Research On The Factors Influencing Porosity In The Process Of CO₂ Storage In The Saline Aquifer

Nowadays,global warming has become an unavoidable new problem for all mankind,and CO₂ gas is considered by scientists as one of the main factors leading to global warming.Therefore,the control of increasing atmospheric CO₂ content has become an indispensable requirement.For the control and mitigation of CO₂,Carbon Capture,Utilization and Storage?CCUS?was proposed.Among them,CO₂ storage is a very economical link,and many countries have already carried out related projects.The saline aquifer is considered to be a potential location for buried formations.This paper explores the effect and evolution of geochemical reaction on porosity when the CO₂ is dissolved and buried.This article mainly discusses five different types of deep saline aquifer burial mechanisms,and a series of geochemical reactions that may occur during the burial process and the impact of CO₂-saline-rock interaction on porosity.The importance of porosity is derived from the commonly used CO₂ storage prediction methods,using CMG software for numerical simulation,using physical parameters and three main rock minerals preset 21cases to simulate the main impact on dissolved storage,CO₂ and brine water Rock interaction and porosity changes,and a new simple method for calculating the porosity changes after the reaction is proposed.?1?The reservoir pressure increases and the amount of dissolved CO₂ decreases.As the reservoir temperature increases,the solubility of CO₂ in brine decreases with increasing temperature.The salinity of the reservoir increases,and the amount of dissolved CO₂decreases as the salinity increases.As the injection rate increases,the amount of CO₂ in contact with the brine increases and the distribution increases,so the dissolution rate increases.?2?The increase in pressure and temperature will accelerate chemical reactions such as the formation of calcite precipitates in the dolomite,thereby reducing the porosity faster;the higher the salinity,the more free ions,and the greater the impact on the porosity.?3?Dolomite is one of the most important minerals in the system.After dissolution,it will produce a certain amount of calcite,which increases the porosity of the reservoir.The volume fraction of oligoclase has a certain effect on the reservoir but less than the dolomite.In terms of geochemical changes,dissolution of dolomite is the largest source of porosity.It was found that the physical properties of the formation,such as temperature,pressure,and brine salinity,have a certain effect on mineral dissolution and precipitation.The results of this study may have practical significance for the successful injection of CO₂and the improvement of oil and gas/geothermal production in low permeability formations,and may provide a new basis for the selection of reservoirs and reservoirs.