Solving The Problem of Interwell Pressure Communication

As shale oil development has progressed using horizontal wellbores completed at increasingly closer lateral spacing, multistage fracture stimulation treatments often propagate fractures that extend to offset wells and cause these wells to be in hydraulic or pressure communication. And, in some areas, natural fractures may extend between these wellbores, that are in hydraulic or pressure communication.

 

As a result, implementation of cyclic natural gas or CO2 EOR processes in these wells may result in poor incremental oil recovery, as pressure buildup during injection cannot be achieved sufficient to drive the injectant gas into the matrix oil, and injected gas may move away from the well to offset wells and/or be unrecoverable.

 

This problem has been observed in several of the Eagle Ford shale, Permian Wolfcamp shale, Williston Basin Bakken and SCOOP Springer shale natural gas and CO2 EOR projects. Efforts to mitigate this problem have included methods such as pressuring up wells offset the injector with water, shutting offset wells in, or pressuring up offset wells with natural gas. These efforts may work to some extent, but EOR oil recoveries are usually much lower than needed for good project economics. 

The SuperEORTM process can operate very effectively to recover far more oil than natural gas or CO2 cyclic EOR, at much lower bottomhole pressures. 

The graph below shows the recovery of oil via SuperEORTM in an Eagle Ford shale well at varying maximum buttonhole pressures. As shown, cumulative oil recovery at just 1500 psig maximum BHP is just 13% lower than cumulative oil recovery when the maximum injection BHP is 4500 psig. 

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