Optimization of Geological Carbon Sequestration in Heterogeneous Saline Aquifers through Managed Injection for Uniform CO2 Distribution

Abstract

Abstract To mitigate continued release of CO2 from anthropogenic sources, underground storage of carbon dioxide (CO2) is accepted worldwide as a promising and well-established technology. Due to increased concerns on CO2 emissions, there has been foremost importance in recent years on the development and establishment of safe, technologically feasible and economic geological carbon sequestration (GCS) technology. GCS has been practiced widely as a potentially practical climate change mitigation decision. For this purpose to dispose large amount of CO2 in economic and safe fashion for long term periods, deep ocean and geologic sequestration are considered viable options. Geologic sequestration is a potential technology to decrease released CO2 into the atmosphere through capturing CO2 from hydrocarbon emissions, transporting compressed CO2 from the source to the field, and injecting and storage of CO2 into the underground formation. While injecting CO2 into the formation, residual gas trapping and solubility trapping are the most important trapping mechanisms for CO2 storage in saline aquifers. The lack of information about the geological formation results in uncertainties in specifying the storage capacity of the formation and the safety of sequestered CO2 caused by leakage. These uncertainties influence the sequestration capacity and CO2 plume migration. Moreover, the sequestration efficiency is highly dependent on the injection strategy which includes injection rate, injection pressure, type of injection well employed and its trajectory. The goal of GCS is to maximize the sequestration capacity and minimize the CO2 plume migration by optimizing the GCS operation before progressing with its large scale deployment. Hence the objective of CO2 sequestration is to achieve a more uniform sweep efficiency and more extensive CO2 sweep of the geological formation for a fixed amount of injected CO2. To accomplish this objective, we propose a novel formulation for CO2 sequestration optimization problem to promote uniform distribution of CO2 in geological formation through minimizing the gas saturation differences in cells with the same distance to CO2 injection wells.