Pressure depletion and drained rock volume near hydraulically fractured parent and child wells
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© 2018 Field development of unconventional reservoirs tends to downsize well spacing when commercial success of a shale play is proven. The earlier, so-called parent wells are joined by infill wells, commonly called child wells. Tighter well spacing improves the recovery factor but the risk of well interference increases. The flow interference and pressure communication of adjoining wells via the matrix and their hydraulic fractures was investigated using the depth of investigation and associated pressure depletion plots. A sensitivity analysis shows how the depth of investigation in an unconventional reservoir is impacted by matrix permeability, other fluid properties, and time lapse between drilling of parent and child wells. In all cases, the extent of the drained region of a reservoir with hydraulic fractures is controlled by the fluid particle paths guided by the depth of investigation and time-of-flight contours. Time-of-flight contours visualize the reservoir drainage by parent and child wells using complex analysis methods (CAM) in a case study of the Eagle Ford shale. Even after 30 years of production, the actual drained rock volume (DRV) remains small and lags the depth of investigation. A commercial numerical reservoir simulator provides history matched inputs for the CAM tool which then can model the flow near the discrete fractures in the reservoir at high resolution. The developed procedure provides a computationally efficient method to quantify and visualize the DRV for parent and child wells in hydraulically fractured reservoirs. Fluid particle tracking provides a practical method to determine fracture and well-interference in combination with depth of investigation and pressure depletion studies.
author list (cited authors)
Khanal, A., & Weijermars, R.