声波测井的探测深度及侵蚀作用对声波时差测量的影响

The radial sounding distance of acoustic log and the influence of mud-fiuid etching upon acoustic interval transit time

本文根据泥浆对岩层的侵蚀特点,从理论上导出了声波测井的探测深度计算公式及岩层受泥浆侵蚀后的声波时差误差与侵蚀带厚度的关系,详细阐述了岩层受泥浆侵蚀后对声波时差测量的影响情况;另外,还研究了侵蚀带厚度随时间的变化规律及求取侵蚀带厚度的方法。这些研究成果是基于侵蚀带速度径向(横向)变化较小的条件下实现的。文中给出了 BS 井三次声波测井资料的分析实例。对今后声波测井如何选择合适源距的测井仪器及对仪器的改进具有指导意义。

In the light of the property of mud-fluid etching in rock forma- tion,the formula for calculating radial sounding distance of acoustic log is derived,and the relation between error in acoustic interval transit time and etching belt thickness is analysed.It is detailed how the acoustic interval transit time is influenced by mud-fluid etching. Furthermore,the paper also describes the variation of etching belt thickness with time and the method for calculating etching belt thick- ness.Above results were obtained on the basis of the fact that acous- tic velocity in the etching belt shows small lateral variation. The example is given of analysing the acoustic log data which were collected from BS well in three times respectively.This is sig- nificant to both selection of acoustic log device with proper trans- mitter-receiver distance and device improvement.