M3井井漏原因分析及录井监测预防方法

Cause analysis of lost circulation and mud logging monitoring and prevention methods in Well M3

在多年录井实践及综合研究的基础上,以M 3井下技术套管后循环钻井液时发生的井漏为典型实例,系统分析研究了钻井液静液压力、正常钻进时环空压耗、套管外循环钻井液时环空压耗等求解公式和方法,求证出在套管外循环钻井液时,由于环空较小,较大的钻井液排量产生了较大的环空压耗,是导致井漏的主要原因。就如何借助综合录井实时采集参数多、智能化等优势,实时监控、预测地层压力、地层破裂压力,实时计算出不同钻井液排量下的环空压耗,实时预测发生井漏的最小钻井液排量等,提出相应解决思路。由此得出的结论表明,充分利用好工程录井技术,可减少井漏事故的发生。

On the basis of years′ mud logging experience and study,taking the lost circulation of drilling fluid after running casings in Well M 3 for an example,the paper analyzed the solution formulas and methods on hydrostatic pressure of drilling fluid,annular pressure loss while normal drilling and circulating drilling fluid outside the casings.It proved that the higher drilling fluid displacement will cause higher annular pressure loss while circulating as the annulus is too small.This is the primary cause of lost circulation.Moreover,some viewpoints of using the comprehensive logging unit correctly are given in this paper,such as real-time monitoring and predicting the formation pressure and formation fracture pressure,calculating the annular pressure loss in different drilling fluid displacements,predicting the minimum drilling fluid displacement while lost circulation,and so on.A conclusion can be drawn that the lost circulation will be reduced by making the best use of mud logging technology.