A New Method for Evaluating Shale Fracability Index and Its Application

Brittleness evaluation is the basis for shale fracability evaluation,and the brittleness index research has been limited to near-wellbore zone in foreign studies.In order to fully describe the shale fracability,a new integrated method of shale brittleness index evaluation was proposed in view of energy based on fracturing parameters.A comprehensive model of shale fracability index was established taking into account both geology and engineering parameters.Moreover,the normalization method was adopted to establish a new model of shale fracability index which was evaluated by the ratio of equivalent proppant volume to equivalent fracturing fluid volume.Field application showed that the calculated shale brittleness index is highly correlated to fracability index and post-frac gas production,and may be used to determine the preferred fraturing position for each stage;the new method is reliable and practicable.It can be recommended for promoting shale gas exploration and development in China.