可钻式贴堵工艺中膨胀水泥机械性能参数的优选

Mechanical Parameters Optimization of Expansive Cement in Drillable Pasting and Plugging Process

可钻式贴堵工艺是一种适用性强、封堵可靠性高、后期处理方便的新型调整层系封堵作业技术,其常选用膨胀水泥来改善封堵效果。为了预防膨胀力挤坏可钻式贴堵管,采用有限元数值模拟方法,研究了膨胀水泥和地层的机械性能参数对贴堵管中应力的影响规律,优选了膨胀水泥的机械性能参数范围。结果表明:膨胀水泥膨胀率对贴堵管内应力的影响最大,次之是膨胀水泥的弹性模量,膨胀水泥的泊松比、地层的弹性模量和泊松比的影响较小。膨胀水泥膨胀率越大,贴堵管内的应力越大,且环空中膨胀水泥的体积越大,应力增长速率越大;随着膨胀水泥弹性模量的增大,贴堵管内的应力先增大后减小。无缺失和原套管缺失两种情况下贴堵管挤毁的可能性较小,原套管和水泥环都缺失时最可能挤毁贴堵管。优选膨胀水泥的膨胀率为0.5%,其它机械性能参数可在任意范围内变化。研究结果对可钻式贴堵工艺的成功应用具有重要的指导意义。

The drillable pasting and plugging process is a new technology for plugging in adjusting layer, it has high adaptability, high reliability and is convenient for post-processing. The expansive cement is always used to improve the sealing effect in this process. In order to prevent the drillable tube from being destroyed by inflation force, the effect of mechanical parameters of expansive cement and formation on stress in pasting and plugging tube was studied by the finite element numerical simulation method, and the mechanical parameters range of the expansive cement were optimized. The results showed that the expansive ration had the greatest effect on stress in pasting and plugging tube and the elastic modulus of expansive took the second place. The effect of Poisson＇s ratio of expansive cement, the Poisson＇s ratio and the elastic modulus of formation was small. The bigger the expansion ratio of expansive cement, the greater the stress in the pasting and plugging tube. The larger the volume of the expansion cement in annular space, the greater the stress growth rate was. With the increase of the elastic modulus of expansive cement, the stress in the pasting and plugging tube increased and then decreased. The possibility of tube collapse was small under no deficiency and casing deficiency. The tube was easily destroyed as the casing and cement sheath both had deficiency. The optimized expansion ratio of cement was 0.5%, and other mechanical parameters can change in any range. The research results are of great significance to the successful application of the process.