Study of Micro-Parameters of DEM Model on the Laboratory Experiment Results Obtained from Poorly Cemented Sandstone

Borehole convergence during or after drilling is one of the primary indicators of borehole instability. Early recognition of borehole instability is critical in achieving successful and timely completion of drilling operations and for borehole exploitation. A series of numerical simulations was conducted to investigate the borehole convergence of poorly cemented sandstones using the Discrete Element Method (DEM). Rectangular 2-dimensional Particle Flow Code 2D (PFC2D) models were generated to study the effect of contributing micro-parameters such as stiffness ratio, friction angle, friction coefficient and effective modulus on the behaviour of poorly cemented sandstone subjected to triaxial compression tests. A good agreement between the calibrated numerical models and the experimental data obtained from the laboratory was observed. The results showed that the stiffness ratio was found to be a dominant factor in calibrating the numerical model, and the friction coefficient was the most influential micro-parameter.