Numerical Simulation Research on Reflected Wave Characteristics of Oil and Gas Well Coupling

Abstract

In order to analyse and identify the reflection morphology of the coupling reflected wave in the oil jacket annulus and to clarify the influences of different factors on the coupling reflection waveform, the COMSOL finite element analysis software is used to conduct a numerical simulation study on the above situation, and the response characteristics are obtained by calculation. In this paper, different signal sources are used to research the three-dimensional propagation characteristics of acoustic wave when it meets the coupling in the annular space. Numerical simulations are carried out for different coupling thicknesses, different coupling radii, and different oil casing annulus pressures to analyse their influences on the waveform of coupling wave. The results showed that when the polarity of the signal source was positive (negative), the coupling reflection signal was positive (negative) at first and then negative (positive). When the signal source is a positive-negative superimposed source, the first peak polarity of the coupling reflection signal is consistent with the signal source. The reflected signal is superimposed by the response generated by the positive and negative signal sources, respectively. With the increase of the coupling radius, the morphology of coupling wave remains unchanged while its reflected wave amplitude increases nonlinearly with the increase of the coupling radius; with the increase of the oil casing annulus pressure, the morphology of coupling wave does not change, but the amplitude of the reflected wave increases linearly with the increase of the pressure; as the thickness of the coupling increases, the peak-to-peak spacing of the coupling reflection wave becomes larger and the positive and negative peaks separate. The research results can provide theoretical basis and reference standards for the analysis of the characteristics of the signals received by the actual fluid level detector, the performance verification of the echo signal processing method and the correct identification of the dynamic fluid level position.