再谈岩石本体变形的孔隙度不变原则  

Re-discussion on principle of constant porosity during primary deformation of rock

作　　者：朱苏阳[1] 李冬梅[2] 李传亮[1] 李会会[2] 刘雄志[3] ZHU Suyang;LI Dongmei;LI Chuanliang;LI Huihui;LIU Xiongzhi(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu 610599,China;Completion andWell Test Management Center,Sinopec Northwest Oilfield Company,Luntai 841600,Xinjiang,China;PetroChina Research Institute of Petroleum Exploration&Development-Northwest,Lanzhou 730020,China)

机构地区：[1]油气藏地质及开发工程国家重点实验室西南石油大学,成都610599 [2]中国石化西北油田分公司完井测试管理中心,新疆轮台841600 [3]中国石油勘探开发研究院西北分院,兰州730020

出　　处：《岩性油气藏》2021年第2期180-188,共9页Lithologic Reservoirs

基　　金：“十三五”国家科技重大专项“超高压有水气藏产能评价及气水流动模拟”(编号:2016ZX05066004-001)资助。

摘　　要：油藏岩石的本体变形中,骨架颗粒形状不变的假设认为岩石在压缩过程中孔隙度保持不变,然而,岩石骨架颗粒的形状并非严格保持不变。为研究骨架颗粒形状变化对孔隙度的影响,基于弹性变形模型,采用有限元数值模拟方法,研究了多孔介质本体变形过程中的骨架颗粒变形及其对孔隙度的影响机制。结果表明,加载过程中骨架颗粒在约束方向(颗粒接触位置)位移较小,在无约束方向(孔隙位置)位移较大,从而改变了颗粒的形状,降低了岩石的孔隙度,然而,岩石矿物的杨氏模量较大,且岩石中骨架颗粒的约束条件比数值实验中更为苛刻。因此,骨架颗粒变形对于孔隙度的影响极为微弱。数值实验中的刚性表皮仅对孔隙度的初始值有一定的影响;但是岩心夹持器中的柔性表皮则对测量过程有较大的影响,这是导致实验中孔隙度较大变化的直接原因。因此,油藏开采过程中,岩石的变形过程依然可以认为遵循“孔隙度不变性原则”。In the primary deformation of reservoir rocks,the assumption that the shape of the skeleton particles remains unchanged assumes that the porosity of the rocks remains unchanged during the compression process.However,the shape of the skeleton particles does not strictly remain unchanged.In order to study the influence of the shape change of skeleton particles on porosity,based on the elastic deformation model,finite element numerical simulation method was used to study the deformation of skeleton particles and its influence mechanism on porosity during the primary deformation of porous media.The results show that the displacement of skeleton particles is small in the constraint direction(particle contact position),and it is larger in the unconstrained direction(pore position),which changes the shape of the particles,reduces the porosity of rock.However,the young's modulus of rock minerals is larger,and the constraint conditions of the rock skeleton particles are more demanding than those in numerical experiments.Therefore,the effect of skeleton particle deformation on porosity is very weak.In the numerical experiments,rigid epidermis has only a certain effect on the initial porosity value.However,the flexible skin in the core gripper has a great influence on the measurement process,which is the direct cause of the great change of porosity in the experiment.Therefore,in the process of reservoir production,the deformation process of rock can still be considered to follow the“porosity invariance principle”.

关 键 词：岩石骨架 孔隙度 本体变形 有约束变形 数值模拟 表皮效应 

分 类 号：TE349[石油与天然气工程—油气田开发工程]