Application of Multiscale X-CT Imaging Digital Core Technique on Observing Micro-pore Structure of Carbonate Reservoirs

doi:10.19657/j.geoscience.1000-8527.2019.03.17

Abstract

Abstract:

In this paper, we analyzed two types of core samples from porous carbonate reservoir via X-CT imaging to better constrain their microscopic pore structural features. The two sample types are namely the double porosity medium with fracture development and single porosity medium with no fractures. Three dimensional (3D) digital cores of different levels are established via the multi-scale X-CT scanning imaging technology, using the maximal ball algorithm and the method for pore and throat size correction, and consequently the digital cores nanoscale pore network model in carbonate reservoirs are extracted and established. Finally, the 3D pore network model is used to simulate the reservoir physical parameters, mercury injection curves and the pore and throat distribution curves, and the results are compared with those generated by the conventional high-pressure mercury injection method. The results show that the porosity and permeability parameters obtained by using the digital core technology are smaller than the actual measurements. The simulated mercury injection curves and pore throat distribution curves are in good agreement with those obtained by the laboratory mercury intrusion experiment, demonstrating that this technique is reliable. Digital core technology has clear strengths in directly and quantitatively described the micro-pore structure of carbonate reservoirs.

Key words: X-CT scanning, carbonate rock, micro-pore structure, multiscale fusion

CLC Number:

TE122

SHENG Jun, YANG Xiaojing, LI Gang, XU Li, LI Yanan, WANG Jingru, ZHANG Caiyan, CUI Haidong. Application of Multiscale X-CT Imaging Digital Core Technique on Observing Micro-pore Structure of Carbonate Reservoirs[J]. Geoscience, 2019, 33(03): 653-661.

Figures/Tables 10

Fig.1 Extraction process of pore network model using maximal ball algorithm

Fig.2 Schematic diagram of division and correction of pore and throat

Fig.3 Photos of the selected core samples from the carbonate reservoirs for the experiment

Fig.4 Whole-core CT scanned image and 3D profiles

Fig.5 Vertical cross-section of sample No.1

Fig.6 Fine CT scanned map for parts of sample No.2

Fig.7 BSE image of sample No.2

Fig.8 3D digital rock model and extracted 3D pore space after segmentation by micron-scale CT scanning

Fig.9 Three-dimensional digital model of rock, the pore space and 3D pore network after micro-/nano-scale fusion

Fig.10 Comparison between simulated mercury injection curve, pore throat radius distribution curve with the measured results

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