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气体钻井在川渝地区大幅度地提高了机械钻速,受到钻井界的青睐,但气体钻井结束替入常规水基钻井液后普遍出现了严重的井壁失稳难题,导致了长时间大段划眼复杂情况的频繁发生。为此,从分析气体钻井替入钻井液后井壁失稳的水敏性原因入手,提出了解决井壁失稳的技术思路,即将润湿反转防塌技术—低渗透防塌技术—低活度防塌技术三者有机集成在一套钻井液体系中,形成具有“低润湿反转角、低渗透、低活度”特点的“三低”水基钻井液防塌技术,并在室内对获得的“三低”水基钻井液成果配方进行了定量的防塌效果评价。研究结果与现场试验表明,“三低”水基钻井液能够很好地解决气体钻井结束替入水基钻井液后出现的井壁失稳难题;它能在30min内使泥页岩地层发生明显润湿反转和惰性化反应;在180min内能彻底密封裂缝,并在泥页岩表面形成致密疏水涂层;无论是在短期防塌,还是在长效防塌方面都具有显著的效果。适合在类似川中地区的气体钻井中推广应用。
Gas drilling has greatly increased the ROP in Sichuan and Chongqing, which is favored by the drilling community. However, the serious failure of the borehole wall generally occurs after gas drilling has ended into the conventional water-based drilling fluid, resulting in a long period of large section The complicated situation of zhongye frequently occurs. Therefore, starting from the analysis of the reason of the water-sensitivity of the borehole wall instability after the gas well is drilled into the drilling fluid, a technical solution to the instability of the borehole wall is proposed. That is to say, the wetting reversal anti-collapse technology - low-permeability anti-collapse technology Activity anti-collapse technology three organic integration in a drilling fluid system, the formation of a “low wetting reversing angle, low permeability, low activity ” “three low ” water-based drilling fluid collapse Technology, and quantitatively evaluated the anti-collapse effect of the obtained “three low” water-based drilling fluid formulations in the laboratory. The research results and field tests show that the “three low” water-based drilling fluid can well solve the wellbore instability problem after the gas drilling is completed for the water-based drilling fluid; it can cause shale formation within 30 min Obvious wetting reversal and inerting reaction; completely seal the cracks within 180min and form a dense hydrophobic coating on the surface of the shale; and it has a remarkable effect both in short-term collapse prevention and long-term collapse prevention. Suitable for gas drilling similar to the Central Sichuan area to promote the application.