泥岩浸水对应力应变扰动的数值模拟  

Numerical simulation study on disturbance of stress and strain induced by mudstone soaking during development of oilfield

作　　者：易金[1,2] 李自安[1] 张露[3] 朱江建[1,2] 朱炎 陈广浩[1] 林舸[1] 

机构地区：[1]中国科学院广州地球化学研究所,广东广州510640 [2]中国科学院研究生院,北京100049 [3]中国科学院对地观测与数字地球中心,北京100101 [4]中国石油股份大庆油田分公司采油五厂,黑龙江大庆163453

出　　处：《油气地质与采收率》2012年第6期95-99,103,共6页Petroleum Geology and Recovery Efficiency

基　　金：国家重点基础研究发展计划"973"项目"南海深水区盆地形成机理与演化过程研究"(2009CB219401)

摘　　要：以大庆油区杏树岗南部开发区为例,对注采过程中泥岩浸水软化引起的应力应变局部扰动进行了数值模拟研究,探讨了泥岩浸水对应力应变的扰动,以及对地层压力与应力应变关系的影响。结果表明,泥岩浸水对不同层位应力的扰动情况各不相同,造成了层间应力状态的差异。层间应力状态的差异、泥岩层浸水后自身力学性质的弱化、注采引起的层内及层间孔隙流体压差、泥岩层与砂岩层之间渗透率和岩性的差异以及高压注水引起的有效应力降低等因素综合作用,导致萨尔图油层组的萨Ⅰ—萨Ⅱ泥岩夹层附近剪切应变高度集中,进而引起泥岩夹层套管的剪切变形与错断。萨Ⅰ—萨Ⅱ泥岩夹层的剪切应变增量随泥岩含水率的增大而增大,且其随地层压力增大而增大的速率在泥岩浸水后明显增大。因此,在泥岩浸水后,应适当降低泥岩夹层毗邻储层的注水压力和地层压力,从而缓解泥岩夹层的剪切套损。This paper introduced a numerical simulation study on disturbance of stress/strain induced by mudstone soaking during injection and production activities in the Xingshugang area of the Daqing Anticline,Songliao Basin,China.The variations of stress and strain in different water contents of mudstone layers are researched in this paper.The relationships between formation pressure and stress and strain pre and post mudstone soaking are also investigated,so as to offer an evidence for a reasonable design of injection and production technique.Results indicate that different horizons have different stress responses to the soaking of mudstone.Besides,the different stress responses of different horizons,weakening of mechanical property of rocks due to the mudstone soaking,difference of pore pressure in a layer or between layers,difference of property and permeability between mudstone and sandstone,and reducing of effective stress as a result of high pressure injection giving rise to the concentration of shear strain along S Ⅰ-S Ⅱ mudstone layer.And,then it results in shearing casing damage of mudstone layers.Shear strain is rising with the increase of water contents of mudstone layers,and its shear strain rising rate is proportional to the increase of water contents.So,reducing the water injection pressure and formation pressure of reservoirs close to mudstone layers is needed to relieve shearing casing damage after mudstone soaking.

关 键 词：泥岩浸水 应力应变套管损坏 储层注水 数值模拟 大庆油区 

分 类 号：TE34[石油与天然气工程—油气田开发工程]