Effect Evaluation And Reservoir Adaptability Of Chemical Flooding For High Temperature And High Salinity Reservoir

Chemical flooding is one of the most effective enhanced oil recovery technologies currently in China, and polymer flooding and polymer-surfactant flooding are two different chemical flooding techniques for high temperature and high salinity reservoirs. With the continuous development of the two kinds of chemical flooding methods and the gradual appearance of flooding effects, analyzing the dynamic characteristics and the regularity of flooding, establishing chemical flooding effect evaluation indexes system and evaluation methods, determining selection criteria of reservoir conditions of the different chemical flooding systems, discussing their reservoir adaptability, provide a theoretical foundation for application and popularization of chemical flooding technologies to enhance oil recovery in high temperature and high salinity reservoir.In this paper a series of new chemical flooding evaluation indicators and evaluation methods were set up. Based on reservoir engineering analysis methods and numerical simulation techniques, a more systematic evaluation indexes and evaluation methods to evaluate the chemical flooding development efficiency of single-well and the situation of heterogeneity between wells was established. Based on reservoir heterogeneity and the water cut of production wells, a simple and practical method of production and injection rate proration was established. According to the numerical simulation results and type C water drive characteristic curve, an evaluation method to evaluate the contribution of chemical flooding mechanism was established, by which the contribution of expanding sweep efficiency mechanism and increasing oil displacement efficiency mechanism of the chemical agents could be obtained. An oil increment evaluation index considering the time value of money was established. The recovery of water flooding and subsequent water flooding following chemical flooding could be predicted by the improved new oil recovery and water cut quantitative prediction model.Filter indicators system and selection criteria of polymer flooding and polymer-surfactant flooding consider the oil price volatility was established for the first time. Based on chemical investment and cost composition analysis and dynamic economic evaluation methods, formulas of chemical flooding incremental net present value, economic limit of oil increment and economic limit of enhanced oil recovery were deduced, thereby a research method of chemical flooding reservoir conditions screening criteria was established, through which the screening criteria of polymer flooding and polymer-surfactant flooding were set up under different prices, it's useful to facilitate chemical flooding reservoir filter according to oil price fluctuations dynamically.A comprehensive evaluation method of chemical flooding reservoir adaptability was established on the basis of fuzzy analytic hierarchy process method. Research shows that: polymer flooding have higher fitness in low oil prices, with the rise in oil prices, there is a critical values of oil price at which the fitness level of polymer-surfactant flooding is higher than polymer flooding. This method could be used to choose best reservoir for chemical flooding and best chemical flooding methods, and avoid the evaluation defects of "one-vote-down" method, it's beneficial to guide high temperature and high salinity reservoir for selective and efficient chemical flooding development.