大口径瓦斯抽排井注浆固管过程套管稳定性分析

为了研究大口径瓦斯抽排钻井注浆固管过程中套管的稳定性,应用伯努利方程分析了注浆固管过程中浆液的动压力的变化规律。分析认为：注浆固管期间,若注浆管内过流面积小于套管与孔壁之间的过流面积,随着泵量的增加,导致套管外流体压力增加;当套管外与套管内压力差大于套管抗外挤强度时,套管发生失稳（瘪管）。结合工程实例,对套管失稳机理进行分析,提出了在固管过程中要控制泵量的建议。

Casing Stability Analysis during Large Diameter Gas Drainage Well Grouting and Casing Fixation Process

To understand casing stability during large diameter gas drainage well grouting and casing fixation process, using the Bernoulli equation analyzed dynamic pressure variation pattern during the process. The analysis has considered that during the grouting and casing fixation process, if the flow area in the grouting pipe less than the flow area between casing and wall, along with the increasing of pump capacity, bring on increasing of fluid pressure outside the casing. If the pressure difference between casing outside and inside more than casing crushing resistance, casing will be instability （collapsed）. Combined with project examples, carried out casing instability mechanism analysis, put forward a suggestion on pump capacity control during grouting and casing fixation process.