Reactive transport modeling for CO2 geological sequestration

Abstract

Abstract. One way to reduce carbon dioxide (CO 2 ) releases to the atmosphere, is to capture it from power plants and then inject it into deep geological formations.Understanding water-gas-mineral reactions is the core of assessing the long term storage and risks in geological sequestration. Because of various limitations of laboratory and field tests, reactive transport modeling has been one important supplementary or independent tool to study the water-gas-mineral reactions at different components of geological sequestration. In this paper, we reviewed the applications of reactive transport modeling to three aspects of CO 2 geological sequestration: the behavior of CO 2 in storage formation, the storage security issues related to caprock integrity or wellbore cement degradation, and the change of the shallow groundwater in response to the potential leakage of CO 2 . Key finding are summarized and further research needs are identified. The lack of the detailed mineralogical composition information at the storage formation, caprock and overlying aquifers is currently the first obstacle for quantitative prediction of geochemical evolution. The thermodynamic properties of relevant minerals under high temperature and pressure have to be refined. Reliable reaction rates of minerals dissolution/precipitation at field are still the bottle neck of the calculating the long term mineral trapping of CO 2 . Issues related to relatively fast reactions such sorption and ion exchange need special attention when the impact of CO 2 leakage on shallow groundwater was evaluated. The role of organic compounds in water-gas-mineral reactions needs further study.2

Impacts of stratum dip angle on CO2 geological storage amount and security

“…In the process of CO 2 geological storage, large‐scale CO 2 injection into a deep geological reservoir is a multifield coupling process that includes seepage, temperature, chemical, and stress fields. This involves complex multiphase flow and solute transport, as well as formation fluid and rock mineral chemical reactions . Numerical modeling is one of the most effective tools and methods for studying CO 2 ‐related physical and chemical processes in deep formations .…”

“…It can cope with long‐duration CO 2 geological storage problems, and make up for space and time restrictions experienced by laboratory experiment and field testing. Among such models, TOUGH2, a non‐isothermal multiphase flow simulation software, has been widely used in the United States, Europe, Australia, Japan, and China . A user‐interface computer (visualization) code, TOUGHVISUAL, has been developed for TOUGH2 and TOUGHREACT to deal with the modeling of complex geological conditions .…”

Influence of geochemical processes on the geomechanical response of the overburden due to CO2 storage in saline aquifers

“…Large volumes of fluid or CO 2 injection into a geologic reservoir changes fluid pressure in and around the reservoir. Geochemical reactions that occur during CO 2 injection and post-injection periods may have an influence on resident brine, reservoir rock, and immediately overlying caprock layers (Hangx et al, 2010a,b;Wertz et al, 2013;Xu et al, 2011). These geochemical interactions may change formation properties and could lead to a different pressure and ground response.…”

Mechanistic Modeling of Low-Salinity Waterflooding Through Coupling a Geochemical Package With a Compositional Reservoir Simulator

“…Although waterflooding has been used as a secondary-oil-recovery method for nearly 150 years, it was not until relatively recently that it has begun to be thought of as a chemical as well as a physical process where the ionic composition of the brine can affect oil recovery by changing wettability (Tang and Morrow 1996;Yildiz and Morrow 1996). Perhaps the simplest example of this is the discovery that reducing the salinity of the injected water can improve waterflood recovery and that salinity should be controlled along with the volume of water injected.…”