A New Screening Evaluation Method for Carbon Dioxide Miscible Flooding Candidate Reservoirs

Prior to the implementation of CO۲ injection EOR projects, the screening evaluation of candidate reservoirs will promote the economic benefits of CO۲ injection. Currently, a uniform screening method for CO۲ miscible flooding does not exist. Based on more than ۱۱۲ successfully implemented CO۲ miscible flooding reservoirs, which was referred in ۲۰۱۰ Worldwide EOR Survey, and CO۲ miscible flooding mechanisms, this paper picks out ۱۲ reservoir and fluid parameters affecting CO۲ miscible flooding results as comprehensive evaluation parameters for screening candidate reservoirs. According to investigations on a large number of domestic and international CO۲ miscible flooding projects, the quantitative methods are determined by theoretical analyses, field experience, and probability statistics. By means of calculating the combinational weights by improved analytical hierarchy process (AHP) and entropy method and combining the advantages of technique for order preference by similarity to ideal solution (TOPSIS) with gray relational analysis to construct a new similarity nearness degree, the weighted GC-TOPSIS model is established for screening candidate reservoirs. This screening method was employed for the assessment of five classical candidate reservoirs proposed for CO۲ miscible flooding. The results show that this new method can correctly evaluate and compare the potential of CO۲ miscible flooding.

Keywords:

CO۲ Miscible Flooding , Screening Index , Evaluation Criteria , Ideal Solution , Grey Correlation