DOE OSTI2014
This project is part of a larger project co-funded by the United States Department of Energy (US DOE) under cooperative agreement DE-FE0002068 from 12/08/2009 through 9/31/2014. The study is to evaluate the potential of formations within the Cambro-Ordovician strata above the Mt. Simon Sandstone as potential targets for carbon dioxide (CO2) sequestration in the Illinois and Michigan Basins. This report evaluates the potential injectivity of the Ordovician St. Peter Sandstone. The evaluation of this formation was accomplished using wireline data, core data, pressure data, and seismic data acquired through funding in this project as well as existing data from two additional, separately funded projects: the US DOE funded Illinois Basin – Decatur Project (IBDP) being conducted by the Midwest Geological Sequestration Consortium (MGSC) in Macon County, Illinois, and the Illinois Industrial Carbon Capture and Sequestration (ICCS) Project funded through the American Recovery and Reinvestment Act (ARRA), which received a phase two award from DOE. This study addresses the question of whether or not the St. Peter Sandstone may serve as a suitable target for CO2 sequestration at locations within the Illinois Basin where it lies at greater depths (below the underground source of drinking water (USDW)) than at the IBDP site. The work performed included numerous improvements to the existing St. Peter reservoir model created in 2010. Model size and spatial resolution were increased resulting in a 3 fold increase in the number of model cells. Seismic data was utilized to inform spatial porosity distribution and an extensive core database was used to develop porosity-permeability relationships. The analysis involved a Base Model representative of the St. Peter at “in-situ” conditions, followed by the creation of two hypothetical models at in-situ + 1,000 feet (ft.) (300 m) and in-situ + 2,000 ft. (600 m) depths through systematic depthdependent adjustment of the Base Model parameters. Properties for the depth shifted models were based on porosity versus depth relationship extracted from the core database followed by application of the porosity-permeability relationship. Each of the three resulting models were used as input to dynamic simulations with the single well injection target of 3.2 million tons per annum (MTPA) for 30 years using an appropriate fracture gradient based bottom hole pressure limit for each injection level. Modeling results are presented in terms of well bottomhole pressure (BHP), injection rate profiles, and three-dimensional (3D) saturation and differential pressure volumes at selected simulation times. Results suggest that the target CO2 injection rate of 3.2 MTPA may be achieved in the St. Peter Sandstone at in-situ conditions and at the in-situ +1,000 ft. (300 m) depth using a single injector well. In the latter case the target injection rate is achieved after a ramp up period which is caused by multi-phase flow effects and thus subject to increased modeling uncertainty. Results confirm that the target rate may not be achieved at the in-situ +2,000 ft. (600 m) level even with multiple wells. These new modeling results for the in-situ case are more optimistic than previous modeling results. This difference is attributed to the difference in methods and data used to develop model permeability distributions. Recommendations for further work include restriction of modeling activity to the in-situ +1,000 ft. (300 m) and shallower depth interval, sensitivity and uncertainty analysis, and refinement of porosity and permeability estimates through depth and area selective querying of the available core database. It is also suggested that further modeling efforts include scope for evaluating project performance in terms of metrics directly related to the Environmental Protection Agency (EPA) Class VI permit requirements for the area of review (AoR) definition and post injection site closure monitoring.