The Pressure Fluctuating Tool (PFT) utilizes a fluidic oscillator to create pulsating pressure for breaking down perforations. The maximum pressure fluctuations produced by the oscillator can be as great as 1500 psi (10,300 kPa) above and below downhole ambient pressure with frequency ranging from 140 to 160 cycles per second. Pressure fluctuations are greatest in the primary oscillation zone located at the center of the 26 foot.(7.92m) long tool. The pressure fluctuations decrease to essentially zero within 8 feet (2.43m) above and 8 feet (2.43m) below the primary oscillation zone. These fluctuations break down the perforations and formation face.

As perforations are opened, the casing annulus is effectively exposed to a larger fluid volume, causing the amplitude and frequency of fluctuations to decrease. These changes are monitored by instrumentation at the surface to determine when breakdown is complete and the tool can be moved to the next section of perforations.

This paper will describe the operation of the PFT and report data collected in field applications.

Keywords:
perforation, frequency, inertance tube, pft, fluidic oscillator, pressure fluctuation, instrumentation, completion installation and operations, fluctuation amplitude, fluctuation
Subjects:
Formation Evaluation & Management, Perforating, Completion Installation and Operations, Completion Operations
Copyright 1985, Society of Petroleum Engineers
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