Effect of particle breakage caused by mechanical compaction on pore characteristics of sandstone: A DEM numerical simulation study

Mechanical compaction is an important diagenesis of sandstone. Particle breakage commonly occurs during mechanical compaction, and plays a significant role in controlling the physical properties of the sandstone reservoir. However, existing experimental and numerical simulation methods have limitations in simulating mechanical compaction when considering particle breakage. In this study, a discrete element method (DEM) is purposed, which takes the maximum contact stress as the criterion of particle breakage and realizes particle breakage by particle cutting. Nine sets of numerical simulations were carried out with different breakage thresholds of reference particle (diameter = 6mm) and Weibull modulus. The parameters were calibrated according to the experimental data in published literature. On this basis, the compaction simulations of coarse sand with and without particle breakage were carried out, and the simulated vertical stress was 50Mpa. The results show that particle breakage caused by mechanical compaction significantly controls the porosity and pore structure. When the vertical stress reached 50 MPa, compared to the simulation results without considering particle breakage, the porosity difference rate caused by particle breakage was 4.63%; the radius difference rates of pores and throats were 2.78% and 6.8%, and the number difference rates of pores and throats were 4.95% and 8.74%, respectively. The simulation method can be used as an important technique in the study of sandstone diagenesis and is significant for revealing the formation process and mechanism of oil and gas reservoirs.