Journal of Petroleum & Environmental Biotechnology

Recent developments in enhanced oil recovery

3^rd World Congress on Petroleum Engineering and Natural Gas Recovery

July 20-21, 2018 Sydney, Australia

Dandina Nagaraja Rao

Louisiana State University, USA

Posters & Accepted Abstracts: J Pet Environ Biotechnol

Abstract:

The current commercial practice of gas-based enhanced oil recovery processes involves either continuous gas injection (CGI) or Water-Alternating-Gas (WAG) injection. Over 60 commercial projects in West Texas and other parts of the world have amply demonstrated that these CGI and WAG processes have been technically successful and commercially profitable. However, the oil recoveries from the CGI and WAG processes fall in the range of 5-15% of the remaining oil. The Gas-Assisted Gravity Drainage (GAGD) process, invented and patented at LSU, has yielded oil recoveries in the range of 65-95% in laboratory experiments conducted at realistic reservoir conditions. Field scale simulations also support the laboratory findings and efforts are underway to test the process in an actual Louisiana oilfield. The GAGD process involves utilizing several vertical wells for injection of CO2 in addition to drilling long horizontal wells for production. Injected CO2 accumulates at the top of the pay zone due to gravity segregation and displaces oil, which drains to the horizontal producer. This maximizes the volumetric sweep efficiency. The gravity segregation of CO2 also helps in delaying or even eliminating CO2 breakthrough to the producer as well as preventing the gas phase from competing for flow with oil. This predictability of the frontal position of injected CO2 is unlike that in a WAG process, wherein there is little control over the breakthrough of the injected CO2 gas at the producer, thereby complicating any CO2 sequestration effort. Thus GAGD enables sequestering injected CO2 in addition to yielding much higher recoveries of trapped oil from depleted reservoirs. This presents a unique opportunity for CO2 emitters and oil companies to synergize their resources to pocket higher profits in the form of improved oil recoveries as well as sequestering the CO2 to ensure a cleaner and safer environment.