超临界CO2射流特性数值模拟研究

在利用超临界CO2射流开采非常规油气资源过程中,工况参数的变化对超临界CO2射流作业效果有较大影响。为揭示参数变化对超临界CO2射流特性的影响规律,利用计算流体力学方法模拟了不同喷嘴直径、注入排量、围压和流体温度下超临界CO2射流特性并进行了对比分析。研究结果表明:喷嘴直径和注入排量对超临界CO2射流冲击性能的影响明显强于围压和流体温度;超临界CO2射流等速核长度随喷嘴直径、注入排量和温度的增加而增加,随围压的增加而减小,但围压的增加也使超临界CO2射流流体密度增大,有利于射流冲击作业;围压和流体温度对超临界CO2淹没射流和淹没水射流速度特性的影响存在明显差别。研究结果进一步加深了对超临界CO2射流特性的认识,为超临界CO2射流技术在钻井和喷射压裂作业中的应用提供了理论参考。

Numerical Simulation of Supercritical CO_2 Jet Behavior

In exploiting unconventional oil and gas resources by supercritical CO2 jet,the change of working condition parameters has a great influence on the effect of supercritical CO2 jet operation. To understand the influence of parameter variation on the supercritical CO2 jet behavior,the computational fluid dynamics method is used to simulate the supercritical CO2 jet behavior under different nozzle diameter,injection displacement,confining pressure and fluid temperature. Comparative analyses indicate that: the influences of nozzle diameter and injection displacement on the performance of supercritical CO2 jet are stronger than that of confining pressure and fluid temperature. The length of constant velocity core of supercritical CO2 jet increases with nozzle diameter,injection displacement and temperature,but decreases with confining pressure. The increase of confining pressure enlarges the density of supercritical CO2 jet fluid,which is beneficial to jet impact. The influence of confining pressure and fluid temperature on the supercritical CO2 submerged jet and water submerged jet is significantly different. The study deepens the understanding of supercritical CO2 jet behavior,and provides a theoretical reference for the application of supercritical CO2 jet technology in drilling and jet fracturing operations.