摘要
有效应力是多孔介质力学的基础概念,固体力学的理论通过有效应力应用于多孔介质,产生了多孔介质力学。但是,不同学者在不同条件下提出的有效应力有所不同,这就给有效应力的应用带来了不确定性。目前已提出了3个典型的有效应力:Terzaghi有效应力、Biot有效应力和双重有效应力。Terzaghi有效应力是针对疏松土介质提出的第一个有效应力,催生了土力学的诞生,它仅适用于极其疏松的多孔介质,不适用于致密介质的力学行为研究。Biot有效应力是对Terzaghi有效应力的修正,由于Biot系数没有明确的物理意义,又通常取经验值,因此Biot有效应力公式是一个经验公式。双重有效应力是在介质变形机制基础上提出的有效应力概念。多孔介质存在两种基本的变形机制:本体变形和结构变形。与此相对应,多孔介质存在两个有效应力:本体有效应力和结构有效应力。本体有效应力决定多孔介质的本体变形,结构有效应力决定多孔介质的结构变形。双重有效应力考虑了多孔介质的物质结构,引入了多孔介质的物性参数,参数取不同的数值,可用于不同的介质类型。毛博士提出的新双重有效应力概念定义不严谨,科学性不强,无法通过实践检验。多孔介质的孔隙压缩系数与孔隙度不是负相关,而是正相关。
Effective stress is a fundamental concept of the mechanics of porous media, through which the theory of solid mechanics is applied to porous media. However, the effective stresses proposed by different researchers are quite different, which brings about uncertainty to the application of effective stress. Three typical effective stress approximations have been proposed so far. These are Terzaghi’s effective stress, Biot’s effective stress and dual effective stresses. Terzaghi’s effective stress was the first concept of effective stress proposed for soil, which brought about the birth of soil mechanics. Terzaghi’s effective stress is only applicable to extremely loose material and is not applicable to the study of the mechanical performance of tight media. Biot’s effective stress is a modification to Terzaghi’s effective stress. Because Biot’s coefficient has no clear physical meaning and usually takes empirical values, Biot’s effective stress equation is only an empirical equation. Dual effective stresses are proposed based on the deformation mechanism of porous media. There are two basic types of deformation for porous media: primary deformation and structural deformation, and correspondingly, there are two effective stresses for porous media. These are the primary effective stress and the structural effective stress. The primary effective stress determines the primary deformation of porous media, and the structural effective stress determines the structural deformation of porous media. Dual effective stresses take in account the physical properties of porous media and take the physical parameters of porous media into the formula, which can be applicable to different media as the physical parameters take different values. The concepts of new dual effective stresses proposed by Dr Mao are loosely defined and are scientifically weak, and they cannot pass practical tests. For example, the pore compressibility of porous media is not negatively but positively correlated with porosity.
作者
李传亮
朱苏阳
LI Chuanliang;ZHU Suyang(Petroleum Engineering School,Southwest Petroleum University,Chengdu 610599,China)
出处
《石油科学通报》
2019年第4期414-429,共16页
Petroleum Science Bulletin
基金
国家重大专项“大庆长垣特高含水油田提高采收率示范工程”(2016ZX05054)资助
