The Evaluation Method Of Carbon Dioxide Flooding Reservoirs Adaptability

Recently,the carbon dioxide displacement is one of the most important methods to enhance oil recovery for the advantages of decreasing interfacial intense and crude oil viscosity,expanding oil volume,improving oil and water mobility ratio and mixing with oil.Although CO₂ geological sequestration improves the green house effect and enhances oil recovery,not all reservoirs are suitable for CO₂ flooding,the effect is restricted by reservoir conditions.If the reservoir do not have the condition of CO₂ flooding,the oil recovery and economic benefit will not be enhanced.Therefore,it is necessary to evaluate the adaptability of CO₂ flooding reservoirs before exploitation.Applying the cluster analysis to evaluate carbon dioxide displacement adaptability of reservoirs.Through comparing with foreign successful reservoirs to evaluate the CO₂ injection adaptability of our country reservoirs.Using grey correlation to screen indices before analysis.Through calculating the correlation degree between indices and oil recovery,and the relationship among indices to establish the optimal reservoir index evaluation model.Then use the relevant principles of fuzzy mathematics to evaluate the adaptability of CO₂ flooding comprehensively.The main achievements are as follows:（1）On the basis of previous research,the carbon dioxide geological sequestration screen criteria and CO₂ flooding reservoirs characteristics and crude oil features can be obtained.（2）Put forward a new way of screening reservoir indices.Through calculating grey relational degree to obtain the association degree between indices and oil recovery and the order of importance.Then screen the indices by combing the relation degree with relationship among indices.Finally,the evaluation indices of CO₂ flooding reservoir will be get.（3）Using cluster analysis to evaluate the CO₂ flooding adaptability in Daqing Oilfield and Jiangsu oilfield comprehensively.The results demonstrated that Daqing oil field and Jiangsu Block 14 reservoir are suitable for CO₂ flooding,and both of them will get the better oil displacement effect.（4）Verify the cluster analysis result by using fuzzy analytical hierarchy process.Studies have shown that using cluster analysis method to evaluate the reservoir adaptability of injecting carbon dioxide is feasible.