煤层水力压裂网状裂缝形成条件分析  

Condition analysis of forming map cracking in coal seam hydraulic fracturing

作　　者：李玉伟[1] 艾池[1] 于千[2] 张博文[1] 金丽娜[3] 

机构地区：[1]教育部提高油气采收率重点实验室东北石油大学,黑龙江大庆163318 [2]中油大庆油田有限责任公司,黑龙江大庆163414 [3]中国地质大学,北京100083

出　　处：《特种油气藏》2013年第4期99-101,155-156,共3页Special Oil & Gas Reservoirs

基　　金：国家自然科学基金"基于混沌理论煤层气井压裂孔裂隙分形演化与渗流特征研究"(51274067)

摘　　要：为确定煤层水力压裂形成网状裂缝力学条件,应用弹性力学理论,将煤岩体的面割理和端割理简化为贯通和断续裂缝,基于裂缝张性断裂和剪切破坏准则,建立了缝内临界净压力计算模型。应用模型计算表明:缝内临界净压力随贯通裂缝倾角增加呈周期性变化,倾角从0～90°为1个变化周期,当倾角为0、90°时,缝内临界净压力值最大为水平最大主应力与最小主应力差值;裂缝壁面内摩擦系数对缝内临界净压力最大值基本无影响,而缝内临界净压力最小值随裂缝壁面内摩擦系数的增加而增大。In order to determine the mechanical conditions of forming map cracking in coal seam hydraulic fracturing,we applied the elastic mechanics to simplify the butt cleat and face cleat of coal seam into penetrating and intermittent fractures,and established a calculation model of critical net pressure inside cracks when map cracking system is formed by opening of both penetrating fractures and intermittent fractures in coal seam fracturing based on the principle of tensional fracture and shear fracture.The calculation model indicates that the critical net pressure shows cyclic variation along with the change of penetrating fracture dip,which presents a cycle from 0° ～ 90 °;when the dip is 0° and 90 °,the maximum critical net pressure inside cracks equals to the difference between maximum and minimum horizontal principle stresses;the friction coefficient of fracture wall has basically no impact on the maximum critical net pressure,while the minimum critical net pressure increases with the increase of friction coefficient of fracture wall.

关 键 词：煤岩体 水力压裂 网状裂缝 计算模型 张性断裂 剪切滑移 净压力 

分 类 号：TE357.1[石油与天然气工程—油气田开发工程]