精细控压钻井控压响应时间浅析

Analysis on pressure controlling response time of delicate controlled pressure drilling

余金海 孙宁 刘健

YU Jinhai SUN Ning LIU Jian

西南石油大学，四川成都　610500 中国石油集团钻井工程技术研究院，北京　100195

Southwest Petroleum University, Chengdu 610500, China Drilling Research Institute of CNPC, Beijing 100195, China

精细控压钻井通过PWD随钻测压、计算机控制、回压泵和节流阀等闭环调节井口回压，精细控制井底压力，以满足安全、快速钻井的需要。判断精细控压钻井系统性能高低的一个重要指标就是压力控制的响应时间。短的控压响应时间可以很快平衡井底压力变化，维持钻进在井底压力基本恒定下进行。以回压从井口传到井底的时间为研究对象，建立了回压在环空传播速度的计算模型，分析了影响回压传播速度的主要因素钻井液密度、气体含量和岩屑含量，并以控压钻井实例数据计算为例、分析了精细控压钻井的控压响应时间，为精细控压钻井提供理论支持。

Through PWD, surface computer control system, back pressure pump and choke etc., delicate controlled pressure drilling system could adjust the wellhead back pressure and delicately controls the bottom hole pressure to meet the needs of safe and fast drilling. The important index reflecting the performance level of delicate controlled pressure drilling system is the response time. Short time can quickly balance off bottom hole pressure variation and keep drilling basically under constant bottom-hole pressure. The pressure controlling response time is consisted of three parts: PWD signal transmission time, the time from analyzing signal to adjusting wellhead back pressure by surface control system and the time of back pressure propagating from wellhead to bottom. This paper regarded the third part—the time of back pressure propagating from wellhead to bottom, as the research object. The computational mode of back pressure propagation velocity in annular was established, and the main factors affecting the velocity were analyzed, which were drilling fluid density, gas content and cutting content. Field data were used to calculate and analyze the pressure controlling response time. Finally theoretical supports were provided for delicate controlled pressure drilling.