Prediction of brittleness based on anisotropic rock physics model for kerogen-rich shale

• Published in: Applied geophysics Vol. 14; no. 4; pp. 463 - 479
• Main Authors: Qian, Ke-Ran, He, Zhi-Liang, Chen, Ye-Quan, Liu, Xi-Wu, Li, Xiang-Yang
• Format: Journal Article
• Language: English
• Published: Beijing Chinese Geophysical Society 01.12.2017; Springer Nature B.V; SinoPEC Key Laboratory of Shale Oil/Gas Exploration and Production Technology, Beijing 100083, China; SinoPEC Petroleum Exploration and Production Research Institute, Beijing 100083, China%China University of Petroleum(Beijing), State Key lab for Petroleum Resources and Prospecting, Beijing 102249, China; National Energy R & D center of shale oil, Beijing 100083, China; National Key Laboratory of Corporation of Shale Oil/Gas enrichment mechanism and effective development, Beijing 100083, China
• Subjects: Accuracy; Anisotropic rocks; Approximation; Brittleness; Clay; Coefficients; Computational fluid dynamics; Earth and Environmental Science; Earth Sciences; Effective medium theory; Feasibility studies; Fluids; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Kerogen; Lithology; Mathematical models; Mechanical properties; Model accuracy; Modulus of elasticity; Physical properties; Physics; Porosity; Predictions; Sedimentary rocks; Shale; Shear strength; Templates; shale; Rock physics modeling; brittleness; anisotropy
• ISSN: 1672-7975; 1993-0658
• DOI: 10.1007/s11770-017-0640-y

The construction of a shale rock physics model and the selection of an appropriate brittleness index ( BI ) are two significant steps that can influence the accuracy of brittleness prediction. On one hand, the existing models of kerogen-rich shale are controversial, so a reasonable rock physics model needs to be built. On the other hand, several types of equations already exist for predicting the BI whose feasibility needs to be carefully considered. This study constructed a kerogen-rich rock physics model by performing the selfconsistent approximation and the differential effective medium theory to model intercoupled clay and kerogen mixtures. The feasibility of our model was confirmed by comparison with classical models, showing better accuracy. Templates were constructed based on our model to link physical properties and the BI . Different equations for the BI had different sensitivities, making them suitable for different types of formations. Equations based on Young’s Modulus were sensitive to variations in lithology, while those using Lame’s Coefficients were sensitive to porosity and pore fluids. Physical information must be considered to improve brittleness prediction.