Impacts of CO2-brine-rock interaction on sealing efficiency of sand caprock: A case study of Shihezi formation in Ordos basin

Large anthropogenic emission of CO2 causes earth temperature becoming higher and higher, which may lead to the melting of glaciers, the rising of sea levels, extreme weather and so on. An effective way of reducing emissions is to capture and sequestrate CO2 while not giving up the fossil fuels. Caprock seal is critical for CO2 long term storage. CO2-brine-rock interaction will change minerals composition and pore structure of both reservoir and caprock. This paper analyzes the variation trend of porosity and permeability due to CO2-brine-rock interaction in caprock of Shihezi formation in Ordos basin, where TOUGHREACT is used as simulation tool. Geological data of numerical model are acquired from core samples. Simulations show that minerals interaction plays an important role on sealing efficiency of caprock. Overall, porosity and permeability of caprock decrease with CO2 sequestration, which indicates that main mineral reaction in caprock is precipitation, and caprock sealing efficiency is enhanced. Cited as : Liu, B., Fu, X., Li, Z. Impacts of CO2-brine-rock interaction on sealing efficiency of sand caprock: A case study of Shihezi formation in Ordos basin. Advances in Geo-Energy Research, 2018, 2(4): 380-392, doi: 10.26804/ager.2018.04.03