Oil Shale In Situ Production Using a Novel Flow-Heat Coupling Approach.

Abstract

Oil shale development, a significant global energy concern, involves the pyrolysis of kerogen, a process that can heat and contaminate groundwater with pyrolysis products. To address these challenges, this study introduces the ambient-temperature gas in situ heating (ATGIH) method as an alternative to traditional techniques. The ATGIH method establishes a low-temperature gas barrier to prevent water infiltration into the production zone by placing heating holes between the injection and production wells. The effectiveness of the ATGIH method in mitigating groundwater contamination during oil shale development is demonstrated through thermochemically coupled reservoir simulations. The study further discusses how gas injection enhances the flowability of mobile oil and gas phases into production wells and how controlling the Dykstra-Parsons coefficient, a measure of heterogeneity, can mitigate gravity segregation and aggregate viscous fingering issues. Our results show that well spacing is a critical factor in designing oil shale development, with a larger spacing resulting in higher energy efficiency but lower oil recovery rates. Furthermore, the study reveals that porosity decreases while permeability increases during pyrolysis due to thermal cracking and pore structure changes. It also highlights that heterogeneity-induced issues can be alleviated by increasing the correlation length to make the system more homogeneous. Therefore, the ATGIH method represents a key innovation in oil shale development, offering a solution that mitigates groundwater contamination while improving the energy efficiency.