控压钻井气-钻井液两相压力衰减影响因素分析

Analysis of influencing factors pressure attenuation characteristic in gas and mud two-phase flow during managed pressure drilling operating

考虑虚拟质量力、相间阻力、气相溶解度和滑脱速度等因素,在双流体模型基础上,建立了控压钻井气-钻井液两相流动中的压力衰减模型,借助小扰动理论和半隐式差分等数学方法,对其进行编程求解。结果表明:随着温度的增大,压力衰减系数呈线性增大趋势;随着压力的增大,压力衰减系数与压力呈反比例函数趋势;随着空隙率增大,压力衰减系数呈先增大后减小的抛物线趋势。当φg≈21%时,压力衰减系数达到最大值,当p=0.1MPa时,最大压力衰减系数可达2.32dB·m^(-1)。在低频段(w≤50Hz),压力衰减系数随频率逐渐增大;在高频段(w>500Hz),压力波的色散性基本不存在,压力衰减系数趋于恒定值。不考虑虚拟质量力的压力衰减系数最大误差达3.09dB·m^(-1),不考虑拖拽力的压力衰减系数最大误差达1.13dB·m^(-1)。

Considering the factors of virtual mass force,interphase resistance,gas phase solubility and slippage speed,a pressure attenuation model of gas drilling fluid two-phase flow in pressure controlled drilling is established based on the two fluid model.The model is solved by programming with the help of small disturbance theory and semi-implicit difference.The results show that with the increase of temperature,the attenuation coefficient of pressure increases linearly.With the increase of pressure,the attenuation coefficient of pressure and pressure show an inverse proportion function trend.With the increase of porosity,the attenuation coefficient of pressure firstly increases and then decreases.Whenφg≈21%,the attenuation coefficient of pressure reaches the maximum value.When p=0.1 MPa,the attenuation coefficient of pressure reaches 2.32 d B·m^(-1)at low frequency.The pressure attenuation coefficient increases with the frequency when the frequency is less than 50 Hz.In the high frequency when the frequency is more than 500 Hz,the dispersion of the pressure wave is almost nonexistent,and the pressure attenuation coefficient tends to be a constant.The maximum error of the pressure attenuation coefficient without considering the virtual mass force is 3.09 dB·m^(-1),and the maximum error of the pressure attenuation coefficient without considering the drag force is 1.13 dB·m^(-1).