控压钻井中三相流体压力波速传播特性

考虑虚拟质量力、相间阻力、气相溶解度及滑脱速度等因素,在双流体模型基础上,建立了控压钻井中油-气-钻井液三相流体压力波速模型. 将溢流气体视为气相,将溢流油相及钻井液相视为液相,液相弹性模量及密度等参数为油相及钻井液相中各参数的加权和,利用半隐式差分及小扰动理论等数学方法,借助计算机编程对其求解. 结果表明,当井底气侵量从0.36m3/h 增至3.6m3/h,波速减小峰值为498.59m/s,而相同的油侵增加量,波速呈缓慢减小趋势,波速减小峰值为19.21m/s;当回压从0.1MPa 增至9.0MPa,波速呈增大趋势,波速增大峰值为233.15m/s;不考虑虚拟质量力,在低频段引起的波速误差呈增大趋势,在高频段引起的波速误差峰值稳定于10.03%. 

RESEARCH ON PRESSURE WAVE PROPAGATION CHARACTERISTICS IN THREE-PHASE FLOW DURING MANAGED PRESSURE DRILLING

In this paper, considering the virtual mass force, resistance, gas solubility and gas slip velocity etc., a model for predicting transient pressure wave velocity in oil-gas-water is established on the basis of the two-fluid equations. The influx gas is regarded as gas phase, and the influx oil is regarded as liquid phase. Parameters of liquid phase, such as elastic modulus and density, are defined as the weighted sum of the parameters of gas phase and drilling fluid. With the help of computer programming, the model is solved by the small disturbance theory and semi-implicit finite difference mathematical method. Results show that the pressure wave velocity is decreased by as much as 498.59m/s when the gas influx rate at the bottomhole increases form 0.36m3/h to 3.6m3/h. Meanwhile, the pressure wave velocity shows a slowly decreasing tendency at the same oil influx rate increase, decreasing by 19.21m/s. As the back pressure increases from 0.1MPa to 9.0MPa, the pressure wave velocity has an increasing tendency at a maximum increase of 233.15m/s. At low frequencies range, an increasing calculation error of pressure wave velocity can be observed with the increases of angular frequency by neglecting virtual mass force. At high frequencies range, the calculation error keeps constant at 10.03% when the influence of virtual mass force is neglected.