_超低界面张力的二元驱油体系对水驱残余油启动和运移机理

1、Effect Mechanism of Polymer /Surfactant Combination Solution on Residual Oil The Background1. ASP combination solution flooding had been used in industrial field test in XXX Oilfield, the recovery was enhanced more than 12%.2. The problems of ASP flooding (1) The clay is dispersed and migrated; (2)

2、The alkali incrustation is formed; (3) The viscoelasticity of polymer solution is reduced.The main work 1. The influence of viscoelasticity of SP solution on recovery efficiency;2. The influence of interfacial tension of SP solution on recovery efficiency;3. The analysis of startup and migration mec

3、hanism of residual oil.1.Oil Displacement Experiments on Visual Glass Models 1.1 Oil Displacement Experiments In oil displacement experiments, glass etched model is used, the images of oil displacement process are translated into computer digital signal by the image collection system, the microscopi

4、c oil displacement process of SP solution is analyzed by the image analysis technology. 1.2Chemicals (1) Polyacrylamide (PAM) is manufactured by Daqing Reagent Factory and the average relative molecular mass is 500104 and 1600104 separately.(2) Surfactant is carboxyl betaine amphoteric surfactant de

5、veloped by ourselves. The structure of carboxyl betaine is as follows: Where R is alkyl or hydrocarbyl with long carbon chain. SP compound solutionSolution 1Solution 2Solution 3HPAMRelative molecule mass50010416001041600104Mass concentration(mg/L)100010001000Content of surfactant (%)0.0250.0250.200I

6、nterfacial tension (mN/m) 2.8910-25.4110-25.8210-31.3 Composition and characteristic of SP compound solutionTable 1. Composition and interfacial tension of SP compound solution2. The results and analysis of experiment 2.1 The influence of viscoelasticity (a) Water Solution 1 (b) Water Solution 2 Rel

7、ative molecule mass500104Relative molecule mass 1600104Recovery efficiency with different viscoelasticity79.04%84.19%26.15%24.36%2.2The influence of interfacial tension (b) WaterIFT=5.4110-2mN/m IFT=5.8210-3mN/m (c) Water Solution 3 Solution 2Recovery efficiency with different interfacial tension84.

8、19%26.15%95.52%39.72%3. Startup and migration mechanism of residual oil3.1 The startup of residual oilResidual oil is drawn into oil droplets(a)(b)(c)(d)Residual oil is stretched to oil thread (a) Residual oil (b) Elongation (c) Thread formed(d) Residual oil disappeared The oil thread is drawn into

9、droplets (a)(b)(c)(d)3.2 The migration of residual oil The oil-drop passes the pore throat The oil-drop is stretched into oil thread and oil thread is drawn into more small droplets .Oil-drop is drawn into small oil-drops when it passes the narrow channel.(1) The viscoelastic characteristic of polym

10、er and the ultra-low interfacial tension characteristic of the surfactant solution can be utilized fully in the SP solution flooding process. The effect of SP solution with ultra-low interfacial tension on residual oil after water flooding is better than that of the increase in viscoelasticity of solution. Summary(2) The main mode of startup is that residual oil is drawn into the oil- drop and oil thread, a great deal of oil-drop with different size is formed and migrated. Dur