金属丝电爆炸冲击波对水泥环完整性的影响

随着电爆炸技术被应用于油井解堵、除蜡以及在近井地带构造微裂缝等作业,其在井下产生的冲击波对固井水泥环的影响不可忽视。为了研究电爆炸井下工具在作业过程中对水泥环完整性的影响,采用数值模拟方法,在AUTODYN中建立了套管-水泥环-岩石组合体模型,研究了冲击波载荷在组合体中的传播过程及其对水泥环的损伤。研究结果表明:在射孔区域,冲击波会经过射孔孔眼在液体中传播,并保持较高的压力,而在非射孔区域,冲击波经过套管后衰减较大;水泥环和岩石受到冲击波的作用时,损伤区域都是从射孔孔眼开始向外扩展,水泥环和岩石主要受冲击波的拉伸和剪切破坏,同时冲击波造成的套管变形也可能会造成水泥环损伤。研究结果对于电爆炸技术在石油行业的安全应用具有一定的指导作用。

Effect of Shock Waves Generated by Wires Electrical Exploding on the Cement Sheath Integrity

Along with the electrical explosion technique in oil well unplugging,dewaxing and generating of micro fractures in immediate vicinity of wellbores,the effect of the shock waves generated down hole on the cement sheath should not be neglected.In order to study the impact of the electrical explosion downhole tools on the integrity of the cement sheath during operations,the numerical model method was applied to establish the casing-cement sheath-rock composite model in AUTODYN,which was used to study the propagation process of the load of shock waves in the composite and the damage to the integrity of the cement sheath.Study results showed that:in the perforated zones,the shock waves could spread in the liquids through the perforated holes and maintain a higher pressure,while in zones without perforation,the shock waves will be significantly attenuated when passed the casings.When subject to the impact of the shock waves,all the damaged areas on the cement sheath and rock will be spread outwards from the perforated holes,and they are mainly damaged by the tensile and shearing forces of the shock waves.At the same time,casing deformation caused by the shock waves may also result in damages to the cement sheath.The study results would play certain role in guiding the safe application of electrical explosion techniques in the petroleum industry.