考虑弹塑性变形机制的储层天然裂缝闭合模型  

CLOSED MODEL OF THE RESERVOIR NATURAL FRATURE CONSIDERING THE ELASTIC-PLASTIC DEFORMING MECHANISM

作　　者：王一帆[1] 黄东安 闫博[1] 宋劼 刘炜超 王卫阳[3] WANG Yifan1 HUANG Dong＇an2 YAN Bo1 SONG Jie2 LIU Weichao1 WANG Weiyang3

机构地区：[1]中国石油大学石油工程教育部重点实验室,北京102249 [2]中国石油长庆油田分公司第十一采油厂,甘肃庆阳745000 [3]中国石油塔里木油田分公司,新疆库尔勒841000

出　　处：《大庆石油地质与开发》2017年第1期75-80,共6页Petroleum Geology & Oilfield Development in Daqing

基　　金：国家自然科学基金项目"多尺度离散裂缝油藏有限元数值模拟研究"(51204204)

摘　　要：针对裂缝闭合模型中存在的不足,提出一种新的弹塑性裂缝闭合模型。该模型基于经典接触力学理论,作出微凸体由弹性压缩首先转化为弹塑性压缩,最终转化为塑性压缩的过程是连续且光滑的假设。引入样板函数,对微凸体的完全弹性和完全塑性的压缩状态进行衔接,并推导出微凸体压缩过程中的状态方程。在此基础上,采用微凸体概率分布理论,导出裂缝复合表面与光滑平面之间的接触面积、平均接触压力、法向应力和裂缝闭合量之间的函数关系式。将建立的模型同完全弹性和完全塑性模型进行对比,结果表明新模型能够良好地描述裂缝闭合时上下两表面接触面积和平均接触压力的变化规律,同时对于法向应力对裂缝闭合的影响更加符合直觉和实验观察,能够合理地描述裂缝的闭合规律。In view of the shortcomings of the crack closure model,a new type of elastic-plastic fracture closed model was proposed. The model is based on the theory of the classical contact mechanics and made by the microconvex body by means of the transformations first from the elastic compression into the elastic-plastic one and finally into plastic one with the help of the assumption of the continuous and smooth compression processes. By introducing the model function,the states of the fully elastic and fully plastic compressions of the micro-convex body are connected,and the state equation of the micro-convex body is introduced for the processes stated above. On the basis of these achievements,by using the theory of the probability distribution of the micro convex body,the function relational expressions are derived among the contact area,average contact pressure,normal stress and crack closure between the composite surface and the smooth plane. The contrasts between the setup model and perfectly elastic and fully plastic models show that new model can well describe the changed laws of the contact area and averagecontact pressure for the two top-bottom surfaces during the crack closure,and moreover the influences of the normal stress on the crack closure are more intuitively and experimentally observed,so the crack closure rules can be more reasonably characterized.

关 键 词：天然裂缝 弹塑性 闭合模型 微凸体 

分 类 号：TE344[石油与天然气工程—油气田开发工程]