Evaluation method for CO2 flooding suitability of condensate gas reservoir based on fuzzy analytic hierarchy process

Abstract

CO2 injection to the middle and late stage of development of condensate gas reservoir can not only improve gas well recovery, but also realize the stable storage of CO2, which is of great practical significance to our energy development strategy, and conducive to the realization of "peak carbon neutralization". Comprehensive evaluation of CO2 injection suitability before CO2 injection in condensate gas reservoirs is an important basis for successful CO2 flooding in the field. Firstly, a comprehensive evaluation method of CO2 flooding suitability for condensate gas reservoirs is established based on fuzzy mathematics; secondly, on the basis of literature research, existing indoor experiments and field experience, the influencing factors of CO2 injection in condensate gas reservoirs are summarized, and new evaluation criteria of CO2 injection suitability (4 primary indicators and 14 secondary indicators) are established and quantified; finally, the weights of 4 primary indexes and 14 secondary indexes are determined by AHP(analytic hierarchy process). Based on the above evaluation method, three blocks of HC gas reservoir were evaluated for the suitability of CO2 injection, and the practicality and reliability of this evaluation method were verified by comparing the evaluation results with the ultimate recovery of condensate gas reservoir in each block. This provides a new idea for the scheme adjustment of further development in the middle and later stages of condensate gas reservoir development.