低渗透油藏渗流物理特征的几点新认识

New insights into the physical percolation features of low-permeability reservoirs

计秉玉 赵宇 宋考平 许关利

Ji Bingyu Zhao Yu Song Kaoping Xu Guanli

中国石化 石油勘探开发研究院, 北京 100083 2. 东北石油大学 石油工程学院, 黑龙江 大庆 163318

SINOPEC Petroleum Exploration & Production Research Institute, Beijing 100083, China 2. School of Petroleum Engineering, Northeast Petroleum University, Daqing, Heilongjiang 163318, China

对于低渗透油藏,油水界面张力、岩石润湿性和孔喉比是影响产量和采收率的重要因素,而润湿指数和润湿角通过毛管数与驱油效率有直接的定量关系。该文提出了一个关联着界面张力、润湿性和孔喉比的修正毛管数概念,建立了基于Amott润湿指数与USBM指数的润湿角表征方法,继而推导出低渗透储层毛管数表达式,并通过岩心实验确定出其与残余油饱和度的关系。以此为基础给出不同界面张力与润湿情况下的相对渗透率曲线、驱油效率和注入能力的计算公式,揭示了各种油藏物理参数之间的关联性,为优化低渗透油层化学驱改变界面张力、润湿性控制参数,进而为提高驱油效率和采收率提供了理论依据。

For low-permeability reservoirs, interfacial tension, rock wettability and pore-throat ratio are important factors affecting production and recovery. Wettability index and wetting angle have a direct quantitative relationship with oil displacement efficiency. This paper presents a concept of modified capillary number associated with interfacial tension, rock wettability and pore-throat ratio, and establishes a wetting angle characterization method of low-permeability reservoir based on Amott wettability index and USBM index. We also derive a capillary number expression for low-permeability reservoirs and determine the relationship with residual oil saturation through core test. Based on this, the calculation formulas of a relative permeability curve, oil displacement efficiency and injection ability are given for different conditions of interfacial tension and wetting angle, which reveals the relationship between reservoir physical characteristics. The study provides a theoretical basis for optimizing chemical flooding, changing interfacial tension and wettability controlling parameters in low-permeability reservoir, and further improves oil displacement efficiency and recovery.

中国博士后科学基金"低渗透油藏CO驱替特征及优化开采研究" (2010047050)、国家自然科学基金重点项目"低渗透油层提高驱油效率的机理研究"(50634020)和国家自然科学基金青年科学基金"微观孔隙内原油活化条件的动力学机理研究"(51104030)共同资助。

https://doi.org/10.11781/sysydz201502129