Coupled CFD–DEM numerical modelling of perforation damage and sand production in weak sandstone formation

A coupled microscopic simulation method was implemented to investigate the bond breakage behaviour during perforation and sand production in a weak cemented sandstone. A new contact bond model was implemented in the open-source program CFDEM to simulate a large cylindrical sample of one hundred thousand numerical particles using a high-performance computer (HPC) system. The coupled simulation of the particle–fluid phases and the information exchange between them required intensive computational power and highly efficient parallelization algorithms, yet it provided the detailed information on the distribution of bond and bond breakage, new contact formation, particle migration and the associated change in the internal porosity across the sample. The perforation process was found to create a damage zone that contained a compacted core of unbonded particles. The compacted core expanded quickly under fluid flow condition and released its particles to migrate towards the perforation tunnel. Small particles were produced first from the perforation damage zone, while fewer particles of larger sizes were produced later in an overall transient sand production phenomenon.