气体钻井岩屑运移破碎研究

Study on gas drilling cuttings breaking during the return process

朱忠喜 柳贡慧 岳达明 蒋记伟

ZHU Zhongxi LIU Gonghui YUE Daming JIANG Jiwei

长江大学石油工程学院，湖北荆州　434023 中国石油大学石油工程学院，北京　102249 胜利油田海洋钻井公司，山东东营　257000

Petroleum Engineering College of Yangtze University, Jingzhou 434023, China Petroleum Engineering College, China University of Petroleum, Beijing 102249, China Shengli Oilfield Sea Oil Drilling Company, Dongying 257000, China

气体钻井机械钻速较高，产生的岩屑较多，通常在井底岩屑颗粒较大，而从井口返出的岩屑颗粒较小，这说明岩屑在井筒内运移的过程中应该出现了二次破碎。针对这一现象运用颗粒碰撞破碎的相关理论进行了分析，给出了发生二次破碎的撞击速度计算方法，同时应用破碎过程矩阵和破碎粒度分布函数研究了岩屑在全井筒的运移时发生重复破碎的过程，计算结果表明，岩屑在井筒内破碎是由不均的体积破碎向均匀的表面破碎进行转变的过程，并且最终趋于稳定的粒度分布状态。

More cuttings produced during gas drilling due to higher mechanical penetration rate and the cuttings usually tend to be larger in the bottom and smaller uniform in size when back to the wellhead. It is indicating that cuttings should appear successive breaking within the process of migration. According to particle collision broken theories, the successive breaking phenomenon was analyzed, and the calculating method of crash velocity for the occurrence of secondary breaking was given in this paper. Meanwhile, the breaking process matrix and the particle size distribution function were applied to study the re-cracking process of cuttings migration in the whole wellbore. The calculating results show that the cuttings in the wellbore were broken first in the form of the uneven size volumetric fracturing and then progressively turned into the surface fracture of the uniform process, and ultimately was tending towards stable particle size distribution state.