Adaptability Research Of CO₂ Foam Flooding In The Typical Block Of Daqing Yushulin Oilfield

In this paper,the typical block chosen in Yushulin oilfield is Block A,which belongs to the high temperature and high pressure of ultra-low permeability reservoir.There exists the issue that continuous CO₂ flooding will lead to the problem of invalid production under the high pressure situation.Aiming at the situation,this paper proposed the measure of foam flooding.Foam can effectively block the macroscopic throats,which can control the gas channeling due to CO₂ flooding;surfactant in the foam has the property of reducing the interfacial tension of crude oil,which can improve the efficiency of washing oil;foam can decrease the mobility of gas,compel gas to the displacement range,enlarge sweep volume and produce low permeability layer effectively.Because the research in this paper was conducted on the basis of CO₂ flooding,CO₂-foam flooding was selected as the gas foam flooding measure.Aiming at the characteristics of Block A in Yushulin oilfield,indoor physical experiments of the optimization of foaming agent,stable foam agent and stable adhesion agent had been carried on firstly.The performance evaluation experiment of the optimum foam system also had been done.This paper also measured the viscosity-concentration relationship,the absorptive capacity,the rheological property and the relative permeability of the optimum foam system.The optimum CO₂-foam system were as follows:?1?CO₂+0.4% FP04 + 0.1% WP125+150mg/L LN;?2?CO₂+0.4% DY-1 + 0.1% WP125+150mg/L LN.Based on the seismic data and the drilling data provided by Daqing Yushulin oilfield,the paper calculated the permeability,the oil saturation and the porosity by phased interpolation etc.and set up the geological model of the purpose block by Petrel software.Based on the geological model,the reservoir strata parameters,the high pressure physical properties data of fluids and the relative permeability curve,the numerical simulation of CMG-GEM model was established for CO₂ flooding.By combining the actual production data provided by oil field,the history fitting of single well and the whole district was done.The paper also analyzed the effective measures to enhance oil recovery based on the remaining oil distribution of reservoir.At the same time,the paper used the CMG-STARS software to do the numerical simulation research which was suitable for foam flooding.The basic prediction was gone on the basis of the original CO₂ flooding,then the ratio of gas and liquid and slugcombination of foam were optimized.The development index prediction results indicated that:the slug injection was the suitable injection pattern of the Block A in Yushulin oilfield,the best injection slug combination was [foam flooding?8.5 months?+ gas flooding?8.5 months?]×4,and the ratio of gas and liquid was 1:1.Through the adaptability analysis,CO₂-foam flooding had a certain ability to enhance oil recovery for purpose block.