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Shimo, Michito*; Yokoi, Satoru*; Miyakawa, Kazuya; Niwa, Masakazu; Matsuoka, Toshifumi*; Tokunaga, Tomochika*
no journal, ,
In this presentation, we report several preliminary studies to detect methane seepage using a portable gas analyzer by cavity ringdown spectroscopy.
Otani, Tomoyuki*; Yokoi, Kosuke*; Okazaki, Kazunari*; Nishimura, Yuki*; Kojima, Satoru*; Kuboshima, Koji*; Sasao, Eiji
no journal, ,
The orientation of microcracks was measured using the MIU-3 core penetrating the Tsukiyoshi fault to clarify the relation of the microcrack distribution near the fault. Attitude of microcracks in quartz grains in granite are measured under the optical microscope with the universal stage using three perpendicular thin sections. The healed microcracks was probably formed prior to the sealed microcracks. Both healed and sealed microcracks with moderate dip appears near the fault. The distribution of microcracks with moderate dip shows that the preferred orientation of microcracks near the fault is different from that far from the fault. The distribution of the sealed microcracks with moderate dip is narrower than that of the healed microcracks. This shows that the healed microcracks with moderate dip was developed in the intact granite at the earlier stage of the faulting history, and the sealed microcracks was in the weak fault zone which has repeated rupturing and healing at the later.
Yokoi, Satoru*; Shimo, Michito*; Miyakawa, Kazuya; Niwa, Masakazu; Matsuoka, Toshifumi*; Tokunaga, Tomochika*
no journal, ,
In this presentation, we report methane gas seepages along an anticlinal axis in the Horonobe area, northern Hokkaido, and discuss migration paths from an underground reservoir.
Shimo, Michito*; Niwa, Masakazu; Yokoi, Satoru*; Yagi, Hiroshi*; Tokunaga, Tomochika*
no journal, ,
This study focuses on the role of faults as pathways for gas migration from the deep subsurface and aims to detect trace gas seepage along these faults. For this purpose, methane concentrations near the surface across the Aosawa Fault, Yamagata Prefecture, were measured using Cavity Ring-Down Spectroscopy (CRDS). Notable increases in methane concentration were observed at anticipated fault locations on two transects across the Aosawa Fault. The measurement results suggest that the Aosawa Fault functions as a pathway for gas migration connected to deep underground methane sources, offering new perspectives on fault structures and their relation to the petroleum system in the study area.
Yokoi, Satoru*; Shimo, Michito*; Niwa, Masakazu; Matsuoka, Toshifumi*; Tokunaga, Tomochika*
no journal, ,
In this study, applicability of gas concentration mapping using an on-board portable gas analyzer by cavity ring-down spectroscopy (CRDS) was shown in sedimentary basins where large fault zones could act as migration paths.