天然气水合物钻探近井地层与井筒热量传递规律研究  

Study on the Heat Transfer Theory Between Near-Well Formation and Wellbore for Hydrate Drilling

作　　者：张恒瑞 刘伟 李牧 郝围围[1] 黄鹏鹏 李雅飞 ZHANG Hengrui;LIU Wei;LI Mu;HAO Weiwei;HUANG Pengpeng;LI Yafei(CNPC Engineering Technology R&D Company Limited,Beijing 102206,China;China University of Petroleum,Beijing 102249,China)

机构地区：[1]中国石油集团工程技术研究院有限公司 [2]中国石油大学(北京)

出　　处：《钻采工艺》2023年第3期29-36,共8页Drilling & Production Technology

基　　金：国家自然科学基金委员会重大项目课题“天然气水合物钻采井筒多相流动障碍形成机制与安全控制方法”(编号:51991363);中国石油天然气集团有限公司课题“天然气水合物钻采井筒多相流动障碍形成机制与安全控制方法”(编号:2022DQ0524)。

摘　　要：在天然气水合物钻探中,井筒温度变化易导致储层水合物分解,产生大量以甲烷为主的气体侵入环空。侵入气体随环空流体上返过程中,当环空温度压力等环境符合水合物二次生成条件时,水合物会在环空大量生成并附着井壁,堵塞环空引发井壁失稳、井喷等事故。文章研究了水合物钻探过程中井筒地层段的温度分布和热量传递规律,研究发现,环空流体温度降低易导致水合物生成,温度过高则会增大水合物储层的分解速率;钻井液入口温度越高,热量由环空传入地层的井段越长,反之越短;相较于低密度钻井液,高密度钻井液对井底温度影响更大;排量变化也会对井筒温度分布产生较大影响。因此,在水合物钻探过程中,通过对入口流体温度、排量和密度参数进行合理调节,避免发生储层水合物失控分解,对于保障水合物钻探过程井筒稳定,实现水合物安全钻采具有重要意义。文章阐明了热流量在井筒中的变化规律,通过计算井筒地层段中各区域换热速率和换热量的大小,为水合物钻探井筒温度监测提供理论支撑。同时也为后续的水合物得到井筒温度变化研究提供参考。In natural gas hydrate drilling,wellbore temperature changes may lead to reservoir hydrate decomposition and a large amount of methane-based gas influx into the annulus.In the process of influx gas flowing up with annular fluid,when the temperature and pressure of the annulus meet the conditions for secondary hydrate generation,hydrates will be generated in large quantities in the annulus and adhere to the wellbore wall,blocking the annulus and causing wellbore wall instability.In this paper,the temperature distribution and heat transfer law in the wellbore during hydrate drilling have been studied,it is found that the lower temperature of the annulus fluid can easily lead to hydrate generation,while the high temperature can increase the decomposition rate of hydrate reservoir and cause accidents such as well blowout and formation collapse;the higher the drilling fluid inlet temperature and the longer the well section where heat is transferred from the annulus to the formation;and vice versa,the shorter.Compared with low-density drilling fluids,high-density drilling fluids have a greater impact on the bottomhole temperature;the variation of discharge volume also has a greater impact on the wellbore temperature distribution.Therefore,it is important to avoid reservoir hydrate decomposition by reasonably adjusting inlet fluid temperature,discharge volume and density parameters during hydrate drilling to ensure wellbore stability during hydrate drilling and achieve safe hydrate drilling.The article elucidates the variation law of heat flow rate in the wellbore,obtains the magnitude of heat exchange rate and heat exchange in each region in the formation section of the wellbore,and can provide theoretical support for the temperature monitoring of hydrate drilling wellbore.It also provides a reference for subsequent studies on the temperature variation of hydrate drilling wellbore.

关 键 词：天然气水合物 井筒温度分布 热流量 近井地层 数值求解 

分 类 号：TE31[石油与天然气工程—油气田开发工程]