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由于油管传输的负压射孔方法在保证孔眼清洁、降低完井时间和减少增产作业等方面具有显著的优越性,故该方法的使用日趋增加。利用径向流贝雷砂岩岩样,可以确定完井过程中岩石压力与井筒压力之间随时间变化的压差所引起的射孔特性。所研究的主要射孔特性,即径向流动比 R_(FR)定义为:已射孔岩样的流量与未射孔岩样的流量之比。射孔流动试验所涉及的压差,从500Psi(3450KP_a)的正压到1000Psi(6900KP_a)的负压时,采用瞬时的或延迟的反向冲击。当压差值从500PSI(3450KP_a)的正压改变到1000PSI(6900KP_a)的负压时,径向流动比R_(FR)受到很大的影响。进行反向冲击的径向流动比 R_(FR),比无反向冲击的流动比 R_(FR)大50%～80%。进行反向冲击后的射孔孔眼体积可以增加55%,这说明反向冲击部分地消除了压实带和污染带的渗透率降低效应。负压射孔(-1000Psi)并进行反向冲击所增加的孔眼体积是正压射孔(+500Psi)且不进行反向冲击时的孔眼体积的四倍。这样看来,负压反向冲击射孔(瞬时或延迟的反向冲击)似乎可以改善聚能射孔的流动特性,因为它减少了低渗透压实带的厚度,并且增加了孔眼的表面积。
Because of the negative pressure perforation method of tubing transmission has obvious advantages in ensuring eyelet cleaning, reduce completion time and reduce stimulation production, so the use of this method is increasing. Using radial flow Berea sandstone samples, perforation characteristics due to the pressure differential over time between rock pressure and wellbore pressure during well completion can be determined. The main perforating characteristics studied, namely the radial flow ratio, R_ (FR), is defined as the ratio of the flow rate of a perforated rock sample to that of an un-perforated rock sample. The pressure differential involved in the perforating flow test uses an instantaneous or delayed reverse impact from a positive pressure of 500 Psi (3450 KP a) to a negative pressure of 1000 Psi (6900 KP a). When the differential pressure changes from a positive pressure of 500 PSI (3450 KP a) to a negative pressure of 1000 PSI (6900 KP a), the radial flow ratio R FR is greatly affected. The radial flow ratio R_ (FR) for reverse impact is 50% ~ 80% larger than the reverse flow rate R_ (FR). The perforation perforation volume after reverse impact can be increased by 55%, indicating that the reverse impact partially eliminates the permeability reduction effect of the compacted and contaminated zones. Negative pressure perforation (-1000 psi) and reverse impact increased the volume of the perforation to be four times the volume of the perforation at the positive pressure perforation (+500 psi) without reverse impact. As such, negative pressure reverse impact perforation (transient or delayed reverse impact) appears to improve the flow properties of the shaped perforation as it reduces the thickness of the low-permeability compacted belt and increases the perforation’s surface area.