水力裂缝逼近时天然裂缝稳定性分析  

Stability of the Natural Fracture When the Hydraulic Fracture Is Approaching

作　　者：赵金洲[1] 杨海[1] 李勇明[1] 王刚 伍洲[1] 

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500 [2]新疆石油工程建设监理有限公司,新疆克拉玛依834009

出　　处：《天然气地球科学》2014年第3期402-408,共7页Natural Gas Geoscience

基　　金：中国石油科技创新基金(编号:2011D-5006-0201);新世纪优秀人才支持计划(编号:NCET-11-1062);四川省杰出青年学术技术带头人资助计划(编号:2012JQ0010)联合资助

摘　　要：在考虑天然裂缝闭合程度的情况下,基于弹性力学及断裂力学理论,建立了水力裂缝逼近天然裂缝时天然裂缝面应力场模型并得到其解析解,同时进一步明确了水力裂缝诱导应力的意义及其作用方式。天然裂缝稳定性影响因素敏感性分析表明:水力裂缝在逼近天然裂缝过程中会在很大程度上影响天然裂缝的稳定性,影响因素包括水平应力差异系数、水平主应力差值、逼近角、逼近距离、净压力、天然裂缝闭合程度以及水力裂缝长度,其中水平应力差异系数、水平应力差、逼近角以及净压力的影响最为显著,逼近角与逼近距离还会影响失稳中心点的位置。分析了各个因素对失稳区域范围的影响,明确了影响天然裂缝稳定性的因素以及影响程度,为建立准确、完善、系统的缝网压裂理论奠定基础。Considering the degree of natural fracture closure, a stress field model of natural fracture face with approaching hydraulic fracture is developed via elasticity theory and fracture mechanics. Moreover, this paper clarifies the definition of induced-stress of hydraulic fracture and the way it works. Based on the sensitivity study of influences on natural fracture stability, it is found that the approaching hydraulic frac- ture can significantly affect the stability, and the factors include the horizontal principal stress ratio, hori- zontal principal stress contrast, approaching angle, approaching distance, net pressure, degree of natural fracture closure and the length of hydraulic fracture. In this study, it is also found that the approaching an- gle and approaching distance deviate the position of shear failure center from original,and the＂ role of hori- zontal principal stress contrast and its ratio, approaching angle and the net pressure are much more critical in stability of natural fracture than other factors. This paper also analyzes the range within which the shear failure occurs. According to the analysis of the stability of natural facture when the hydraulic facture is approac- hing,the impacts of hydraulic fracture to the stability of natural fracture are expounded in this paper; therefore,it provides a foothold for developing an accurate and systematic theory of network fracturing in future.

关 键 词：天然裂缝稳定性 裂缝网络 缝网压裂 水力裂缝延伸 

分 类 号：TE357.1[石油与天然气工程—油气田开发工程]