Feasibility Research Mantle-derived Carbon Dioxide Infilling And Oil Displacement

Based on fluid inclusion geology and stable isotope geochemistry, coupled with petrology andresearch method such as supercritical fluid, this paper conducts a research on filling oil displacementmechanism of mantle-derived CO2fluid in Changling depression, southern Songliao Basin. Thescientific problems to be solved are (1) the injection sequence of mantle-derived CO2and gasoline and(2) the interaction mechanism of mantle-derived CO2and oil-gas.Through the study of petrological characterization, we conclude that the diagenetic sequence ofdawsonite-bearing sandstone, in turn, is percolation clay-authigenic kaolinite (secondary overgrowthquartz)-early calcite-dawsonite-late calcite-ankerite, in addition, it is found that asphalt exists withclastic particles, dawsonites and calcites, indicating that the formation of asphalt is earlier than that ofdawsonite. According to the homogenization temperature of fluid inclusions testing, burial-thermalhistory curve and illite K-Ar age dating, in combination with volcanic and tectonic activity, and othergeological factors, it is inferred that the filling time of CO2is later than that of oil-gas.Through the analysis on the theory of nature gas (CH4) displacement and oil driving water, weestablished the model of mantle-derived CO2-bearing fluid infilling and displacement. The key of themodel is whether CO2could form sufficient driving force. The fourth-member of Quantou Formationreservoir in Changling sag of southern Songliao basin is match with the model, and we found the mixedlayers of mantle-derived CO2and oil-gas, moreover, the infilling of oil and gas was earlier than that of CO2. According to the geological conditions in the study area, we analyzed the driving and resistantforce as well as the parameters which related to them, such as original CO2density, interfacial tension,pore throat radius and CO2column height. It concluded that the buoyancy created by mantle-derivedCO2and crude oil is enough to breakthrough the migration resistance (i.e., capillary resistance). It canbe proved that mantle-derived CO2plays a promoting role on the migration of oil and gas inperspectives on physics and mathematics.