石油学报 ›› 1999, Vol. 20 ›› Issue (4): 56-60.DOI: 10.7623/syxb199904011

• 油田开发 • 上一篇    下一篇

地层压裂时岩石残余裂缝的形成

李文魁, 周春虎   

  1. 西安石油学院
  • 收稿日期:1997-11-10 修回日期:1998-06-12 出版日期:1999-07-25 发布日期:2010-05-21
  • 作者简介:李文魁,男,1965年II月生.I9&9年毕业于西南石油学院.现任西安石油学院副教授.通讯处:陕西省西安市.邮政编码:710065.

THE FORMATION OF REMAINING CRACK IN FRACTURING

Li Wenkui   

  1. Xi'an Petroleum Institute
  • Received:1997-11-10 Revised:1998-06-12 Online:1999-07-25 Published:2010-05-21

摘要: 从理论与实验两方面,分析了岩石加载与卸载时不同的变形规律,加载和卸载时岩石的变形是不可逆的.当P/σE2/E1取得某一确定值时,在卸去边界上的载荷后,裂缝不会完全闭合,结果将产生残余变形.实测的地层岩石加载/卸载σ~ε曲线分析得出,卸载时测的杨氏模量E2高于加载时的杨氏模量E1的值;且卸载时测得的泊松比值也高于加载时测得的泊松比值.表明了卸载过程中原生存在于岩样中的孔隙和裂隙在加载过程中造成的闭合不能完全得到恢复,卸载后岩样形成了残余裂缝.实践也表明,水力压裂中不用砂支撑裂缝,有时也是有效的;气体压裂由于工艺方面的原因,至今也没有能进行加砂的气体压裂,然而施工的井均不同程度见到增产/增注效果.因此,实践证实高速对裂缝表面的冲刷及岩石的不可变形客观存在.

关键词: 岩石, 加载, 卸载, 试验, 地层压裂, 残余裂缝

Abstract: The different deformation regulations of rock under loading/unloading is analyzed in this paper basing on theory and ezperiment, the rock deformation under loading/unloading is irreversible.The fracture can not be fully closed and will produce remaining deformation, when the loads acting on bound are discharged and P/σ together with E2/E1 gains certain value.The Young's Modulus and Poisson's Ratio under unloading are higher than those under loading by analyzing real σ~ε curves of rocks.It shows that remaining cracks have been produced in rock samples.The site practices also prove that the irreversible deformation of rocks is an objective reality.

Key words: rock, loading and unloading, test, formation fracturing, remaining crack