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目前我国大部分油田已进入开发中后期 ,80 %以上的油井依靠机械抽油生产。在有杆泵抽油生产条件下 ,流体的速度和压力都随时间变化 ,处于非稳定流动状态。然而长期以来 ,国内外一直采用稳定流动模型对测试资料进行分析 ,往往导致错误的结果。分析流体非稳定流动的机理 ,发现其特征是 :活塞上冲程的流量随时间逐渐增大 ,其变化趋势近似于正弦曲线的π/2周期 ;活塞下冲程的流量随时间逐渐减小 ,其变化趋势近似于指数曲线。由于井内流体波动变化的波长大于流道直径 ,引用一维连续波方程作为测量分析模型。分析的关键在于如何估计扰动速度 ,可以根据实际生产工况和测试响应特征 ,确定分析模型中的有关参数 ,进而准确计算流体的总平均速度和体积流量。图 1参 2
At present, most of the oilfields in China have entered the middle and late stages of development. More than 80% of oil wells rely on mechanical pumping. In sucker rod pumping oil production conditions, the fluid velocity and pressure changes over time, in a state of unsteady flow. However, for a long time, the steady flow model at home and abroad has been used to analyze the test data, often leading to wrong results. The mechanism of fluid unsteady flow was analyzed and it was found that the flow rate of piston up stroke gradually increased with time, and the trend was similar to the π / 2 cycle of sinusoidal curve. The flow of piston down stroke decreased with time, and the change The trend approximates the exponential curve. Because the wavelength of the fluid fluctuation in the well is larger than the diameter of the flow channel, a one-dimensional continuous wave equation is used as a measurement and analysis model. The key point of the analysis is how to estimate the turbulence velocity. The relevant parameters in the analytical model can be determined according to the actual production conditions and the test response characteristics, and then the total average velocity and volume flow of the fluid can be accurately calculated. Figure 1 reference 2