Enhanced Oil Recovery (EOR)
Enhanced Oil Recovery (EOR) is a more technologically advanced method of bringing production to surface than traditional methods of drilling. Occidental is an industry leader in EOR. In applicable cases, Occidental uses EOR processes such as carbon dioxide (CO2) flooding to significantly extend the economic life of producing fields. Instead of being left in place, remaining oil is developed, thereby making more efficient use of existing hydrocarbon resources and adding to domestic and global energy supplies.
Production of oil and natural gas requires energy to lift the fluids from the reservoir deep underground to the surface. The reservoir’s natural pressure provides much of this energy but is usually supplemented by artificial lift equipment. The reservoir can also be re-pressurized by injecting water or gas to mobilize and displace additional oil. Even after applying these techniques, a large quantity of oil and gas may remain in the reservoir.
CO2 EOR in the Permian Basin
In the Permian Basin of West Texas and Southeast New Mexico, nearly three-quarters of Occidental’s EOR business unit oil production is from fields that actively employ CO2 flood technology (CO2 EOR). Occidental injects 2.6 billion cubic feet per day of CO2 in the Permian, more than 950 billion cubic feet per year, which makes Occidental the largest CO2 injector in the Permian and one of the leaders globally.
In carbon dioxide flooding, injected CO2 releases trapped oil from porous rocks in the reservoir and causes it to flow more easily to the wellhead.
During this process, a mixture of oil, natural gas, and a portion of the injected CO2 flows into nearby wells and is produced at the surface. The CO2 is recovered from this production stream and re-injected in a closed loop process that results in additional oil recovery. Over time, virtually all of the CO2 introduced into a field becomes trapped underground, occupying the pore space left after the oil and associated gas are produced.
Applicable to a variety of suitable oil and gas reservoirs, CO2 EOR can increase ultimate oil and associated gas recovery by 10 to 25 percent in the fields where it is employed.
Occidental uses advanced flood surveillance tools to monitor its more than 1,900 patterns of CO2 injection and oil production wells throughout the Permian Basin. Occidental’s standardized methods of surveying CO2 floods in the Permian enables more efficient allocation and utilization of carbon dioxide.
Environmental Benefits
CO2 EOR benefits the environment in three ways:
- First, recovering additional oil from existing fields requires fewer resources than installing new infrastructure and equipment in new locations. Thus, EOR maximizes the efficient use of existing infrastructure and reduces land and habitat disturbance.
- Second, expansion of EOR operations as additional manmade sources of CO2 become available has the potential to substantially reduce greenhouse gas emissions — by capturing the CO2 instead of releasing it into the atmosphere. Currently, the majority of CO2 that Occidental uses is produced from natural underground CO2 reservoirs. Occidental is actively developing projects that will capture CO2 emissions for use in our EOR operations, and we are seeking other economic manmade sources of CO2.
- Third, because carbon dioxide becomes trapped in deep, underground formations, CO2 EOR can provide information and experience that will help foster full-scale commercial deployment of other carbon capture and storage technologies.
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