利用密度迭代法计算气井的井底流压

Calculation of bottom-hole flowing pressure of gas well using density iteration method

依据井筒压力与气体密度和湿度之间的函数关系,采用密度迭代法,以井口套压为起点自上而下迭代至井底,计算出井底流压。选择有实际关井测压数据的8口井,将不考虑天然气湿度条件下(干气)用密度迭代法计算的井底流压与实际测压值对比,平均相对误差仅为4.89%;考虑湿度对井底流压的影响,计算了不同气体湿度下的井底流压,与实际测压值之间最大误差为1.369 1%。将用密度迭代法、经验公式及RTA法计算的井底流压与实际测压值进行比较,发现前者的误差最小,而且使用该方法能在不影响气井正常生产的情况下精确计算气井的井底流压,适用于气井整个生产历程中的井底流压计算。

According to the functional relationship between borehole pressure of gas well and the density and moisture of gas in the borehole,the bottom-hole flowing pressure is calculated by density iterating from the well head to the well bottom. The bottom-hole flowing pressure of 8 gas wells which are of measured bottom-hole flowing pressure data is calculated under no considering the moisture of borehole gas,and the calculated data are compared with the measured data. It is shown that the average relative error of the calculated bottom-hole flowing pressure of 8 wells is only 4. 89%. The maximum error between the calculated bottom-hole flowing pressure under different gas moisture and the measured bottom-hole flowing pressure is 1. 369 1%. The calculated bottom-hole flowing pressure using the density iteration method,empirical formula and RTA separately is compared with the measured data,and it is shown that the calculation error of the density iteration method is the least. In addition,calculating bottom-hole flowing pressure using the density iteration method does not influence the normal production of gas well,the method is suitable to the calculation of bottom-hole flowing pressure in the whole production process of gas wells.