环空流体吸入式自激振荡脉冲射流大涡模拟研究

Large eddy simulation of self-oscillation pulsed water jet drawing in annulus fluid

发展新型破岩钻井技术对于促进油气田高效开发具有重要意义,高压水射流是提高破岩钻井效率的一个重要手段,脉冲射流是一种高效射流形式。为了充分利用井底水力能量,提出了一种环空流体吸入式脉冲射流的技术构想。基于自激振荡原理设计了相应射流调制工具,并对工具的流场和动力学特性进行了大涡模拟研究。研究结果分析揭示了环空流体吸入式自激振荡脉冲射流调制的机理,并发现合理的水力结构可以在振荡腔内实现局部负压,使得环空流体被吸入,参与调制生成高效脉冲射流。与非吸入式脉冲射流相比,吸入式脉冲射流振荡更加剧烈,破岩能力更强。研究结果得到了实验验证,为实际钻井工具的研制和相关工艺技术的开发提供了依据。

It is of great significance that developing new rock breaking drilling technology to promote efficient exploit of oil field. High pressure water jet drilling technology is an important method to promote the rock breaking drilling efficiency, and pulsed water jet is such a kind of high efficiency water jet. In order to take full advantage of hydraulic energy in bottom hole, a concept of new type of pulsed water jet drawing in annulus flow, is put forward. The pulsed water jet modulation tool is designed based on the self-exciting principle, and the large eddy simulation is adopted to simulate the flow field and the dynamic characteristics in this tool. This simulation shows the modulation mechanism of self-exciting pulsed water jet drawing in annulus flow. Partial negative pressure could be achieved in the oscillating cavity if the reasonable hydraulic structure is applied. The negative pressure formed in the drawing entrance of the oscillating cavity provides assurance to automatically draw enough fluid into annulus flow, which takes part in modulating the efficient pulsed water jet. The amplitude is larger and the rock breaking capacity of the pulsed water jet drawing in annulus flow is much better than the case non-drawing in annulus flow. The simulation results are verified by the lab experiment. The above research lays the foundation for the development of drilling tools and related technology.