A Micro-scale Method for Predicting the Mechanical Properties of Reservoirs with Strong Heterogeneity

Accurate acquisition of rock mechanics parameters for unconventional reservoirs is a very important work in fracturing design. Glutenite is a typical strongly heterogeneous reservoir. The rock mechanical properties of gravel and matrix in glutenite are quite different due to the differences in mineral composition. However, due to the limitation of experimental conditions, the research on mechanical parameters of gravels is relatively lacking. This article establishes a new micro-scale method for measuring the mechanical parameters of irregular gravels, and this method compensates for the shortcomings of conventional mechanical instruments that cannot measure the mechanical parameters of non-standard samples such as gravels. The load-displacement curve of each gravel is measured by the micron indentation instrument, and the microscopic Young’s modulus and microscopic fracture toughness of gravels are calculated by the relevant formulas. Based on the experimental statistical data, a converting method is used to obtain the macroscopic Young’s modulus and macroscopic fracture toughness of gravels. Taking the glutenite reservoir in the Western China as an example, the macroscopic Young’s modulus of gravels is calculated to be 9824 to 17014 MPa, and the fracture toughness ranges from 0.777 to 1.846 MPa·m^0.5. The results show that the mechanical parameters of gravels are generally stronger than those of matrix. The method established in this paper can not only be applied in glutenite reservoirs, but also provides a new idea for determining the distribution of rock mechanical parameters in all heterogeneous reservoirs. Moreover, this method has low cost, less time consumption, and has strong promotion value.