Abstract: Formation fracturing is the most common way to develop low-permeability oil and gas reservoirs so as to increase oil and gas output. The vertical extension of fractured fractures in reservoirs determines the formation testing results. However, no effective method has been found to examine fractured fractures. Generally speaking, dipole sonic logging is applied in measuring open-hole wells to evaluate formation anisotropy and identify gas zones. On the basis of analyzing the dipole sonic logging mechanism, dipole sonic logging is conducted in casing to examine the expanded height of fractured fractures and to guide the analysis of formation testing results. Good application results have been obtained from correctly identifying reservoirs. The new technique is proved to be an effective way to evaluate fractured results. What's more, it allows more application of logging data to engineering examination.

Key words: dipole sonic wave, fracturing, shear wave, fracture