利用非线性模型求储层孔隙度的多因素计算公式

孔隙水中的束缚水占的是无效孔隙,它与所测的地层电阻率有关。为此,在用声波时差计算孔隙度的公式中引入了Ｒｔ,得到了声波时差、电阻率和孔隙度的经验关系式。统计的相关系数高达０．９８６,平均孔隙度的绝对误差仅为０．５９％。此多因素公式在储层埋深相差很大,孔隙度变化范围也相当大的文留油田应用,大大提高了所计算的孔隙值的可信度和准确性。

A Multifactor Equation for the Computation of Reservoir Effective Porosity on the Basis of Nonlinear Model

Invalid porosity occupied by irreducible water is related with the measured formation resistivity. Therefore while deriving porosity from interval transit time Rt is introduced and an empirical relationship among interval travel time, resistivity and porosity is obtained. The statistic correlation factor is as high as 0.986 and the absolute error of the mean porosity is only 0.59%. This multifactor equation has been used in Wenliu Oilfield where the depths of oil resrvoirs are quite different and the porosity range is very large. The application result shows the confidence level and precision of the computed porosity are greatly increased.