地应力改变对水力裂缝扩展的模拟实验研究  

Experiment Research on Hydraulic Fracture Propagation under In-suit Sltered-stress

作　　者：卜向前[1] 周大伟[2] 李向平[1] 吕宝强[1] 张广清[2] 

机构地区：[1]长庆油田分公司油气工艺研究院,西安710021 [2]中国石油大学(北京)石油天然气工程学院,北京102249

出　　处：《科学技术与工程》2015年第35期24-28,共5页Science Technology and Engineering

基　　金：优秀青年科学基金项目(51322404)资助

摘　　要：采用RTM-1大尺寸岩石三轴力学性质测试装置测试人工试件(300×300×600 mm^3),模拟在改变水平地应力方向及大小的条件下,研究重复压裂裂缝的形成和扩展过程:已有裂缝的偏转和新裂缝的形成。实验结果表明:1重复压裂形成新裂缝的过程中,已有裂缝会重张、起裂偏转,已有裂缝的偏转主要以剪切破坏形式为主;2水平地应力发生改变时,不一定就产生新裂缝:-K'_h越小,已有裂缝越容易发生偏转;-K'_h越大,已有裂缝壁面上越容易产生单翼新裂缝,产生新裂缝临界条件是-K'h=5/7;3注入速率Q对新裂缝的产生影响较大:当Q较小时,已有裂缝壁面上不易产生新裂缝,仅发生已有裂缝的偏转;当Q较大时,已有裂缝壁面上容易产生单翼新裂缝。Using RTM-1 large size true-triaxial rock mechanics test device tests specimen（ 300 × 300 × 600mm^3）,and under the condition of changing horizontal in-suit stress direction and size,the initiation and growth of re-fracturing cracks process was studyied： the deflection of the path of existing fracture and the initiation of new fracture. The experimental results showed that： ① during the process of initiation of re-fracturing,existing fracture will reopen,initiate and deflect,and shear failure is the main failure form of the existing fracture deflection; 2when horizontal in-suit stress deflection occurs,it not necessarily produce new fracture： the smaller- K＇his,the easier the existing fracture deflect; the greater- K＇h is,the easier to produce new single wing fracture on surface of the existing fracture,and the critical condition of generating new fracture is- K＇h= 5 /7; 3 injection rate Q had a great influence on the new fracture： when Q is small,it is not easy to produce new fracture on surface of the existing fracture,only to produce deflection of the existing fracture; When Q is bigger,it is easy to produce single wing fracture on surface of the existing fracture.

关 键 词：地应力改变 已有裂缝偏转 新裂缝 物模实验 地应力差异系数K'_h 

分 类 号：TE319[石油与天然气工程—油气田开发工程]