Dynamic and Static Elastic Modulus Conversion for Shale in the Jiaoshiba Block, Fuling Area

Mechanical parameters of rocks can be obtained in two ways: well logging and laboratory experiments. The determination of dynamic mechanical parameters from well logging is much superior to those obtained through lab tests in terms of the data quantity, real-time performance and acquisition costs. Existing mechanical constitutive relationships are based on static parameters, so it is necessary to define the conversion between dynamic parameters and static ones. For this purpose, shale with intact bedding structures in the Lower Silurian Longmaxi Formation of Jiaoshiba Block, Fuling Area, was used to determine the impact of bedding angles, porosities and acoustic frequencies on the elastic modulus of shale. Research results showed that the bedding angles had the highest impact on the elastic modulus of shale. Accordingly, the conversion model between dynamic and static elastic modulus was established by using the correlation analysis method. Samples of shale taken from the same block were used to verify the results of the model. It was determined that the model had an average prediction error of less than 6%. The research results may provide an effective way to calculate dynamic and static elastic moduli for interbedded shales.