Efficient detection of methane seepage using a vehicle-mounted cavity ring-down spectroscopy analyzer

Niwa, Masakazu; Shimo, Michito*; Shimada, Koji; Goto, Akira

JAEA-Research 2022-004, 38 Pages, 2022/06

JAEA-Research-2022-004.pdf:2.86MB
JAEA-Research-2022-004-appendix(CD-ROM).zip:0.41MB

Methane (CH) seepage to the surface in the early stage of hydrocarbon exploration has attracted increasing attention. Also, detection of CH-rich fluid emission can be applied to reconnaissance surveys for safety management in geological disposal of radioactive waste because high-temperature fluids that come from slab dehydration along a subduction zone are often rich in CH. These fluids likely migrate along faults and fractures. In this study, we employed a portable analyzer that used a wavelength-scanned cavity ring-down spectroscopy (CRDS) with high accuracy (in ppb levels) and short measurement intervals (1 s). An on-vehicle measurement that employed the CRDS system was performed in the Hongu area in southeast Kii Peninsula, Japan, which included CH-bearing hot springs (Kawayu and Yunomine). The measurement near the hot springs detected a clear CH anomaly (2 ppm) that exceeded the background concentration. The estimation of CH diffusion in air based on the Gaussian plume model corresponded to the result of the on-vehicle measurement. This study confirmed that the method using the vehicle-mounted CRDS analyzer can help in quickly and easily identifying CH-bearing fluid emissions at the surface. Additionally, directions for use of the analyzer were summarized in this report.

Infrared images of outcrops around the Kawayu hot springs, Hongucho, Tanabe City, Wakayama Prefecture

Shimada, Koji; Goto, Akira; Niwa, Masakazu; Shimo, Michito*

Chishitsugaku Zasshi, 127(10), p.I - II, 2021/10

AA2021-0095.pdf:1.35MB

https://doi.org/10.5575/geosoc.2021.0021

Continuous leaking point of high-temperature fluid (liquid/gas) from underground can be easily grasped by infrared images. We show images confirmed by a FLIR C5 camera that can simultaneously obtain an infrared image and a visible light image at the outcrops of Kawayu Onsen that naturally spring along the river. Outcrops and river surface temperature rise due to hot springs that leaking from riverbanks and riverbeds, rock temperature rise around cracks where gas containing high-concentration methane leaks with hot springs, abandoned fluid pathway due to construction of the bank and damming river for hot spring river bath in winter can be confirmed at a glance. Infrared images may be useful for quick identification of hot fluid leaking points from underground.

Estimation of gas migration pathways around faults based on the distribution of atmospheric methane near ground surface

Shimo, Michito*; Niwa, Masakazu; Miyakawa, Kazuya; Amano, Kenji; Tonokura, Kenichi*; Tokunaga, Tomochika*

Fukada Chishitsu Kenkyujo Nempo, (22), p.119 - 137, 2021/00

no abstracts in English

Study on hydrogeology on Mizunami Underground Research Laboratory Project; Hydrogeological modeling and groundwater flow simulation based on data of hydraulic and geochemical impacts during the construction of the MIU facilities (FY 2008)

Shimo, Michito*; Kumamoto, So*; Kosaka, Hiroshi; Onoe, Hironori; Saegusa, Hiromitsu; Mizuno, Takashi; Oyama, Takuya

JAEA-Research 2012-004, 126 Pages, 2012/04

JAEA-Research-2012-004.pdf:14.3MB

One of the goals of Mizunami Underground Research Laboratory (MIU) Project is to develop technical basis for investigation, analysis and evaluation technologies for understanding deep underground geological environment in various scales. Understanding groundwater flow system is one of the important issues in the project, and to achieve this purpose, technologies for a hydrogeological model and the groundwater flow simulation technique, have to be established. In this study, hydrogeological modeling and groundwater flow simulations have been carried out in order to predict hydraulic and geochemical impacts around the MIU Construction Site and inflow rate into the MIU facilities. As a result of this study, the significant hydrogeological structures could be estimated. The inflow rate into the MIU facilities and hydraulic and geochemical impacts with the MIU facilities construction could be predicted. The effect of pre-grouting to the MIU facilities could be also confirmed.

Study on flow and mass transport through fractured sedimentary rocks (Joint research)

Shimo, Michito*; Kumamoto, So*; Ito, Akira*; Karasaki, Kenji*; Sawada, Atsushi; Oda, Yoshihiro; Sato, Hisashi

JAEA-Research 2010-040, 57 Pages, 2010/11

JAEA-Research-2010-040.pdf:5.12MB

In safety analysis of geological disposal of the high-level nuclear waste, it is important to evaluate appropriately the mass transport characteristics of the bedrock as the natural barrier. Especially, it has been found that the porosity of the rock matrix is high and fractured zones are developing and therefore the mass transport characteristics will be the mixture of those for porous media and the fractured media. In this work, we conducted, (1) a study on the method to mine out the rock block sample of tens of-centimeter to maximum 1 m scale, (2) a study on a method of the tracer test using a rock block sample and a series of scoping analysis. We also examined the uncertainty associated the hydrogeological model using a method combining a forward and inverse analysis, based on the various type of data sets obtained at Horonobe site, such as the temperature distribution and hydraulic head and salinity distribution.

