Influence of Sensitive Parameters on Pressure Wave Velocity of Gas Drilling Fluid

In this paper, the authors have simulated pressure wave propagation in a closed system, considering the virtual mass force on the interphase border, the viscous shear force, the slippage velocity, and the narrow drag conditions. Based on the gas-liquid momentum conservation and mass conservation principles, the two-fluid model is established. To solve the model, considering the small disturbance principle and ignoring the second-order items, the basic equations are converted into vector form, and the final equation of velocity is obtained. The model is solved by the software program. The results show that with increase in porosity and decrease in the system pressure, temperature, and density of the liquid phase, the pressure wave propagation velocity decreases. With decrease in the low-frequency angular frequency, the slip velocity, and other factors that can slow down the gas-liquid exchange rate, the pressure wave velocity also decreases. With increase in the incompressibility of the gas-drilling fluid system and decrease in the interphase exchange time, the pressure wave propagation velocity increases. When the pressure wave frequency is low, the wave velocity is restricted mainly by the mechanical characteristics of the phase and the mechanism of thermodynamic balance.