中文摘要：

围压是石油工程中影响射流动力学特性的重要参数之一。应用高压井筒模拟试验装置进行了围压对常规连续射流、空化射流和磨料射流破岩效果影响的试验，最高围压达到20MPa。试验结果表明，围压对常规连续射流和空化射流破岩效果影响明显，破碎体积随围压的增大而减小，减小的速度随围压增大逐渐变缓；而对获得最大破碎体积的最优喷距影响不大，为3～5倍喷嘴直径，说明围压对射流基本结构特性影响不明显。当围压小于15MPa时，磨料射流射孔深度随围压的增大而近似呈线性减小。该试验可为射流参数的优选提供依据。

英文摘要：

Ambient pressure is one of important factors on hydrodynamic characteristics of water jet in petroleum engineering. Experiments were conducted to investigate the impacts of ambient pressure on rock breaking by common continuous water jet, cavitating jet and abrasive water jet impacts in a high pressure simulated wellbore with a maximum ambient pressure of 20MPa. Result shows that ambient pressures have a significant effect on rock breaking by common continuous water jet and cavitating jet. Rock breaking volume decrease with the increase of ambient pressure, the decreasing speed reduces with the increase of ambient pressure. Therefore there are slight impacts on obtaining the optimum standoff distance, about 3-5 times the nozzle diameter. This indicates that ambient pressure has small impacts on the basic structure of water jet. When ambient pressure is less than 15 MPa, rock hole depth perforated by abrasive water jet decreases quasi-linearly with the increase of ambient pressure. The study can provide some help to optimize jet parameters.