Coal Bed Characterization Studies with X-ray Computerized Tomography (CT) and Micro-CT Techniques

ABSTRACT

Much of the focus of CBM reservoir assessment in Canada is based on understanding cleats and natural fractures, both in outcrop and in core taken from well bores. Coal characterization studies using imaging devices are presented. X-ray computerized tomography (CT) and micro CT are used on coal samples to provide a better understanding of fracture morphology and apertures. Images are collected in samples of approximately 10 cm in diameter with resolution of (0.4 mm) 2 using X-ray CT, and samples of 1 cm in diameter with resolution of (5_m) 2 using micro CT. Visualization at both resolutions allows for discussion and comparison of structural characteristics at both scales. X-ray CT images are processed to obtain density “logs” and maps under different overburden pressures. The pore space contained helium, and, in one set of scans, argon. Bulk densities increase with increasing overburden pressure. Fracture patterns in both cores were reconstructed from the images using a fracture identification algorithm. Manipulation of the density maps can also provide local strains as a function of increasing overburden pressure.

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