大尺寸井眼固井活性冲洗液体系作用效能与机理研究

Study on the efficiency and mechanism of the active flushing fluid system for large-size borehole cementing

摘要:

针对超深井大尺寸井眼环空低返速工况下，常规冲洗液对钻井液滤饼冲洗效率低导致固井质量差的难题，本文通过高温高压动态清洗装置对比分析了不同混浆比例、冲洗速度、渗透率条件下，活性冲洗液在提升混浆强度、冲洗效率、促进二界面胶结强度发展方面的效能，并对冲洗后的固井二界面进行扫描电镜分析。结果表明：活性冲洗液体系的混浆强度较常规冲洗液可提升1倍以上；对比清水和常规冲洗液体系，活性冲洗液体系的滤饼冲洗效率达95%，具有显著的滤饼提升作用；模拟不同流速的冲洗情况发现，活性冲洗液体系在较低冲洗速度下的冲洗效率>90%。现场施工表明，活性冲洗液可有效提升混浆强度与固井二界面的胶结强度，从而显著提高大尺寸井眼固井施工质量，具有良好的应用前景。

Abstract:

To address the challenge of poor cementing quality caused by low filter cake removal efficiency under large-diameter borehole annulus conditions with low return velocity， this study employs a high-temperature， high-pressure dynamic cleaning apparatus to evaluate the effectiveness of active flushing fluid. Experimental investigations focus on three key parameters： mixing ratio， flushing velocity， and formation permeability， with particular emphasis on enhancing slurry strength， improving flushing efficiency， and promoting interfacial bonding strength at the second interface， moreover， scanning electron microscopy analysis was conducted to examine the cement-formation interface after flushing. The results are as follows： （1） the active flushing system achieves over 100% improvement in slurry strength compared to conventional flushing fluids； （2） with 95% filter cake removal efficiency， the active system shows significantly superior performance compared to water-based and conventional flushing systems； （3） after different velocity simulation， the active flushing fluid achieves over 90% flushing efficiency under low-velocity. The field applications confirm that the active flushing system effectively enhances both slurry strength and secondary interfacial bonding quality， thereby substantially improving cementing quality in large-diameter wells， indicating promising practical potential.