著者

大賀 光太郎 板倉 賢一 出口 剛太

出版者

石油技術協会

雑誌

石油技術協会誌 (ISSN:03709868)

巻号頁・発行日

vol.77, no.6, pp.435-437, 2012 (Released:2014-03-29)

参考文献数

1

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In our laboratory, fundamental tests on underground coal gasification (UCG) by using coal blocks were conducted for several years. Last year, a small scale field test on UCG was carried out at a part of developing area of Mikasa surface mine in Hokkaido.At the field, two bore holes were drilled, one is incline bore hole and the other is vertical bore hole. The lengths of incline bore hole and vertical bore hole were about 5m and 1.4m, respectively. The vertical bore hole was used for an oxygen injection hole and ignition hole. The incline bore hole was used for a gas production hole. Some temperature sensors were installed around the incline bore hole to measure the temperature of around the production bore hole. AE sensors were also installed around the incline bore hole to estimate the gasification zone in the coal seam. Underground Coal Gasification (UCG) demands precise evaluation of the combustion area in the coal seam. Especially, the monitoring of fracture activity in the coal seam and around rock is important not only for efficient gas production but also for estimation of subsidence and gas leakage to the surface. The test was carried out for forty hours and production gases were analyzed at every thirty minutes.Experimental results obtained showed that the combustion propagated along the linking hole inside coal seam. The temperature gradients inside the coal and the composition of production gas were changed under constant oxygen flow rate. But Average thermal value of generated gases by field test was about as much as generated gases by laboratory test.

著者

松川 瞬 板倉 賢一 早野 明 鈴木 幸司

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.11, pp.256-263, 2017-11-01 (Released:2017-11-16)

参考文献数

31

被引用文献数

1

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LIDAR (Laser Imaging Detection and Ranging) detects a rock mass surface as a point cloud, and threedimensional configurations of the rock mass can be obtained from the point cloud. In previous studies, algorithms to estimate discontinuities from a point cloud have been developed. In those algorithms, it is necessary to determine geological parameters in advance. DiAna(Discontinuity Analysis) is a Matlab tool which was developed for geostructural analysis of rock mass discontinuities. It is a semi-automatic tool. DiAna segments a point cloud into bounding boxes to estimate the surface of a rock mass. However, an expert's skills necessary to determine the appropriate size of the bounding boxes for DiAna. We developed the VBS (Variable-Box Segmentation) algorithm to determine the appropriate box size depending on the location of the point cloud and to estimate the surface of a rock mass. The VBS algorithm consists principally of three processes: large box segmentation, small box segmentation, and merging. The small boxes are merged to obtain an appropriate box size. The surface of the rock mass is estimated using the point cloud in the box. The performance of the VBS algorithms was evaluated using point clouds obtained by a geological survey. For evaluation, we estimated reference rock mass surfaces manually using the point cloud and geological sketches by geologists. Similarities among the respective reference surfaces and the surfaces estimated using the VBS algorithm were measured. Similarities among the respective reference surfaces and the surfaces estimated using the DiAna algorithm were also measured. The similarities among them were compared using standard competition ranking. The results of comparison showed that the VBS algorithm estimated planes more accurately for the reference planes than the DiAna algorithm. Therefore, the VBS algorithm determines appropriate box sizes automatically depending on the location of the point cloud and estimates the surface appropriately.

著者

児玉 淳一 立川 多久登 中 良介 濱中 晃弘 板倉 賢一 出口 剛太 福田 大祐 藤井 義明

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.134, no.7, pp.91-98, 2018-07-31 (Released:2018-07-31)

参考文献数

24

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Small-scale underground coal gasification (UCG) model tests with a linking hole were carried out using two types of specimens made of either block coal or crushed coal to clarify their characteristics of combustion and gasification. Many similar characteristics were found between both specimens in terms of temperature change and its spatial distribution as well as concentration and heating value of each gas product as long as the crushed coal specimen was sufficiently consolidated. The shape and dimension of the cavity formed in the both specimens were also similar. Texture of the both specimens was changed after the combustion and gasification. Initiation of radial cracks from the linking hole was found in the both specimens. Within the zone with the radial cracks initiation, grains in the crushed coal were bonded whereas cleats in the block coal were healed. The grain bonding and the cleavage healing can be explained by melting and expansion of coal due to temperature increase. The radial cracks are likely initiated after the grain bonding or the cleavage healing due to tensile thermal stress induced by temperature gradient in the coal specimens. It can be concluded that the characteristics of combustion and gasification of the crushed coal and the block coal are similar because both types of coals become similar in texture through combustion and gasification. These results indicate that characteristics of combustion and gasification of coal seam can be mostly estimated from a model test with artificial coal seam made of crushed coal.

