Microseismicity constitutes the only practical tool we have of determining the likely
location of flow paths in the reservoir, which is important for targeting wells to
obtain satisfactory linkage between wells. However, 3-D maps of microseismic
activity define regions where pore pressure has become elevated and thus is
hydraulically connected to the injection well. This does not necessarily imply that
the microseismically-illuminated regions contain paths that support significant flow.
That is, microseismic structures are not necessarily hydrologically-significant
structures. This issue of the interpretation of microseismic structures is central to
the development of EGS/HDR systems. In this presentation I will examine some case
histories where wells have been targeted to pass through dense microseismicity, and
evaluate the success in intersecting flowing structures. I will also suggest ways of
improving the ability to detect hydrologically-significant structures from
microseismic observations.
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