Time-lapse seismic monitoring of hydraulic fracture stimulations within the Niobrara-Codell Reservoir Wattenberg Field, Colorado

Abstract

Time-lapse seismic interpretation is demonstrated as a viable method for observing physical modification of a tight reservoir resulting from the hydraulic fracturing process. Compressional seismic data sets were acquired before and after completions of 11 horizontal wells within a section (one-square mile) of Wattenberg Field, Colorado. The time-lapse seismic data sets, after crossequalization, showed an acoustic impedance anomaly within the reservoir interval consistent with pressurization of the reservoir from surface operations. The spatial location of the anomaly is interpreted such that pressure compartmentalization exists due to faulting within the reservoir. A decrease in the acoustic P-impedance of up to 7% was observed from the baseline to the monitor survey in the reservoir interval. An increase in pore pressure owing to hydraulic fracturing was interpreted as the physical mechanism causing the greatest change in P-impedance. Hydraulic fracturing is highly dependent on local geology, and the integration of geoscience with parameter design is necessary for optimization. Time-lapse seismic reservoir monitoring can assist in documenting fault-related reservoir compartmentalization. The Colorado School of Mines Reservoir Characterization Project (RCP) undertook a monitoring project with Anadarko Petroleum Corporation (APC) in Wattenberg Field, Colorado. The Wishbone section is a one-square mile area containing 11 horizontal wells. Each well was fractured with multiple stages and completion design was varied from stage-to-stage. The completions parameters that varied were: well spacing, targeted formation, hydraulic fracturing volumes, pressure, rates, completion type, and number of stages.