This paper briefly describes the working principle of the self-excited oscillating nozzle and the experimental results of the pressure impulse characteristics and its frequency distribution under different ambient pressures. The transmitting law of the pressure fluctuation is introduced along the casing in both the axial and the radial directions. In addition, it presents the principle of water-injection with self-excited oscillation, the designation of the injection tool, and the field experimentation results. The field results indicate that the self-excited oscillating cavitation jets can be used as an effective way to prolong the production period of the well because the jets minimize formation block up. The average injection pressure was reduced by 2.1MPa, and the averaged volume of daily water injection for a single layer increased by 29m3. It can also prolong the water injecting time of the general waterinjecting well

High pressure water jet removing impurities in formations is a new way developed recently to increase oil production and injected-water. First of all, this paper presents the main reasons of formation plugging, the basic principles of high pressure rotating water jets removing impurities and the laws of the tool's rotating speeds, impact pressure and relations between impact pressure and nozzle stand-off. The field-test results obtained from over 500 oil and water-injection wells in Liaohe, Shengli, Zhongyuan, Huabei etc., indicate that this technology has such advantages as simplicity of use, cost effective, high success rate, wide adaptability, and significant effectiveness. From this, it is profitable and promising to increase production in highly water-cut oilfields.

采用离散涡方法模拟了两种不同形状哨嘴的喷嘴出口流场旋涡结构和压力分布。模拟结果表明，射流在喷嘴出口和哨嘴出口形成的旋涡结构在流场及其他涡元的作用下，向下游运动，在流场中某个地方形成低压区，这有助于诱发空化现象。对两种不同喷嘴的出口流场进行比较发现，哨嘴形状对形成的射流流场的旋涡结构有很大影响。因此，研究和应用空化射流必须考虑喷嘴出口哨嘴形状的影响。

自振空化射流是利用瞬态流和水声学原理亢进制而成的一种新型射流，本文研究了自振空化射流在常压及围压下的压力脉动特性及其参数影响规律。研究结果表明，在实验条件下各种风琴管喷嘴的压力脉动存在最优喷矩，无因次最优喷距都在8～14范围内，风琴管自振空化射流的冲击压力脉动峰值和脉动幅度分别比普通喷嘴高37%和24%；最大脉动幅度并不出现在射流轴心，而是偏离轴心一段径向距离；随着围压的增加，脉动峰值压力随着喷距的衰减速度明显加快，而脉动频率基本不随围压、压降和喷距的变化而变化，保持在1.38KHz左右。