. There are no known faults or fractures affecting the Denver Unit which could provide an escape pathway for fluid. However as there are sources of drinking water at 2000 feet, wells are required to be cased to ensure confinement.
There are approximately 2,200 wells in the field. 600 are injection wells. Occidental has re-permited these injection wells under UIC Class VI well, or as CO2 storage wells. The MRV plan was approved by the DOE for start in 2016. The wells have been permitted for 10 years, although storage of CO2 associated with the EOR is anticipated to continue longer than that.
Occidental Petroleum is also developing a $1.1 billion natural gas processing plant in West Texas that will capture about 265 billion cubic feet (13.5 million metric tons) of CO2 per year for use in CO2 EOR operations in the area.
Project Link: Denver Unit Subpart RR MRV plan (December 2015)