钻井液密闭分离系统流程方案及装备配套

为解决开式钻井液循环分离系统不能满足在含硫地层实施欠平衡钻井作业要求而研制的钻井液密闭分离系统(密闭系统)是在含硫地层实施欠平衡钻井作业所必配的地面系统,也是在环境敏感地区进行欠平衡钻井或常规钻井避免环境伤害的重要装备。在对国外密闭系统配置方式和流程原理分析的基础上,提出了"两步分离"式密闭系统流程方案,即从井内返出的含有硫化氢的钻井液首先通过密闭分离装置将油、气以及大颗粒的岩屑清除,同时向密闭分离装置中注入除硫剂,以确保硫化氢清除干净;然后再将经分离后不含硫化氢的钻井液,排入常规固控系统以维护和调节钻井液性能,再由钻井泵泵入井内进行循环。并制订了井内返出钻井液中硫化氢含量突然升高时的处理措施;阐述了"两步分离"式流程方案所需的四相分离器、钻井液缓冲罐、真空除气器、密闭式带压取样装置、密闭式岩屑存储装置等配套装备的结构原理和研究现状,为国内钻井液密闭系统的研究和应用提供了技术思路。

A flow scheme and equipment matching technology of a drilling fluid closedloop system

The drilling fluid closed loop system is a necessary ground system for underbalanced drilling in the formations containing sulfur, and also an important equipment for underbalanced or conventional drilling under environmentally sensitive area to protect the formations from damage. Based on analysis of planning modes and flow principles of foreign closed loop systems, a scheme of "two step separation" closed loop system is put forward. First, the drilling fluid containing H2S reversing out from the well is screened by a closed separation device, and the oil, gas and large particle rock crumb are cleared away; meanwhile, the desulfurizer is injected into the closed separation device in order to totally get rid of H2S. Then, the drilling fluid without H2S after the first separation is led into a conventional solid control system to maintain and adjust its performance, and finally, the fluid is pumped to the well for circulating by the drilling pump. In addition, emergency treatment measures are planned to be taken in such a case when the H2S content in drilling fluid reversing out from the well increases abruptly; the structure principles and research status of four phase separators, drilling fluid buffer tanks, vacuum degasifiers, closed sampling units with pressure, closed storage devices for rock crumb and other equipments required in the "two step separation" closed loop system are introduced in detail, providing a guideline for further study and application of drilling fluid closed loop system in China.