摘要 |
<p>The depth of a hydraulic fracture zone is determined by sensing and recording seismic wave motion at a series of spaced depths in a portion of a bore hole subjected to fracturing pressure during a shut-in period after the application of pressure while the fracture zone is unstable, and analyzing such motion recordings by eliminating components not attributable to the fracturing and discrete components from seismic sources attributable to the fracturing to determine an average background level of vertical and horizontal components, and comparing the average background level of the horizontal components of motion to the vertical component of motion to provide an indication of the presence or absence of fracturing at each depth.</p> |