气体钻井携岩关键点多相流动规律研究

Research on multiphase flowing law of cutting transportation key point in gas drilling

肖国益 赵向阳 孟英峰 朱化蜀 练章华 李皋

XIAO Guoyi ZHAO Xiangyang MENG Yingfeng ZHU Huashu LIAN Zhanghua LI Gao

西南油气公司工程技术研究院，四川德阳　618002 西南石油大学“油气藏地质及开发工程”国家重点实验室，四川成都　610500

Engineering technology Insititute of Southwest Branch, SINOPEC, Deyang 618002, China State Key Laboratory of Oil and Gas Geology and Exploration，Southwest Petroleum University, Chengdu 610500, China

气体钻井环空井径的扩大与缩小、部分泥包、变径截面等对环空流场和岩屑运移的影响很大。建立了气体钻井携岩关键点多相流动物理模型、数学模型，采用室内大型流动实验、CFD数值模拟和现场实例验证的手段，对携岩关键点进行多相流动分析发现，变径截面─钻铤与钻杆过渡点、套管井段与裸眼井段的过渡点、井径的扩大与缩小井段，钻杆某处的泥包点，这些点由于边界层分离而形成的尾涡回流区，岩屑在这些回流区容易滞留、堆积，在这些回流区容易导致携岩不畅。气体流经钻杆与钻铤交接面处，气体的压力、速度都相应减小，在此处的气体携岩动能最小，环空岩屑浓度最大。最小气量的选择应该以携岩关键点处所需的最小能量为一个参考依据。

During gas drilling, the increase or decrease of annular diameter, partly balling up and section changing have great effect on annular flow field and cutting transportation .Through multiphase flow analysis and numerical simulation at key point of cutting transportation it was found that cutting was easy to hold up and pile up at the transition point of drilling collars and drilling pipe, the transition point of casing and open hole section, the increase and decrease diameter section and the balling up point, as they formed reflow area by the boundary layer separation. These areas may lead to cutting transportation difficult. While gas flew through cross section of drill collar and drill pipe, gas pressure and speed decreased and cutting transportation capacity is minimum, while the annular cuttings density is maximum. The minimum gas rate requirement for cutting transportation should be based on the minimum capacity at the key points.