塔河油田托甫台地区奥陶系碳酸盐岩储层安全压力窗口窄，储层以裂缝、缝洞为主，钻井中易漏、易涌。TP127H井是该区一口碳酸盐岩超深水平井，钻至井深6914.39 m，漏失钻井液量1538.67 m3，水平段钻进钻遇多个溶洞，为安全顺利钻至设计井深，对该井实施了欠平衡钻井工艺。论证了该井欠平衡钻井的可行性，分析了欠平衡钻井技术的钻井液密度、井口控制压力和井底压力，研究成果应用于TP127H井欠平衡钻井施工中。应用结果表明，该技术有效地解决了TP127H井漏失难题，对同类油藏的钻井施工提供了借鉴。%The Ordovician carbonate reservoir in Tuoputai Area of Tahe Oilifeld, the safety pressure window is narrow, the reservoir is dominated by caves and fractures and it is easy to cause lost circulation or kicking. TP127H well is an ultra-deep carbonate horizontal well in this area, which is drilled to the depth of 6914.39 meter with leakage of 1 538.67 m3. Several dissolved caverns were met dur-ing horizontal drilling. To drill to the design depth successfully, under-balanced drilling is performed for this well. This paper discusses the feasibility of under-balanced drilling of this well; analyzes the density of drilling lfuid, wellhead control pressure and bottom hole pressure in the under-balanced drilling; and the achievements are applied in under-balanced drilling of TP127H well. The results of ap-plication show that the technology is able to solve problem of lost circulation of TP127H well and also to provide references for drilling in the similar reservoirs.
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