自进式高压水射流破岩数值模拟分析

A numerical simulation analysis of self-propelled high-pressure water jet rock breaking

针对应用于开发低渗透性、裂缝性和薄储层等油气藏的高压水射流技术,基于推导的水射流破岩的临界速度,设计了一种用于油田井下破岩的自进式高压水射流喷头,并应用湍流模型对喷头内部的水射流流场进行数值模拟分析,应用动力学模型对水射流破岩过程进行数值模拟分析。结果表明,入口压力30MPa时,喷头产生的水射流达到了破岩所需速度,能够实现破岩,并且破岩产生的破碎坑的内切圆直径大于喷头的最大外径,可实现自进式破岩,而且破岩过程中水射流速度是"脉动下降"的。这也说明所设计的喷头用于破岩是可行的,这种设计方法、建模方法和数值模拟方法在分析高压水射流破岩方面是可行的。

In light of the high-pressure water jet technology applied in oil-gas reservoirs in low-permeability,fracturing and thin reservoirs,and based on the derived critical velocity of water jet rock breaking,a kind of self-propelled high-pressure water nozzle used for borehole rock breaking was designed.The turbulence model was applied to conduct a numerical simulation analysis of the water jet flow field within the nozzle and the dynamic model was applied to conduct a numerical simulation analysis of the rock breaking process of water jet.The result shows that,when the entrance pressure was 30 MPa,the water jet produced by the nozzle reached the speed required by rock breaking and rock breaking could be achieved.The incircle diameter of the breaking pit produced by rock breaking was larger than the maximum outer diameter of the nozzle,so the self-propelled rock breaking could be achieved.Moreover,the water jet speed in the process of rock breaking was of 'fluctuating decrease'.This indicates that it is feasible for the designed nozzle to be used for rock breaking.The design method,modeling method and numerical simulation method are feasible in analysis of high-pressure water jet rock breaking.