Hierarchical Coarsening of Simulation Model for In-Situ Upgrading Process

Oil shales are sedimentary rocks containing organic matter in form of kerogen which account for more than 5 trillion barrels of oil in place according to Birol (2010); therefore, oil shale production represents a plausible solution for the constant increasing demand for hydrocarbons. In this work, first we describe the model for chemical decomposition of kerogen. The prototype of the model is implemented in ADGPRS. The model is based on the most recent understanding of pyrolysis process and contains very precise descriptions of coupling chemical kinetics to heat and mass transport. Due to the high number of species, variations of porosity as consequence of the transformation of solid species into fluid products and complex multi-scale structure of porous media, the simulation performance of the high-fidelity model is limited. As the second step of this work, we introduce a hierarchy of coarser models to improve the run-time of forward solution without significant reduction in accuracy. We applied coarsening in time, space, and chemical representation, and quantify errors introduced at each coarsening level. In conclusion, we provided recommendations for large scale modeling of in-situ upgrading process.