Formation Fracture Detection By The Sonic Shear Wave Logging - Laboratory Studies

A formation of low permeable material sometimes shows the high effective permeability at the fractured portion of the formation, and so the detection of the degree of fracture in the gas and oil reservoirs will serve the formation evaluation greatly. But the fracture detection technique has not been established yet. In our laboratory studies, it turns out that the transmission time of the torsional wave passing through a core sample with fracture is longer than that of the one without any fracture, although the core samples have the same physical properties and the equal length. C7n the other hand, this phenomenon can not be seen in the case of the longitudinal wave. In this report the authors show the results of the laboratory studies using the artificial cores with and without simulated fracture and the application of them to the well logging.