The Research On Intermittent-type Control Signals Of High-power Ultrasonic And Measurement System Of Downhole Liquid-level

The development of oil and gas fields in China has entered the mid-later period atcurrent. Oil wells of water-injection development are stratum block seriously.Block-removing is one of the effective ways to increase oil. This paper realizes thehigh power ultrasonic intermittence-type of oil production equipment, whichgenerates strong impact force of vibration. The pore fluid in reservoir produces a largenumber of cavitation bubbles and the particles which jam in pore throats have greatacceleration. As a result, this way improves the permeability of the formation,increases the water injection ability and the produced fluid volume of wells. The highpower ultrasonic intermittence-type of oil production equipment provides an effectivemean for block-removing.This article realizes a control circuit to generate two intermittent-type of PWMcontrol signals and we set the STM32singlechip as the core device. These twosignals, whose phase difference is180°and the deadtime is3s. When accessingthe control circuit to this high-power ultrasonic stimulating system, it can operateproperly and stably. The system has primarily satisfied the demand of industrialapplication.High power ultrasonic transducer applies piezoelectric crystal to realize theconversion between electro and acoustic. The transducer makes of piezoelectriccrystal has multiple vibration modes and each mode corresponds to a resonantfrequency which has the highest efficiency of acoustic-electric or electro-acousticconversion. In order to get the biggest ultrasonic power, practically, we use multiplepiezoelectric crystals together. The consistency of the piezoelectric crystal has greatinfluence to transducer. By using RLC equivalent circuit of piezoelec tric crystal andwith the help of measuring the admittance curve and circle of piezoelectric crystal, werealize the consistency screening. By comparing the resonant frequency on admittancecurve and the centre, radius and shape of admittance circle, we choose the transducerswhich have fine consistency and measure their dynamic response characteristics.Piezoelectric transducer’s radiation load has a big difference when it works in theair or the liquid, and its admittance radius has also an evident difference. We invent the downhole liquid-level measurement system by using these characteristics. Thissystem radiates the sine wave to transducer. When transducer down hole from air toliquid, its radiation impedance change is capture by the system. The system collectsthe voltage on transducer and the current after the transducer. And get the amplitudeof two signals with peak value detection circuit and the phase difference between twosignals with analog multiplier. The ammeters qualitatively indicate sine wave’samplitude and phase difference and this system can accurately measure cased-wellliquid level. The difference of liquid level reflects the pore pressure of formation andsituation of connection. So the liquid level instrument can be used to evaluate theeffect of ultrasonic operation.