著者

濵中 晃弘 蘇 発強 板倉 賢一 髙橋 一弘 佐藤 孝紀 児玉 淳一 出口 剛太

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.134, no.7, pp.81-90, 2018-07-31 (Released:2018-07-31)

参考文献数

24

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Underground coal gasification (UCG), a technique used to recover coal energy by the in-situ conversion of coal into gaseous products, enables recovery of coal energy from the potential coal resources abandoned under the ground for either technical or economic reasons. However, it might be difficult to adopt conventional UCG systems in Japan because of geological conditions that are complicated by the existence of faults and folds. Additionally, it is difficult to control the combustion/gasification area during UCG process because the process is invisible. Therefore, a co-axial UCG system that is compact, safe, and flexible to adopt is suggested with monitoring system by means of acoustic emission as an alternative UCG system. This UCG system has superiority in terms of applicability compared to the conventional one, but the recovered energy from the coal is relatively low because the gasification area in a co-axial system is limited around a well. In order to develop co-axial UCG system with high efficiency, the model UCG experiment with a large-scale simulated coal seam were conducted. It has been shown that 1) the gasification period can be extended by adopting proper oxygen inflow, 2) it is possible to control the combustion/gasification area and the product gas quality by controlling the position of oxygen inflow, 3) acoustic emission monitoring is an effective technique to evaluate the combustion/gasification area.

著者

早野 明 板倉 賢一

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ

巻号頁・発行日

vol.133, no.4, pp.76-86, 2017

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<p>Fracture mapping conducted during gallery excavation on construction projects of a large-scale underground facility is based on traditional geological techniques such as visible observations and simple measurements of fracture orientation using a clinometer. Therefore, some difficulties persist, such as securing data quality and worker safety. Three-dimensional (3D) laser scanning, which can instantly acquire point clouds representing the 3D shape of an object surface, is can be effective for resolving these difficulties. In order to confirm the applicability of the three-dimensional laser scanning to the fracture mapping on a gallery wall, this study proposes the method for obtaining attribute information from a point cloud, such as trace length and orientation, associated with the spatial distribution of fractures. In the proposed method, the two-dimensional image is generated from the point cloud to obtain the trace map. After the proposed method was applied to an approximately 50-m-long horizontal gallery excavated into the granitic rock, the reproducibility of the attribute information of fractures obtained solely from the point cloud was examined. Results show that the number of fractures extracted from the point cloud is approximately 80% of those extracted by traditional geological techniques. Although the trace length reproducibility ratio of fractures is approximately 70%, fracture orientations calculated from the point cloud compare favorably with those measured by an on-site researcher. Most fractures that were not extracted from the point cloud do not act as water-conducting fractures because they had short lengths and because they were bonded tightly. Even if the fracture data obtained from the point cloud were applied to modelling for hydrogeological analysis, the results would probably not be influenced strongly. Results of this study indicate the possibility of applying 3D laser scanning to fracture mapping.</p>

著者

早野 明 板倉 賢一

出版者

一般社団法人 資源・素材学会

雑誌

Journal of MMIJ (ISSN:18816118)

巻号頁・発行日

vol.133, no.4, pp.76-86, 2017-04-01 (Released:2017-04-29)

参考文献数

27

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Fracture mapping conducted during gallery excavation on construction projects of a large-scale underground facility is based on traditional geological techniques such as visible observations and simple measurements of fracture orientation using a clinometer. Therefore, some difficulties persist, such as securing data quality and worker safety. Three-dimensional (3D) laser scanning, which can instantly acquire point clouds representing the 3D shape of an object surface, is can be effective for resolving these difficulties. In order to confirm the applicability of the three-dimensional laser scanning to the fracture mapping on a gallery wall, this study proposes the method for obtaining attribute information from a point cloud, such as trace length and orientation, associated with the spatial distribution of fractures. In the proposed method, the two-dimensional image is generated from the point cloud to obtain the trace map. After the proposed method was applied to an approximately 50-m-long horizontal gallery excavated into the granitic rock, the reproducibility of the attribute information of fractures obtained solely from the point cloud was examined. Results show that the number of fractures extracted from the point cloud is approximately 80% of those extracted by traditional geological techniques. Although the trace length reproducibility ratio of fractures is approximately 70%, fracture orientations calculated from the point cloud compare favorably with those measured by an on-site researcher. Most fractures that were not extracted from the point cloud do not act as water-conducting fractures because they had short lengths and because they were bonded tightly. Even if the fracture data obtained from the point cloud were applied to modelling for hydrogeological analysis, the results would probably not be influenced strongly. Results of this study indicate the possibility of applying 3D laser scanning to fracture mapping.