DEVELOPMENT OF AN IN-SITU WATERJETS SYSTEM FOR PERFORATION

为了研制高压水射流原位射孔增产系统，在压力容器中进行了氯乙烯套管射孔实验和冲击压力测试。在此基础上，设计了现场射孔系统，并在南关东气田某注水井进行了现场初步试验，主要结果如下：1.穿孔面积在环境压力为驱动压力的2%至3%时达到最大。当喷距增加时，未发生穿孔的最大环境压力降低，而在低环境压力下穿孔面积增加。喇叭形喷管比传统的直喷管更有效。15 °角的喇叭角在穿孔面积和最大环境压力下都表现最好。冲击压力的动态分量在环境压力下切割材料时起着决定性的直接作用。在水射流表现出高性能的条件下，冲击压力的功率谱密度具有峰值，其频率从低环境压力的几kHz到高环境压力的约23 kHz变化。动态分量似乎与在环境压力下切割材料的有效空化有关。噪声的动态特性与冲击压力的动态特性相似，这使得我们可以通过测量压力容器外的噪声来检测材料切削过程中的动态冲击力.初步的现场测试已经成功进行。根据研究结果，设计了一套现场水射流射孔系统，对一口注水能力差的注水井进行了套管射孔，使注水能力得到了大幅度恢复。

To develop an in-situ perforation system for increasing natural gas production by using high pressure waterjets, laboratory perforation tests on a vinyl chloride casing pipe and measurements of impact pressure were carried out in a pressure vessel. Based upon the test results, an in-situ perforation system was then designed and preliminary in-situ tests were carried out for an injection well in the South Kanto natural gas field.The main results were summarized as follows :1. The perforated area becomes maximum at an ambient pressure of 2 to 3% of the driving pressure. When the standoff distance is increased, the maximum ambient pressure where no perforation occurred decreases and the perforated area increases at low ambient pressures. Horn nozzles are more effective than a conventional straight nozzle. A horn angle of 15ﾟ performs best both in perforated area and in the maximum ambient pressure.2. Dynamic components of impact pressure play a decisive and direct role in cutting materials under ambient pressure. Under the conditions where waterjets show high performance, the power spectral density of impact pressure has a peak, the frequency of which varies from a few kHz at low ambient pressures to about 23 kHz at high ambient pressures. The dynamic components seems to be related to effective cavitations for cutting materials under ambient pressure. The dynamic characteristic of noises is similar to that of impact pressure, which enables us to detect dynamic impact force during cutting materials by measuring noises outside a pressure vessel.3. Preliminary in-situ tests were conducted successfully. The injectivity of a poor injection well was recovered drastically by perforating the casing pipe with an in-situ waterjets system, which was designed according to the results in this study.