渤海湾盆地深部CO2来源与热液活动对储层的改造作用OA

The Bohai Bay Basin is one of the important hydrocarbon-bearing basins in eastern China,and its com-plex reservoir-forming characteristics are closely related to modification by deep CO2 injection and CO2-rich hydro-thermal activity.A comprehensive analysis of the correlations among CO2 content,δ13CCO2,and R/Ra indicates that the CO2 in the basin is primarily derived from CO2 released by deep mantle-derived magmatic activity.Statistical a-nalysis of CO2-bearing fluid inclusion data reveals a bimodal pattern in homogenization temperatures,suggesting that the study area reservoirs have undergone multiple episodes of hydrothermal modification.Additionally,this study summarizes various lines of evidence from petrology-mineralogy and geochemistry regarding the impact of hy-drothermal activity on reservoirs.Petrological-mineralogical evidence includes typical hydrothermal minerals such as ankerite,pyrite,chlorite,and dawsonite.In regions like the Bozhong Depression,Jiyang Depression,calcite in reservoirs exhibits lower oxygen isotope values and positive Eu anomalies in rare earth elements,indicating a hydro-thermal origin.The modification of reservoirs by deep hydrothermal fluids shows significant spatial differences.Near areas of deep hydrothermal activity,CO2-rich hydrothermal fluids significantly improve reservoir porosity and permeability through dissolution and thermal baking effects,with the peak of dissolution-induced improvement oc-curring at the leading edge of hydrothermal activity.In contrast,in areas far from deep hydrothermal activity,pre-cipitation and cementation of authigenic minerals(e.g.,dolomite,calcite,quartz)lead to reduced porosity and permeability.