窄密度窗口及小间隙超深井尾管固井技术

针对西南油气田超深井五探1井φ168.3 mm尾管悬挂固井存在钻井期间漏失严重，井深、井底温度高，大段盐膏层、油基钻井液与水泥浆污染严重、后期作业井筒温度压力变化影响水泥环密封完整性等难题。采用低密度高强度韧性微膨胀防窜水泥浆体系，通过优化浆柱结构，控制井底动态当量密度与钻进时井底动态当量密度相当的平衡压力固井等配套工艺技术，有效防止了固井施工漏失，解决了水泥浆与油基钻井液污染严重的问题，确保了固井施工顺利，固井质量合格率100%，优质率99.8%，为深井窄密度窗口、油基钻井液固井提供了技术支撑。 

Liner Cementing in Ultra-deep Wells with Narrow Drilling Window and Small Annular Clearance

Several difficulties have been met in cementing the φ168.3 mm liner (with hanger) in the ultra-deep well Wutan-1 in Southwest Oil and Gas Field, such as severe mud losses during drilling, deep well, high bottom hole temperature, long salt rock formation, severe contamination to the oil base mud and cement slurry used, and influence on the integrity of cement sheath by changing wellbore temperature in later-stage operations. Using low density high strength micro-expansion anti-channeling high toughness cement slurry with optimized column structure, the dynamic ECD at the bottom of the hole during cementing was maintained at almost the same level of the dynamic ECD at the bottom of the hole during drilling. These measures effectively prevented wellbore fluid losses from happening during well cementing, and minimized contamination to the cement slurry and the oil base drilling fluid. The job quality of cementing was 100% certified, and 99.8% of the job with high quality. This technology has provided technical support to cementing deep wells with narrow drilling windows and drilled with oil base drilling fluid.