Modeling and reservoir simulation of CO2 storage in the Tensleep Formation: Surrogate models based on the Teapot Dome

This thesis describes effects of fracture-matrix flow on the feasibility of storing CO2 in saline aquifers. The Teapot Dome Tensleep Sandstone was used as a surrogate for aquifers in the Tensleep or similar formations by mapping average properties obtained from a database corresponding to the Tensleep Sandstone.;A 3D geologic reservoir model of the Tensleep Sandstone was developed using geophysical, geological, and engineering data, i.e. reservoir image map, well tops, well-log and core analysis data. A fluid flow dynamic model of the Tensleep Sandstone, based on a 3D geologic model (static model), was built to study CO2 migration and storage volume. To limit the range of fracture properties in dual-porosity/permeability models, history matching of field-wide primary production data was conducted. Several combinations of fracture permeability and fracture spacing values were tested to match historical cumulative water and oil production at the Teapot Dome corresponding to the Tensleep Sandstone at that location. The history-match was shown to be more sensitive to fracture permeability than to fracture spacing.;Effects of the presence of natural fractures in the double porosity system were evaluated by comparing the amount of CO2 trapped by each trapping mechanism in single-porosity, dual-porosity and dual-permeability models. Results show that dissolution trapping is more important in dual-porosity/permeability models compared to that in single-porosity models. Results show hydrodynamic trapping is only favorable in dual-porosity/permeability media depending on the balance between the rate of dissolution and flow velocity. In addition, effects of different aquifer properties and injection strategies on immobilization of CO2 by residual and solubility trapping inside the fractured saline aquifers were investigated. Finally, despite the fact that the fracture-matrix flow promotes CO2 movement and contact with brine, naturally fractured aquifers should be considered as potential carbon storage pilots only if effects of the fracture-matrix flow coupling are quantitatively well understood.;A computer experimental design focused on analyzing effects of depth (temperature), porosity, and absolute permeability on gas trapping were conducted in six models: single-porosity models with and without solubility, dual-porosity models with and without solubility, and dual-permeability models with and without solubility. Results show that fractures and solubility can affect CO2 storage volume and trapping efficiency. Compared to single-porosity models, CO2 trapping efficiency is much lower in dual-porosity/permeability models. Models with the solubility factor are more efficient in trapping CO 2. Since naturally fractured deep saline aquifers are distributed worldwide, this study might be viable and practical in analyzing the feasibility of CO 2 storage and evaluating the effects of aquifer properties and injection strategies on storage efficiency in naturally fractured aquifers.