可控复合脉冲爆燃压裂动态加载模型

摘要

A new ignition technique was proposed for downhole blasting fracturing using high energy propelants, in which a high speed and a low speed propellant are loaded in series with simultaneous ignition in a central tube. The new technique can avoid the problems of the currently ones that use single speed and one-pulse propellant for its instability and ignition-delay. Based on the different deflagration speed equations, the mass and energy conservation equations, a dynamic gas loading model of the multi-pulse deflagration was established, which can be used to simulate the dynamic loading process with different ratios of the propellants. The results show that the packaged propellants work well with the dynamic loading of the combination of the high and low speed propellants, in which a small quantity of the high speed propellant is ignited to generate a high pressure for initializing fractures, and large amounts of the low-speed propellant are ignited for the enlargement and extension of the frac-tures. It is suggested that, in order to achieve initializing fractures quickly and the protection of the casing, the usage of the high deflagration speed propellant can be reduced, while the quantity of the low deflagration speed propellant can be increased.%针对单级火药爆燃速度单一、延迟点燃连接装置稳定性欠佳的问题，提出高低燃速火药串联装配、中心管同步点燃新型工艺，进而基于不同爆燃速度火药的燃速方程，借助火药结构几何模型、质量守恒方程、能量守恒方程和气体状态方程建立多级脉冲组合火药爆燃加载模型，据此定量计算不同比例组合火药爆燃加载压力与时间的动态变化。结果表明：组装火药可有效协同高低燃速火药爆燃加载优势，既可用少量高燃速火药迅速产生高压破裂储层，又不会产生过大峰值压力破坏套管，同时又能利用大剂量低燃速火药长时有效延伸裂缝；在确保迅速破裂储层基础上，尽量减少高速火药量、增加低速火药量，以便建立施工安全和措施效果的有效平衡，同时可在套管安全的前提下扩大整体装药量，提高措施效果。