Uncertainty reduction of hydrologic models using data from surface-based investigation

Karasaki, Kenji*; Ito, Kazumasa*; Wu, Y.*; Shimo, Michito*; Sawada, Atsushi; Maekawa, Keisuke; Hatanaka, Koichiro

Proceedings of TOUGH Symposium 2009 (Internet), 9 Pages, 2009/09

Hydrogeological modelling with inflow volume and pressure response during groundwater recovery and discharge in shaft

Kumamoto, So*; Shimo, Michito*; Saegusa, Hiromitsu; Oyama, Takuya

Dai-38-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM), p.281 - 286, 2009/01

The Mizunami Underground Research Laboratory is being constructed by Japan Atomic Energy Agency in the Cretaceous Toki Granite in the Tono area, Central Japan. During construction, the information needed for testing and revising the hydrogeological model has been obtained. During shaft excavation, pumping of groundwater from the shaft has to be halted and the water level in shaft was recovered for the improvement of facility for treatment of discharged groundwater. This period was divided into three major phases, such as excavation, recovery and discharging phases, and hydraulic behavior in the phases was considered as a large-scale pumping test. In this study, model testing and calibration using the data of inflow volume and hydraulic behavior observed in these three phases have been carried out.

Hydrogeological characterization for estimation of hydraulic responses due to construction of the Mizunami Underground Research Laboratory

Saegusa, Hiromitsu; Shimo, Michito*; Kumamoto, So*; Onoe, Hironori; Takeuchi, Ryuji; Takeuchi, Shinji; Oyama, Takuya

Proceedings of 36th International Association of Hydrogeologists Congress 2008 (IAH 2008) (CD-ROM), 10 Pages, 2008/10

One of the main goals of the Mizunami Underground Research Laboratory project is to establish comprehensive techniques for investigation, analysis, and assessment of the deep geological environment. Hydrogeological investigations using a stepwise manner have been carried out to obtain information on important properties. Hydrogeological modeling and groundwater flow simulations, which is for estimations of volume of inflow into underground tunnels and impact of construction of underground facilities on water table and hydraulic pressure, have been carried out by synthesizing these investigation results. From the study, the uncertainty of the hydrogeological model was evaluated and the main issues for further investigations were identified. Also, hydrogeological modeling and groundwater flow simulation using the data of hydraulic responses due to shaft sinking have been carried out in order to test/revise the models constructed in Phase I. These results are introduced in this paper.

Study on flow and mass transport through fractured soft sedimentary rocks (Contract research)

Shimo, Michito*; Kumamoto, So*; Maekawa, Keisuke

JAEA-Research 2007-016, 141 Pages, 2007/03

JAEA-Research-2007-016.pdf:20.36MB

It is important for safety assessment of HLW geological disposal to evaluate groundwater flow and mass transport in deep underground accurately. Though it is considered that the mass transport in sedimentary rock occurs in pores between grains mainly, fractures of sedimentary rock can be main paths. The objective of this study is to establish a conceptual model for flow and mass transport in fractured soft sedimentary rock. In previous study, a series of laboratory hydraulic and tracer tests and numerical analyses were carried out using sedimentary rock specimens obtained from Koetoi and Wakkanai formation. Single natural fractured cores and rock block specimen were used for the tests and analyses. The results indicated that the matrix diffusion played an important role for mass transport in the fractured soft sedimentary rocks. In this study, the following two tasks were carried out: (1) laboratory hydraulic and tracer experiments of rock cores of koetoi and Wakkanai formation obtained at HDB-9, HDB-10 and HDB-11 boreholes and a rock block specimen, Wakkanai formation, obtained at an outcrop in the Horonobe area, (2) a numerical study on the conceptual model of flow and mass transport through fractured soft sedimentary rocks. Non-sorbing tracer experiments using naturally fractured cores and rock block specimens were carried out. Potassium iodide was used as a tracer. The obtained breakthrough curves were interpreted and fitted by using a numerical simulator, and mass transport parameters, such as longitudinal dispersivity, matrix diffusion coefficient, transport aperture, were obtained. Mass transport simulations using a fracture network model, a continuum model and a double porosity model were performed to study the applicability of continuum model and double porosity model for transport in fractured sedimentary rock.

Calibration of groundwater flow model with result of cross-hole hydraulic test

Kumamoto, So*; Shimo, Michito*; Saegusa, Hiromitsu; Onoe, Hironori

Dai-36-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM), p.287 - 292, 2007/01

http://library.jsce.or.jp/jsce/open/00019/2007/36-0287.pdf

no abstracts in English