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由常规声波测井仪测得的纵波信息要受地层水和/或泥浆滤液矿化度、溶解气、井眼温度、地层温度、孔隙压力、低饱和自由生物气及烃类等因素的影响。关于这些因素的影响程度,声波测井的用户们还不能很好地估计。这些因素对声波时差测量值有重要的影响,从而对利用声波测井资料估测孔隙度产生显著影响。此外,这些因素对纵波传播时间与地震速度或幅度的关系也有明显的影响。文中实例证实了在非固结砂岩中这些因素对测量时差的影响可达到10μs或10μs以上。 Wyllie时间平均方程或Raymer-Hunt传播时间方程一类的常规声波方程,对揭示这些环境因素可能影响常规声波测井信息几乎没有帮助。研究这些影响因素的实验结果表明:Gassmann方程可用来描述这些环境因素对砂岩储集层的影响。文中展示的实验结果提供了评估这些因素对测量时差(Δt)影响的程度。研究得到的结果为消除这些因素对声波测井的影响提供了一种校正方法。这样就可以利用声波测井资料更精确地求取孔隙度和流体含量,同时也能改善声波测量时差与地震速度和校验炮速度的关系。
P-wave information measured by conventional sonic logging tools is affected by such factors as formation water and / or mud filtrate salinity, dissolved gas, borehole temperature, formation temperature, pore pressure, low saturation free biogas and hydrocarbons. The impact of these factors, sonic logging users are still not well estimated. These factors have a significant impact on sonic time-lapse measurements, which can have a significant impact on the estimation of porosity using sonic log data. In addition, these factors also have a significant impact on the relationship between the propagation time of the P-wave and the velocity or amplitude of the earthquake. The examples in this paper confirm that the influence of these factors on the measurement of time lag in unconsolidated sandstones can reach 10μs or more. The conventional acoustic wave equations, such as the Wyllie time averaging equation or the Raymer-Hunt propagation time equation, provide little help in revealing that these environmental factors may affect conventional sonic log information. The experimental results of studying these influencing factors show that the Gassmann equation can be used to describe the impact of these environmental factors on sandstone reservoirs. The experimental results presented in the paper provide the degree to which these factors can affect the measurement of the time difference (Δt). The results of the study provide a method of correction for eliminating the influence of these factors on acoustic logging. This allows for the more accurate determination of porosity and fluid content using sonic log data, as well as improving the relationship between sonic time differences and seismic velocities and calibrator velocities.