摘要
注气重力驱是碳酸盐岩油藏一种有效的开发方式,但碳酸盐岩油藏裂缝广泛发育,注气过程中油-气-水多相流动规律复杂,力学机制不清,分析裂缝中油-气-水多相流动力学机制尤为重要。首先,考虑注气压差、重力、黏滞阻力和毛管力等各种作用力,构建裂缝油-气-水多相流动力学模型,得到裂缝中流体所受剪切应力与平均流速的关系;其次,推导油-气-水界面运移时间的解析表达式;最后,定量研究裂缝宽度、注气压差、润湿性、毛管力等因素对多相流动的影响,分析裂缝中各作用力的相互制约关系,提出一种可忽略毛管力时的临界裂缝宽度定量判别方法。研究结果表明:裂缝多相流动速度与裂缝宽度呈二次方关系,裂缝越宽,流动速度越大;随着裂缝宽度增大,润湿性对流动速度的影响逐渐变小;当油-气毛管力和油-水毛管力合力与流动方向一致时,毛管力合力越大,流动速度越快;当毛管力合力小于10^(-10)N,毛管力对流动速度的影响可以忽略不计。所构建的裂缝宽度-受力双对数图版可以有效判定可忽略毛管力时的临界裂缝宽度。
Gas gravity drainage is an effective development method for carbonate oil reservoirs,but fractures are widely developed in carbonate reservoirs.The law of multiphase flow of oil,gas and water during gas injection is very complicated and the mechanism is unclear.It is particularly important to analyze the dynamic mechanism of oil-gas-water multiphase flow in fractures.Firstly,the mechanism of oil,gas and water multiphase flow in a fracture was analyzed,and various forces such as injection pressure difference,gravity,viscous resistance and capillary force were considered.The relationship between shear stress and average velocity of fluid in a fracture was obtained.Secondly,the analytical expressions of displacement time of oil,gas and water interface was deduced,and the effects of fracture width,injection pressure difference,wettability and capillary force on multiphase flow were quantitatively studied.The interaction between each force in a fracture was analyzed.A method of quantitatively determining the critical fracture width where the capillary force can be ignored was proposed.The results show that the multiphase flow velocity and fracture width have a quadratic relationship.The wider the fracture,the greater the flow velocity.With the increase of fracture width,the influence of wettability on the flow velocity becomes smaller.When the resultant force of oil and gas capillary force and oil-water capillary force are consistent with the flow direction,the greater the resultant force of capillary force is,the faster the flow velocity is.When the resultant force of capillary force is less than 10^(-10) N,the influence of capillary force on the flow velocity can be ignored.The double logarithm chart of fracture width versus force can be used to quantitatively determine the critical fracture width where the capillary force can be ignored.
作者
王付勇
赵久玉
WANG Fuyong;ZHAO Jiuyu(State Key Laboratory of Petroleum Resources and Prospecting,Beijing 102249,China;Unconventional Petroleum Research Institute,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China)
出处
《中南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2021年第11期3990-3998,共9页
Journal of Central South University:Science and Technology
基金
国家自然科学基金资助项目(51874320)。
关键词
碳酸盐岩油藏
裂缝
注气
多相流动
力学机制
渗流规律
carbonate reservoir
fracture
gas injection
multiphase flow
capillary pressure
seepage law
