含水低渗透多孔介质气体低速非达西理论研究  

Theoretical study on low velocity non-Darcy gas flow in low-permeability water-bearing porous medium

作　　者：邱忠贤[1] 刘月田[1] 涂彬[1] 

机构地区：[1]中国石油大学,北京102249

出　　处：《特种油气藏》2009年第1期79-81,105,共4页Special Oil & Gas Reservoirs

摘　　要：从分析气体驱替过程气水界面上气水毛管力构成入手,通过假设液固界面作用产生的流体边界层的极限剪切应力的递减规律,建立完全饱和水的毛细管气体驱替模型,并得到气水两相时气体临界流动压力的相关理论计算公式;由非混相渗流模型进一步得出气体最低渗流阻力与含水饱和度相关的结论。研究表明,低渗透岩心高含水情况下,气体临界流动压力主要由边界层的极限剪应力与气水毛管力构成,其中毛管力是主要的驱替阻力,边界层的影响在渗透率较低的情况下才表现出来。临界流动压力反映了毛细管力与边界层作用对气体渗流的影响,并使气体表现出非达西渗流特征。由于毛细管力将会随含水饱和度发生变化,因此可动水饱和度的变化会引起渗流阻力发生改变,而渗流阻力的变化也是气体产生非达西渗流的原因。This paper analyzes the constitution of capillary pressure on gas-water interface during gas displacement process, assumes the decline pattern of the limiting shear stress at fluid boundary due to liquid-solid interface action, establishes a capillary gas displacement model of saturated water, and derives a theoretical calculation formula of critical gas flow pressure in two-phase of gas and water. It is further concluded through immiscible percolation model that the minimum filtrational resistance of gas is related to water saturation. Study shows that in low permeability core with high water cut, the critical gas flow pressure is composed of limiting shear stress and capillary pressure at boundary, of which the capillary pressure is the major displacement resistance and the effect of boundary only occur when permeability is low. Critical flow pressure reflects the impact of capillary pressure and boundary effect on gas percolation, and causes non-Darcy gas flow. Because capillary pressure changes with water saturation, the change of mobile water saturation will cause the change of filtrational resistance, which is another cause of non-Darcy gas flow.

关 键 词：低渗透气藏 气水两相 毛管力 低速非达西渗流 

分 类 号：TE312[石油与天然气工程—油气田开发工程]