Elastic parameter inversion of Longmaxi Formation shale based on the least squares method

• Published in: Arabian journal of geosciences 2021-04, Vol.14 (7), Article 607
• Main Authors: Gao, Kepan, Liu, Xiangjun, Xiong, Jian, Liang, Lixi
• Format: Article
• Language: English
• Subjects: Accuracy; Acoustic velocity; Acoustics; Anisotropy; Data logging; Direction; Earth and Environmental Science; Earth science; Earth Sciences; Elastic anisotropy; Elastic waves; Least squares method; Logging; Parameters; Review Paper; S waves; Sedimentary rocks; Shale; Shales; Silurian; Sound transmission; Stratification; Velocity; Wave velocity
• ISSN: 1866-7511; 1866-7538
• DOI: 10.1007/s12517-021-06657-8

Elastic parameters are important parameters in the study of shale anisotropy, exploration, and development, and their accuracy is of great significance. In this study, shale in the lower Silurian Longmaxi Formation of southeastern Chongqing was investigated by obtaining the acoustic velocity of the partial bedding angle through an acoustic transmission experiment based on the elastic wave theory of the VTI medium and the least squares method, thus establishing a shale elastic parameter inversion method for improved accuracy. Results found that (1) the stratification angle was negatively correlated with the wave velocity; (2) velocity results calculated using the inversion-obtained elastic parameter were consistent with the measured results, with a maximum relative error of less than 1.52%, demonstrating that elastic parameters obtained by the proposed inversion method are valid; and (3) Longmaxi Formation shale has strong anisotropy, with the most significant direction of shear wave splitting being the direction in which the bedding angle is 0°. The results of this study provide a working foundation for using acoustic logging data to more accurately obtain the elastic parameters of shale and to study shale anisotropy characteristics, which have important theoretical value and practical significance.