致密砂岩油藏微纳米孔喉动态渗吸毛管力效应控制机理

Water huff and puff is a vital development method for tight sandstone oil reservoirs. One general mechanism for water huff and puff is that the capillary pressure drives oil in the micro-nano pores out of the matrix through dynamic imbibition, where the capillary pressure is significantly affected by the dynamic effect. Thus, the control of the dynamic effect in capillary pressure can lead the capillary pressure to facilitate the dynamic imbibition and improve the water huff and puff performance. This project aims to conduct water huff and puff lab experiments on tight sandstone cores by improving and applying the self-developed apparatus and methods for evaluation of the dynamic effect in capillary pressure, thus demonstrating the capillary pressure and its dynamic effect. Moreover, the effect of wettability, interfacial tension, oil viscosities and boundary conditions, which are the factors to determine the water huff and puff performance, will be investigated. The mathematic model of the dynamic effect in capillary pressure in tight sandstone during the dynamic imbibition process will be established through the application of the comprehensive analogy method, the dimension analysis method, and the multiple regression method. This mathematic model will clarify the main controlling factors of the dynamic effect. Therefore, the control mechanism of the dynamic effect in capillary pressure will be revealed and its control method will be formed. This project will improve the theory of multi-phase flow in tight sandstones, which will provide guidance for the optimum design of the water huff and puff program on tight sandstone oil reservoirs.

注水吞吐是致密砂岩油藏的重要开发方式，其主要采油机理之一为毛管力等作用下基质微纳米孔喉内赋存原油被动态渗吸置换出来，其中毛管力受动态效应影响较大，因此对毛管力动态效应进行调控，有助于充分发挥毛管力的作用，促进动态渗吸，提升致密砂岩油藏注水吞吐采油效果。本项目拟通过改进自主研发的毛管力动态效应评价系统和方法，实验模拟致密砂岩注水吞吐过程，明确致密砂岩微纳米孔喉动态渗吸时的毛管力行为和动态效应特征；实验研究毛管力动态效应对润湿性、油水界面张力、边界条件和流体粘度等注水吞吐影响因素变化的响应机制；在此基础上，基于综合类比法、量纲分析法和多元回归分析法建立致密砂岩微纳米孔喉动态渗吸毛管力效应数学模型，明确毛管力动态效应主控因素，揭示其控制机理，并形成相应的控制方法。研究成果将丰富致密砂岩油藏多相渗流理论，可为致密砂岩油藏注水吞吐开发方案优化设计提供指导。

注水吞吐是致密砂岩油藏的重要开发方式，其主要采油机理之一为毛管力等作用下基质微纳米孔喉内赋存原油被动态渗吸置换出来，其中毛管力受动态效应影响较大。本项目改进了自主研发的毛管力动态效应评价系统和方法，实验模拟了致密砂岩注水吞吐过程，明确了致密砂岩微纳米孔喉动态渗吸毛管力行为和动态效应特征；实验研究了毛管力动态效应对润湿性、油水界面张力、边界条件和流体粘度等注水吞吐影响因素变化的响应机制；基于综合类比法、量纲分析法和多元回归分析法建立了致密砂岩微纳米孔喉动态渗吸毛管力效应数学模型，明确了毛管力动态效应主控因素，揭示了其控制机理，并形成相应的控制方法。对毛管力动态效应进行调控，有助于充分发挥毛管力的作用，进动态渗吸，提升致密砂岩油藏注水吞吐采油效果。研究成果将丰富致密砂岩油藏多相渗流理论，可为致密砂岩油藏注水吞吐开发方案优化设计提供指导。