Evaluation of a Superior Shale EOR Application in the Eagle Ford Shale

Oil production from horizontal shale oil wells in the Eagle Ford began in 2008 and reached a peak of 1.65 Million BOPD in March 2015. By November, 2020, 25,210 shale oil wells were producing 754,000 BOPD. Estimated oil recovery from the Eagle Ford shale is 4 to 7 percent of OOIP. In this paper, we introduce a novel EOR process, designated herein as "superEOR" that can increase the production and recovery of oil from the Eagle Ford shale much more than natural gas or CO₂, while reducing the cost per barrel of recovered oil, and the environmental impacts of oil production.

A superior shale oil EOR method is proposed that utilizes a triplex pump to inject a solvent liquid into the shale oil reservoir, and an efficient method to recover the injectant at the surface, for storage and reinjection. The process is designed and integrated during operation using compositional reservoir simulation in order to optimize oil recovery. Compositional simulation modeling of Eagle Ford shale wells that have been used in a natural gas cyclic injection pilot project was conducted to obtain a history match on oil, gas, and water production. The matched model was then utilized to evaluate the shale oil EOR method under a variety of operating conditions. The modeling indicates incremental oil production of 300% over primary EUR may be achieved in the first five years of EOR operation, and more than 500% over primary EUR after 10 years.

The process can be implemented at pressures below initial reservoir pressure to mitigate interwell communication, which rendered the previous cyclic natural gas injection method ineffective. The method, which is patented, has numerous advantages over cyclic gas injection, such as much greater oil recovery, much better economics/lower cost per barrel, lower risk of interwell communication, use of far less horsepower and fuel, shorter injection time, longer production time, smaller injection volumes, scalability, faster implementation, precludes the need for artificial lift, elimination of the need to buy and sell injectant during each cycle, ability to optimize each cycle by integration with compositional reservoir simulation modeling, and lower emissions.

If implemented early in the life of a shale oil well, its application can slow the production decline rate, recover far more oil earlier and at lower cost, and extend the life of the well by several years, while precluding the need for artificial lift.