气体循环钻井井筒气量控制技术

Gas volume control techniques for circular gas drilling

柳贡慧 陶谦 李军

LIU Gonghui TAO Qian LI Jun

中国石油大学石油工程教育部重点实验室，北京　102249 北京联合大学，北京　100010

MOE Key Laboratory of Petroleum Engineering in China University of Petroleum, Beijing 102249, China Beijing Union University, Beijing 100010, China

通过对井筒气量控制的研究，可以提高循环钻进效率，并能有效降低设备压力控制的难度，为循环钻井施工提供合理的气量补充和排放方案，并为节点压力控制提供指导。依据封闭气体循环钻井工艺特点，开展针对循环钻井在不同注入条件下井筒压力的研究，利用压力分布研究成果，依据气体PVT理论，建立了井筒内部?环总气量计算模型，研究了在动态条件下井筒内气体质量分布。在此基础上，结合封闭气体循环地面设备控制要求，确定了井筒气量控制的合理区域。研究结果表明，随着井深的增加，单位进尺气量补充量增加，同时合理气量窗口逐渐变宽，如果井筒气量不足，井口将出现负压。

The study of wellbore gas volume control may be helpful to enhance the efficiency of circular drilling, reduce the difficulty in controlling the pressure of equipment, provide a reasonable plan to add or discharge gas for circular drilling, and guide the control of node pressure. Based on the characteristics of circular closed gas drilling, the study of wellbore pressure of circular drilling in different injection conditions is conducted. Using the research results of pressure distribution, on the basis of the gas P-V-T theory, the model to calculate the circular gas volume in the wellbore is set, and the gas mass distribution in the wellbore under dynamic conditions is studied. Based on the above-mentioned study, combined with the Ground equipment control requirements, the reasonable area of wellbore gas control is determined. Research results show that the unit footage gas volume increases with the increase of well depth, meanwhile, the reasonable gas window expands gradually. There will be negative wellhead pressure, if the gas volume in the wellbore gets insufficient.