基于差异共振声谱仪多阶共振模式的弹性模量频散测量  

Dispersion measurement using the primary and higher order resonance modes of the DARS system

作　　者：唐跟阳 董春晖[1,2] 王尚旭 曾心[1] 任保德 TANG Genyang;DONG Chunhui;WANG Shangxu;ZENG Xin;REN Baode(College of Geophysics,China University of Petroleum-Beijing,Beijing 102249,China;Ministry of Education Complex Oil and Gas Reservoir Exploration and Development Engineering Research Center,Beijing 102249,China)

机构地区：[1]中国石油大学(北京)地球物理学院,北京102249 [2]教育部复杂油气藏勘探开发工程研究中心,北京102249

出　　处：《石油科学通报》2020年第4期483-495,共13页Petroleum Science Bulletin

基　　金：国家自然科学基金(41930425,41774143)资助。

摘　　要：利用差异共振声谱系统(DARS)可测量岩石样品在~600 Hz下的压缩系数或弹性模量,该测量依靠DARS系统的一阶共振模式测量来实现,而忽略了使用更高阶共振模式可以获得的信息。本文利用DARS系统的第二、三阶共振模式测量以估算岩石样品的体积模量。使用三个参考样品代替两个参考样品,我们获得了具有更高准确度的校准参数。通过对校准参数分析,改进了测量过程,选择了具有较高敏感度的测量位置来替代传统的多点测量。在此基础上,提出了一种新的线性最小二乘反演算法,用于获得校准参数和样品弹性参数。利用这种高精度反演方法获得了7块不同孔隙度的人工砂岩样品在三个共振频率下的体积模量。这些样品的体积模量显示出从低阶共振频率(~600 Hz)到第三阶共振频率(~1800 Hz)的频散。对于具有相对低到中等渗透率的样品,频散较大,而对于具有高渗透率的样品,频散较弱。这种频散差异受渗透率控制,是由于样品孔隙中流体流动性不同,导致不同的样品落入不同的"域"。对于渗透率相对较低或中等的样品,DARS共振频率可能在频散特征频率范围内,因此频散较强。对于渗透率较高的样品,DARS共振频率处于低频范围内,体积模量几乎不随频率发生变化。根据这一结论,在地震和声波测井频率下测得的高渗透率储层岩石的弹性性质可能几乎没有差异。低渗透性的储层岩石在这些频带可能具有相当大的弹性性质差异,从而引起地震与测井获取的储层参数不匹配问题。因此,频散特征频率和强度可能是表征渗透率的指标之一。采用多阶共振频率的DARS测量方法,可以在地震—声波测井频率范围内提供直接的频散数据,对研究岩石的频散机理具有很大的潜力。频散数据还可以用来解释地震和声波频带上弹性性质的差异,为地震与测井匹配问题提供重要的参考依据。The Differential Resonance Acoustic Spectroscopy System(DARS)can be used to measure the compressibility or elastic modulus of rock samples at^600 Hz.The measurement relies on the first-order resonance mode measurement of the DARS system,while ignoring the use of higher-order resonance modes to obtain information.This article uses the second and third order resonance mode measurements of the DARS system to estimate the bulk modulus of rock samples.Using three reference samples instead of two reference samples,we have obtained calibration parameters with higher accuracy.Through the analysis of the calibration parameters,the measurement process is improved,and a measurement location with higher sensitivity is selected to replace the traditional multi-point measurement.On this basis,a new linear least squares inversion algorithm is proposed to obtain calibration parameters and sample elastic parameters.Using this high-precision inversion method,the bulk modulus of seven artificial sandstone samples with different porosities was obtained at three resonance frequencies.The bulk modulus of these samples showed dispersion from the low-order resonance frequency(~600 Hz)to the third-order resonance frequency(~1800 Hz).For samples with relatively low to medium permeability,the dispersion is large,while for samples with high permeability,the dispersion is weak.This dispersion difference is controlled by permeability,which is due to the different fluidity of the fluid in the sample pores,which causes different samples to fall into different"domains".For samples with relatively low or medium permeability,the DARS resonance frequency may be within the characteristic frequency range of the dispersion,so the dispersion is strong.For samples with higher permeability,the DARS resonance frequency is in the low frequency range,and the bulk modulus hardly changes with frequency.According to this conclusion,there may be almost no difference in the elastic properties of high permeability reservoir rocks measured at seismic and acoustic

关 键 词：DARS系统 人工砂岩 渗透率 体积模量 频散 

分 类 号：P631[天文地球—地质矿产勘探] TE311[天文地球—地质学]