【摘要】 针对承压防漏钻井液技术难题，为揭示井壁强化封堵裂缝微观机理，开展了井壁强化承压模拟实验研究。综合考虑井壁强化过程中裂缝闭合应力对裂缝开度的影响，建立了可变裂缝封堵模拟实验装置及评价方法，提出了最大封堵压差和等效封堵位置的定量化评价指标。修正的正态分布粒度匹配准则与常用的粒度匹配准则相比，最高可提升承压能力2.36倍。等效封堵位置与承压能力呈反比，修正的正态分布连续粒度准则可在裂缝入口端形成薄而致密的封堵层；尽可能提高承压封堵材料的强度可降低井筒压力波动的影响，增加井壁强化封堵材料的弹性可提高封堵层对动态裂缝的适应性；另外，适当增加封堵体系的悬浮稳定性，及合理降低其注入速度，均有利于承压封堵层形成及井壁强化效果改善。更多还原

【Abstract】 Laboratory simulation study was conducted on the strengthening of borehole walls to try to find a way of dealing with lost circulation under pressure and to reveal the micro-mechanisms of fracture plugging to strengthen the borehole walls. By comprehensively considering the effects of the closure pressure of fractures on their openings during borehole wall strengthening, a set of experiment apparatus was developed and a method for evaluating the plugging of fractures with variable openings established.Used with the apparatus and the evaluation method, two quantitative evaluation indicators, which are maximum plugging differential pressure and equivalent plugging position, were proposed. Compared with the commonly used particle size matching criterion, using the revised normal distribution particle size matching criterion, the pressure bearing capacity of a borehole wall can be increased by2.36 times at most. Equivalent plugging position is inversely proportional to pressure bearing capacity, and the revised normal distribution continuous particle size matching criterion can form at the entry of fractures a thin and dense plugging layer. Increase the strength of the plugging materials to a level as high as possible, the effect of the well pressure fluctuation can be reduced; increase the elasticity of the borehole wall strengthening plugging agents, the adaptability of the plugging layer to the dynamic fractures can be improved. Moreover, appropriately increasing the suspension stability of the plugging system and reasonably reducing its injection rate both are beneficial to the formation of the pressure bearing plugging layer and to the improvement of borehole wall strengthening.更多还原