3D Relocation Errors of Microseismic Events by Surface and Borehole Receivers for Shale Gas Stimulation

Abstract

SUMMARYMicroseismic monitoring and mapping of induced hydraulic fractures (frac) is an important tool in unconventional oil and gas exploitation. It is a key technology for completion evaluation which allows for continuous improved frac design, frac effectiveness, and ultimate resources recovery estimation and development. Formation evaluation tools provide accurate measurements of the target formation's petrophysical and mechanical properties proximal to the borehole only, distal to the borehole though, Microseismic monitoring can be a useful tool to monitor the formation's response to the frac. Shale response to hydraulic stimulation can be estimated mainly by the local density and pattern of hypocentres. Linear trends of microseismic event and their associated focal mechanisms may highlight the reactivation of faults due to hydraulic stimulation, while the location of events outside the target formation may suggest a need for future Improvements to the completion/ stimulation plan, and in some cases, restimulation. However, errors in the hypocentre locations may convert clear trends into "fuzzy" clouds, hampering our understanding of how the simulation interacted with the formation. The accuracy of hypocentral coordinates of micro-earthquakes is critical for understanding and proper planning for the hydraulic stimulation jobs of a shale play.