Fracture survey on the base of full-wave numerical simulation of wave propagation and maximum likelihood method

To improve the efficiency of hydraulic fracturing to need a good knowledge of the mechanical characteristics of borehole environment. One of these characteristics is a dominant direction of fractures including some distance from the well, wherever can spread fracture. The authors propose to extend the possibilities of the technology "Full-Wave Location of events" (FWL), which was previously used with the "explosive" source type up to the "tensile crack" source type confining ourselves to the vertical crack. The paper describes the method of events location, forming the source of "tensile-crack", also presents the result of the technology application to the real data.
Materials and methods
microseismic records, velocity model ofthe VSP, method of full-wave numerical simulation, maximum likelihood method
Results
Based on a set of microseismic events identified at the recovering of the amplitude processing stage, determinated areas of greatest concentration of events and is detected the dominant direction of their cracks and plotted the rose of directions of cracks for the entire observation period (look at Fig. 2). Sufficiently clearly are identified basic directions of cracks~ 1600 and ~ 220, suggesting the statistical significance of the results.
Conclusions
The maximum likelihood method is theoretically the most informative andnoise-immunity method for signals recovery.The article presents an approach basedon the special case of using the method of maximum likelihood to recover the amplitudes of microseismic events corresponding to different azimuthal orientation of the vertical opening/closing of the crack.Determination of fractures using a full-wave numerical simulations and maximum likelihood method requires considerable computing resources, but using for the calculation of clusters of GPUs makes these calculations is technically possible and economically accessible even now.