The application of an integrated earth model in reservoir management of a CO₂ plume

The Illinois Basin - Decatur Project (IBDP) is a large-scale carbon capture and storage (CCS) demonstration project managed by the Midwest Geologic Sequestration Consortium (MGSC). IBDP is injecting 1 million tonnes of carbon dioxide (CO₂) in the Cambrian Mt. Simon Sandstone over three years at a rate of 1,000 tonnes per day. At the IBDP site the top of the Mt. Simon Sandstone is overlain by 100 m (300 ft) of tight silt and shale in the Eau Claire Formation that forms the primary seal that prevents possible migration of CO₂ into the overlying strata. Below the Mt. Simon Sandstone is a pre-Mt. Simon interval that is characterized by its poor reservoir quality. In the United States, the pore space storage rights are typically owned by the surface landowner. Therefore, it is imperative that CCS projects such as IBDP be able to estimate the size and movement of the CO₂ plume within the reservoir. An integrated earth model and subsequent reservoir flow simulations are the first steps to CO₂ plume management. An inversion of the 3D surface reflection seismic data was used to create a template for the distribution of the reservoir properties acquired from the well data. Inversion of the 3D seismic data produced two inversion volumes, an acoustic impedance (AI) cube, and a porosity cube. Wireline porosity logs were upscaled to the 3D model and then co-simulated with the seismic inversion porosity. Log permeability was upscaled to the simulation model and co-simulated with porosity. The resulting porosity and permeability fields were rescaled into the simulation grid which was discretized to achieve the required simulation accuracy while maintaining computational efficiency. The reservoir flow simulation based on the integrated earth model suggests that the CO₂ will follow the high permeability intervals and there will be very limited vertical migration of the CO₂. These flow simulations also will help with plume management in a new planned injection well near the IBDP project site which will be perforated at higher intervals in the Mt. Simon Sandstone than those in the original injection well.