Two Superior Shale Oil Enhanced Recovery Methods for the Utica Shale

Abstract

Abstract The Utica Shale is a very large, important oil and gas resource in the eastern United States. While gas production dominates, oil production from horizontal shale oil wells in the Utica has grown from 15 BOPD in June 2011 to a peak of 50,000 BOPD in September, 2019 with 2,485 horizontal shale oil wells in production. The Utica shale dips to the east, shallow in east-central Ohio to deep in western Pennsylvania. Likewise, hydrocarbons in the Utica trend from light oil with low GOR in eastern Ohio to dry gas in western Pennsylvania. Liquid hydrocarbons are produced from the shale via solution gas drive. The shallow, black oil area of the play has to date been noncommercial. A recent enhanced oil recovery test in the shallow black oil area of the Utica has provided encouraging results. Our objective is to introduce two novel EOR processes that can greatly increase the production and recovery of oil and gas from the Utica shale, while reducing the cost per barrel of recovered oil, and reducing GHG emissions and water consumption/production/disposal. Two superior shale oil EOR methods are proposed that utilize 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. One of the methods also incorporates the application of rock mechanics to further enhance oil and gas recovery. The processes are designed and integrated during operation using compositional reservoir simulation in order to optimize oil recovery. Compositional simulation model of a Utica shale horizontal well producing rich gas condensate was conducted to obtain a history match on oil, gas, and water production. The matched model was then utilized to evaluate two novel shale oil EOR methods under a variety of operating conditions. The modeling indicates that for this particular well, incremental oil production of 500% over primary EUR may be achieved in the first five years of EOR operation via the SuperEOR method. A further enhanced EOR method, UltraEOR, is shown to potentially increase oil recovery by 850% in the first five years of EOR operation, and as much as 1100% after 12 years. These methods, which are patent-pending, have numerous advantages over cyclic gas injection, such as much greater oil recovery, much better economics/lower cost per barrel, reduced gas containment issues, 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. These superior shale oil EOR methods have been modeled in seven major US shale oil plays, indicating large incremental oil recovery potential. Core tests have confirmed the SuperEOR modeling results and demonstrated high oil recovery, and field tests have been successfully completed that confirm reservoir simulation modelling projections. If implemented early in the life of a shale oil well, application of these processes can slow the production decline rate, recover far more oil earlier and at lower cost, greatly improve profitability and extend the life of the well by several years, while precluding the need for artificial lift.