Design Of Gas Injection Pilot Scheme To Enhance Oil Recovery In Low Permeability Reservoirs

This thesis first summarizes the importance,classification and development characteristics of low permeability reservoirs through sufficient literature research.Based on summarizing the mechanism of improving the recovery of different types of injected gas,the advantages and limitations of the development of low permeability reservoirs and the application status of gas injection and flooding technology are summarized.Which laid a theoretical foundation for the development of low permeability WX Reservoir for gas injection.After simulating the fluid phase of reservoir by numerical simulation software,the Minimum Miscible Pressure?MMP?of different gases with crude oil at the reservoir temperature was predicted by simulating the Slim Tube experiment.The results show that both CO₂ and associated gas can be miscible with crude oil under reservoir conditions.Based on the static parameters such as reservoir structure characteristics and pore-permeability characteristics,and the history matching of reservoir production performance,a numerical model that can represent the actual characteristics of reservoir is established.The production profile of WX Reservoir in different scenarios was predicted by the numerical model established.And the selection of injection medium and the optimization of injection and production parameters were carried out by considering both the gas injection and production cost and the actual situation of the reservoir.In the end,the pilot test scheme was designed to guide the oilfield production.The pilot test scheme utilizes CO₂ as the injection medium,with 1% N₂ as impurity.single well injection rate of 300 m³/d at reservoir condition,a single CO₂ plug?CO₂injection time interval is March of 2020 to March of 2028?after the water flooding should be conducted.It is expected that the recovery rate will reach 48.88% by 2039,which is8.20% higher than the continuous water injection scenario,and 1.28% higher compared to the continuous gas injection scenario.