摘要
在低渗透介质中存在低速非Darcy渗流现象,启动压力梯度能够简明扼要地表述低速非Darcy渗流,有启动压力梯度的渗流运动方程是经典Darcy定律的补充和发展,是低渗透储层有效开发的理论基础。分析表明,在经典渗流理论范畴内,启动压力梯度决定于流体的性质、介质的表面作用和孔隙结构,渗流方式的改变不能影响启动压力梯度的性质;采用启动流量的方法,不能科学地表述低速非Darcy渗流现象。启动压力梯度的存在加剧了压力降落程度,使得"压降漏斗"变小、变尖;在启动压力梯度存在的情形下,压力分布曲线与原始地层压力的水平线相交,其交角随着启动压力梯度的增大而增加,存在压力扰动外边缘。
A threshold pressure gradient （TPG） associated with low permeability reservoirs can be used to describe non-Darcy flows at low velocity. A porous flow kinematic equation containing TPGs is an efficient supplement and development of the classical Darcy＇s law, which lays a solid theory foundation for the exploitation of low-permeability reservoirs. The study shows that in the classical porous flow theory, the essence of TPGs, which depends on properties of fluids, surface interaction and pore structures of media, is not affected by the variety of porous flow patterns. Therefore, non-Darcy flows at low velocity can not be scientifically described by the threshold flow rate derived from previous studies. The existence of TPGs can intensify degrees of the pressure decline, resulting in ＂the pressure cone of depression＂ smaller and sharper. However, the pressure distribution curve intersects with, instead of being tangent to, the initial reservoir pressure line when the TPG is greater than zero, and cut angles will become larger with the increase of TPGs, indicating the existence of outer boundaries of pressure disturbance.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2013年第1期188-191,共4页
Acta Petrolei Sinica
基金
国家重大科技专项(2011ZX05013-002
2011ZX05016-006)资助
关键词
启动压力梯度
低速非Darcy渗流
压力分布
低渗透介质
动外边界
threshold pressure gradient （TPG）
non-Darcy flow at low velocity
pressure distribution
low-permeability medium
moving outer boundary
