Downhole Microseismic Data Processing - Consistency of Locations, Source Mechanisms and Stress State
Z. Jechumtálová, F. Chu, J. Rong, J. Procházka and L. Eisner
Event name: 78th EAGE Conference and Exhibition 2016
Session: Micro and Passive Seismic Event Detection and Analysis (A)
Publication date: 31 May 2016
Info: Extended abstract, PDF ( 1.17Mb )
Price: € 20
We present results of processing of microseismic events induced by hydraulic fracturing and detected by dual downhole monitoring arrays in nearly optimal geometry providing unique insight into hydraulic fracturing. We detected and located microseismic events, determined their magnitudes, source mechanisms and inverted stress field orientation. Event locations were forming a highly linear trend above the stimulated intervals. The source mechanisms were computed only for higher quality events which were detected on sufficient number of receivers to obtain reliable result. All detected source mechanisms were dip-slip mechanisms with a steep and nearly horizontal nodal plane. The source mechanisms represent shear events, non-double-couple components were very small consistent with the noise level in data and velocity model uncertainties. The strikes of inverted mechanisms corresponding to the nearly vertical fault plane are (within the error of the measurement) identical with the strike of the location trend. Finally, regional principal stress directions were inverted from the source mechanisms. The least principal stress σ3 is perpendicular to the strike of the trend of the locations, indicating that the hydraulic fracture propagated in the direction of maximum horizontal stress.