Transport properties for heterogeneous carbonate rocks [thesis]

Ahmad Dehghan Khalili
This thesis describes a methodology to upscale permeability and formation factor in the context of digital core analysis. A combination of high-resolution and low resolution Xray-CT images is used to calculate permeability and formation factor at the conventional core plug scale for highly heterogeneous carbonate rock. Carbonates exhibit heterogeneity at several length scales having significant effects on the physical characteristics of the medium. While measuring transport properties
more » ... ally on a standard core plug provides only a single measurement, Xray-CT methods allow the direct imaging of the structure, provide an assessment of uncertainty through rock-typing methods, sub-sampling, and successive transport property calculations, and are the basis for sensitivity studies. However, for heterogeneous rock comparisons between experiment and numerical simulation on the basis of Xray-CT images can only be carried out at the same field of view. Imaging at the coarse scale is not sufficient, because at the pore scale, high physical property contrasts exist and the contribution of both macro- and micro-features to effective transport properties must be addressed carefully. Therefore, a combination of high-resolution images for accurate derivation of transport properties, geostatistical property distribution techniques, and robust upscaling techniques is used to calculate effective transport properties of the whole core. We use helical micro-CT scanning and scan high resolution image of sample with length up to 19mm, to solve Laplace equation at this resolution and establish correlations between permeability, formation factor and porosity. Three-dimensional tomogramto- tomogram registration is used in order to reconcile images with different resolutions and calibrate the porosity map of the low resolution image with wider field of view (FOV). We investigate the representative elementary volume (REV) and evaluate the correlation-length of each property. The effect of structural heterogeneity on the effective tr [...]
doi:10.26190/unsworks/16410 fatcat:dt67z7fhhvcxfh64dom5urdakq