Reservoir Simulation of Reactive Processes
- Incorporate reaction kinetics, pore property information, and reservoir characterization into simulation.
- Create a reactive-transport reservoir simulation tool capable of modeling the conversion of kerogen to oil and gas and the transport of multiple phases under realistic geologic and reservoir conditions.
- Analyze how geologic heterogeneity impacts production from Utah oil shale resource.
Department of Energy, National Energy Technology Laboratory
In situ oil shale processing has the potential to minimize surface disturbance and process water requirements and to access deep, unmineable resources. Modeling the thermally-induced transformation of oil shale kerogen to liquid and gaseous fuels requires solving mass and energy conservation equations, which in turn requires physical understanding and models for reaction kinetics, multiphase fluid flow, geomechanics, and heat transfer. At reservoir scales, each of these submodels has continuously changing parameters that may affect model predictivity. Sparse geological data is an additional challenge as mineral and organic heterogeneity between and within resources may be important.
The STARS simulator developed by Computer Modeling Group has capabilities to represent thermal in situ processes. This project uses STARS to evaluate the sensitivity of production rates from oil shale to various in situ process parameters. Several sensitivity studies have been conducted to expose the interplay among physical parameters in STARS. Early results show that activation energies in a multi-step reaction scheme and relative permeability representations affect oil production more than heat of reaction.
Geological characterization of cores (Figure 1) in the Uinta Basin by another Institute for Clean and Secure Energy project, Developing a Predictive Geologic Model of the Green River Oil Shale, Uinta Basin, is providing a better picture of the organic and inorganic content of the reservoirs of interest and of their heterogeneity. This organic content information is being incorporated into process simulations.
Figure 1: U059 well Fischer Assay log.
Oil shale pyrolysis is an energy intensive process. This project has examined process variations and conceptualized new processes for minimizing energy use. A hybrid process that begins with pyrolysis and later utilizes the energy from coke combustion (produced by air injection) has a reduced energy consumption (Figure 2) compared to the original pyrolysis process. However, CO2 emissions increase due to coke combustion and carbonate decomposition.
Figure 2: Cumulative energy input for combined and pyrolysis only processes.