Quantitative Analysis of Microscopic Scales of Heterogeneities in Reservoir Rocks from Image Analysis Technique

摘要

Quantitative investigation into textural heterogeneities of six sandstones and two limestones at the microscopic scales was carried out by analyzing digital images captured from large format thin sections of the rock samples. The images were analyzed to obtain textural (porosity) profiles of the rock samples using the image analysis technique and processed to determine the periodicities of heterogeneity within the rocks using the Fast Fourier Transforms (FFT). The amplitude spectra of the rock porosities were compared with spectra of attenuation losses of the samples measured at the resonant bar frequency to find a correlation between attenuation losses and the microscopic heterogeneity at approximately 1mm which is the characteristic squirt length suggested by Dvorkin et al (1995, 2004). The results show a weak correlation between attenuation losses and the characteristic squirt – flow length at 1mm wavelength. The technique proves to be a useful tool in determining the scale-dependent heterogeneity in reservoir rocks and could be applied in reservoir characterisation and engineering.