Abstract

A study, entitled “Wabamun Lake Sequestration Project” or “WASP, ” was performed to evaluate large-scale CO2 storage opportunities in the Wabamun area including potential risks. The project examined the feasibility of storing 20 megatons (Mt) of CO2 per year over 50 years. This scale is one order of magnitude larger than the typical benchmark (1 Mt/year) used in academic research and commercial projects that are currently in place or under review. The study was conducted by a group of researchers from several universities as well as industry consultants. This study presents an overview of the reservoir modeling part of this study, which the authors were responsible for. The main objectives of the reservoir modeling for WASP project were as follows: (1) estimation of storage capacity (traditionally, this value is projected based on the available pore space, but we have an additional practical consideration: the maximum amount one can inject within short period of time [~50 years] and within a localized injection area [~30 km × 90 km]), (2) investigation of CO2 plume movement and pressure distribution during and after injection including the effect of formation dip angle on the plume shape and its migration, (3) investigation of the long-term fate of injection associated with free phase CO2 (risks of leakage) and aquifer pressurization (possible geomechanical changes and related phenomena), (4) investigation of the phase behavior of H2S initially available and dissolved in brine during CO2 sequestration process. The WASP reservoir modeling study mentioned above led to a few important findings. The most important one is that, when CO2 is being injected into a sour aquifer, initially dissolved H2S will release into the expanding CO2 plume and accumulate at the leading edge of the plume. Also, the large-scale injection scheme (20 Mt/year), which requires multi well injectors, provides very different pressure response compared to a one well (1 Mt/year) scenario.