Study on enhanced oil recovery of Ren 11 fractured bottom water reservoir by gas injection

The feasibility of enhanced oil recovery (EOR) of Ren 11 fractured bottom water reservoir by gas injection was studied. The geological characteristics of gas injection and production performance by water flooding were comprehensively studied and evaluated. Based on the tested results of oil displacement by nitrogen injection in Yanling Oilfield, the mechanism of oil displacement by gas injection and the movement rules of fluid interface were investigated. A plan for producing oil by gas injection was worked out. The relation between underground gas storage and EOR measures was coordinated. The results show that the cap rock of Ren 11 fractured bottom water reservoir has good sealing property, and secondary gas cap and oil enrichment zone can be formed there. The geologic condition of Ren 11 reservoir is suitable for gas injection to enhance oil recovery and for establishment of underground gas storage. It is suggested that oil recovery can be improved in fractured buried hill reservoirs by building underground gas storage while injecting gas.