The Research Of The Characteristics Of Ultrasonic Wave Propagation In The Underground Mixed Media

In recent years, the country’s demand for oil is increasing, which means thatthe large-scale underground mining work in China’s Daqing oilfield also becomesincreasingly heavy. However, the formation slippage and other factors, oftenresulting in underground transport crude oil casing dislocation, resulting in the wellcan not continue to work and affecting production. So repairing the sleeve has beena hot research direction. The lower casing broken around1000meters underground,common methods can not detect its orientation. In this paper, because of anti-interference, low cost, the ultrasound equipment is used for testing, and the distanceneeded the size of the echo amplitude and ideally acoustic velocity, and the echoamplitude is the bigger the better, that is, the smaller the better amplitudeattenuation coefficient, this is conducive to an accurate reading, but also tofacilitate the speed of sound and accurate data processing. But the soundpropagation velocity, amplitude attenuation coefficient and the propagation mediumcharacteristics related, so you need to make a theoretical prediction model targetedthe speed of sound, amplitude attenuation for underground mixed media.Currently traditional mixed media decay model does not consider the effect ofchanges in the particle size of the suspended particles, and the environment isapplicable to normal temperature and pressure, However, changes between thetemperature and pressure on the ground and the underground temperature andpressure may have an impact on the attenuation, so the traditional attenuationprediction model does not apply to underground mixed media. So considered theenvironmental impact of temperature, pressure, particle size of suspended oildroplets, this paper analyzed the ultrasonic propagation characteristics inunderground mixed media and made verified experiments.Analyzing the physical properties of the underground mixed media, includesthe media’s physical form. Analyzing the influence on its physical form, which iscaused by the change from normal to underground, solving associated physicalparameters, using instruments to observe and measure the underground mixedmedia, simulating the influence on the uniformity of the sound field caused by theacoustic frequency and amplitude; according to the actual physical state of theunderground mixed media, analyzing sonic characteristics in order to establish aspeed model of sound.The theoretical analysis of the acoustic attenuation characteristics of theunderground mixed media, includes the crude oil droplets viscous decay, heat wave attenuation and multiple scattering attenuation, in addition to the attenuation causedby CH4bubbles in the mixed medium. Considering the impact of the hightemperature and pressure of the underground environment, the diameter changes ofthe suspended oil droplets and CH4bubbles, the change of the acoustic frequency,this paper established a mathematical model of the attenuation, and did acomparative analysis targeted with the traditional model.A set of experiments system was designed to simulate the environment of hightemperature and pressure underground, and conducted experiments, recording andanalyzing the speed of sound and the amplitude decay of echo signal at differentpressures, temperatures, oil droplets, concentration and other conditions, andcompared with the calculate values of the new mathematical model, the resultsshow: the new model data and measured values less than5%, curve fitting better,the same trend.