PFC3D Modeling of Rock Fragmentation by Pressure Pulse

Unconventional hydrocarbon resources like tight oil make up a large fraction of the global hydrocarbon reserve. Tight oil exists in low permeability formations that require permeability enhancement for economic production. Chemically induced pressure pulses are being investigated as an alternative to hydraulic fracturing to enhance the permeability of these reservoirs. A numerical investigation of rock damage and fragmentation due to a chemically induced pressure pulse around a well is carried out using Itasca’s discrete element code PFC3D. Itasca’s material-modeling support package is used to create synthetic rock specimens that are subject to explosive loading. Python scripting, which is embedded in PFC Furtney et al.(Proceedings of the fourth Itasca symposium on applied numerical modeling (Lima, Peru). Minneapolis, Itasca International, Inc, [1]), is used to apply the gas pressure and generate the visualization. Qualitative features of the laboratory experiments matched with PFC3D results. Fragmentation of a block specimen expected at a range of peak pressure and pressure rise time values was analyzed. As expected, and as observed in the experiments, the number of radial fractures increases as the rise time decreases. The intensity of the fracturing and near hole crushing increase as the peak pressure increases. Permeability change is estimated from the predicted fracturing. Insights gained from numerical modeling have helped the development of the chemical stimulation methodology.