Effect Of CO₂-water Reaction On Mineralization And Sequestration Mechanism Of Sandstone Reservoir

The greenhouse effect induced by the increase of CO₂ content in the atmosphere has received eager attention from the international community.At present,the sequestration of CO₂ in deep saline aquifers is an internationally recognized method of storage,and sandstone reservoirs are the largest reservoirs of geological reserves.Therefore,the effect of CO₂-salt water-rock interaction caused by the CO₂ injection into the aquifer on the mineralization and storage mechanism of the sandstone reservoir plays a crucial role in the geological storage of carbon dioxide.So far,there have been few studies on sandstone reservoirs.Therefore,this article takes the reservoir sandstones of Liujiagou Formation and Shiqianfeng Formation,which were adopted in CCS demonstration project of Shenhua,Inner Mongolia,as the research object,Using CO₂-water rock reaction experiments,experimental tests and numerical simulations,the effects of CO₂-water-rock reactions on the mineralization and storage mechanism of sandstone reservoirs under actual reservoir conditions were studied,and the following conclusions were drawn:（1）When CO₂ is injected into the aquifer,the calcite in the sandstone reservoir of the Liujiagou Formation continues to generate,and the higher the temperature,the more the amount of calcite produced,and other carbonate minerals and chlorite;The surface of the sandstone of the Shiqianfeng Formation did not show insoluble carbonate minerals,but mineral deposits such as bauxite,chlorite and albite occurred,It also shows that CO₂ can exist in rock formations in the form of mineral sequestration,but higher temperature conditions may be needed.（2）The mineralization reaction of the sandstone reservoir in the study area has a close relationship with the temperature change.In terms of mineral dissolution,the higher the temperature,the more severe the dissolution of feldspar,quartz and clay minerals;In terms of mineral production,calcite generation is positively correlated with temperature,and chlorite is more conducive to production at low temperatures.（3）After CO₂ is injected into sandstone reservoirs,the porosity of sandstone reservoirs in the Liujiagou Formation is gradually increasing,and the reservoir conditions are optimized,which is more conducive to the geological storage of CO₂.The porosity of the sandstone reservoirs in the Shiqianfeng Formation shows a decreasing trend,and self-sealing occurs.This provides a certain basis for microscopically explaining the possibility of an optimal reservoir transition.（4）The numerical simulation results are basically consistent with the experimental results,demonstrating the experimental results,supplementing them,and enhancing the reliability of the experimental results.