New method for discrimination of the degree of fracture development using conventional log data

Study on the degree of fracture development in fractured formation is very important. A new method for discriminating it using conventional log data is put forward. Formation conductivity and the features on resistivity curve within the interval of fractured formation increase due to the presence of fracture. Thus three parameters that reflect the degree of fracture development within shallow, intermediate and deep radial investigation depths are extracted. They are SR/Rxo, SR2/(Rxo·RI) and SR3/(Rt·RI·Rxo). Resistivity of non-fractured formation and the criteria for fracture discrimation with the three parameters are determined for model samples. Then they are used to discriminate the degree of fracture development for non-model samples. This method is used in fractured sandy-conglomerate formation, Xinjiang Oilfield. Case history shows the result is good.