岩土工程学报2016，Vol.38Issue(8)：1466-1472,7.DOI:10.11779/CJGE201608014
气体钻井低温破岩机理分析
Mechanism of cryogenic rock failure in gas drilling
摘要
Abstract
The factors contributingtohigh penetration rate of gas drilling are complex.The isentropic flowis generated when gas passes through bit nozzle during gas drilling. This phenomenon will lead to cryogenic effects, and then the resulted thermal shock stress at bottom hole rockwill reduce the rock strength, contributing to the role of the rock failure. First,amodelforthe temperature distribution of bottom hole rock under asymmetric coolingis established. The three-dimensional dynamic thermal shock stress distribution modelis established based on the temperature field. Then, the change of the rock cohesionis analyzed by using the Mohr-Coulomb criterion. The results demonstrate that as the temperature decreases, the strength of rock is greatly reduced, resulting in increased ROP.Finallythe liquid nitrogen cooling tests andreal-time measurements of acoustic wavesare conducted to verify the above theory. Thefirst wave amplitude hasa dramatic delay, which illustrates thatthe cooling has an important impact on the internal structureofrock.The mechanism of rock failure under dynamic low temperature in gas drilling isclearly depicted.关键词
气体钻井/低温/热应力/莫尔-库仑准则/声波试验Key words
gas drilling/low temperature/thermal stress/Mohr-coulomb criterion/acoustic test分类
建筑与水利引用本文复制引用
杨顺吉,李军,柳贡慧..气体钻井低温破岩机理分析[J].岩土工程学报,2016,38(8):1466-1472,7.基金项目
国家自然科学基金面上项目 （）
