X-Ray CT (Computed Tomography) was developed as a non-distractive inspection tool, and the system spread firstly in the medical field. Since the advantage as a non-distractive inspection tool is recognized in the engineering field, X-ray CT system has been applied in the various kinds of research field including rock engineering. In the case of rock engineering, rocks inevitably contain a lot of hetelogeneity, such as cracks, pores and different kinds of grains. Therefore, the understanding of these characteristics is the first step to develop the research, and X-ray CT has been expected as one of the most useful and effective tools. In this paper, fundamental knowledge of X-ray CT system, types of X-ray CT scanners and their applicability to the rock engineering were introduced. Here, the subjects were focused on the geomaterials such as rocks, stones and closely related materials, and histories of the X-ray CT applications for each research topic, way of analysis and merit/demerit of X-ray CT applications were introduced. The prospective of X-ray CT and its application were also discussed.
Microbial methanogenesis occurs in diverse subsurface environments. Even though the process of methanogenesis in subsurface environments plays an important role in the global-scale carbon cycle and may aid more effective utilization of biogenic methane as an energy resource, the process is not yet well understood. In Northern Hokkaido, we have experimentally proved that the methane dissolved in groundwater was biogenic. In addition, we were successful in isolating and culturing methanogens from the coal and diatomaceous shale formations of Northern Hokkaido. In particular, the dominant methanogens isolated from the diatomaceous shale formation will help in understanding some of the processes of methanogenesis in subsurface environments. Conversion of source rocks into bio-methane with the help of microorganisms is expected to be of high profitability. This process will also enable the production of the desired resource by completely avoiding the mining process, thereby allowing the utilization of an unused resource in Japan. This paper primarily reviews the bio-methane production potential in North Hokkaido based on the abovementioned facts. Subsequently, a new method, subsurface cultivation and gasification, has been proposed for the production of biogenic methane gas in the subsurface environment. Our approach employs hydrogen peroxide for the chemical decomposition of the organic matter into usable substrates for methanogens. Finally, we intend to address a few issues of bio-methane production engineering in subsurface environment.