规则多边形孔隙毛细管压力理论模型  

The Theoretical Model of Capillary Pressure in Regular Polygonal Pores

作　　者：肖易航 郑军[1] 刘鑫[1] 何勇明[1] 周传友 XIAO Yi-Hang;ZHENG Jun;LIU Xin;HE Yong-Ming;ZHOU Chuan-You(College of Energy in Chengdu University of Technology,Chengdu 610059,China)

机构地区：[1]成都理工大学能源学院,成都610059

出　　处：《工程热物理学报》2021年第10期2587-2596,共10页Journal of Engineering Thermophysics

基　　金：国家自然科学基金(No.5177403);油气藏地质及开发工程国家重点实验室开放基金(No.PLC20210313)。

摘　　要：真实油气储层中的孔隙形状极为复杂,Yang-Laplace方程无法模拟多边形孔隙的毛细管行为。为了研究润湿性及孔隙几何形状对规则多边形孔隙毛细管行为的影响,基于MS-P理论及多边形孔隙两相驱替法则,在均匀润湿状态下推导出等边三角形、正方形、五角星形孔隙的排驱与自吸毛细管压力理论模型,在相同条件下,对不同润湿性及形状因子孔隙的毛细管行为进行分析。结果表明:相同润湿性的排驱与自吸渗流特征在孔隙角隅处相同,而在中央存在明显差异;随着接触角的增加,油相排驱阻力与水相自吸动力减小,油相自吸动力与水相强制自吸阻力增大;在特定润湿状态下,非润湿相在突破压力下完全饱和孔隙;均匀水湿体系的Snap-off程度随着接触角的增加而减小,而均匀油湿体系相反;形状因子对油相排驱过程的突破压力无明显影响;随着形状因子的增加,水相与油相自吸动力、水相强制自吸阻力减小,且非润湿相进入孔隙角隅时的非润湿相饱和度增大;五角星形孔隙的Snap-off现象最为明显。The pore shape in real oil/gas reservoir is very complex,and capillary behaviors of polygonal pores can not be simulated by the Yang-Laplace equation.In order to study effects of wettability and geometrical shape of pore in the capillary behavior of regular polygonal pores,based on the theory of MS-P and the rule of two-phase displacement in polygonal pore,theoretical models of drainage and imbibition capillary pressure for equilateral triangular,square and pentagonal pores are derived under the homogeneous wettability.And capillary behaviors of pores with different wettability and shape factors was analyzed under the same conditions.The results show:percolation characteristics of drainage and imbibition are same in pore corner under the same wettability,while the significant difference in pore center.With the increase of contact angle,oil drainage resistance and water imbibition driving force decrease,while oil imbibition driving force and water forced imbibition resistance increase.Non-wetting phase can completely saturate pore under the breakthrough pressure for the specific wettability.Snap-off level decreases with the increase of contact angle in the homogeneous water-wet system,while the law of homogeneous oil-wet system is opposite.Shape factor has no obvious influence on breakthrough pressure of oil drainage.With the increase of shape factor,oil and water imbibition driving force,water forced imbibition resistance decrease,and nonwetting phase saturation when non-wetting phase invades into pore corner increases.The Snap-off phenomenon is the most obvious in the pentagonal pore.

关 键 词：多边形毛细管 毛细管压力 Snap-off MS-P 润湿性 形状因子 

分 类 号：TE311[石油与天然气工程—油气田开发工程] O485[理学—固体物理]