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Kobayashi S.,Shimizu Corporation | Soya M.,Shimizu Corporation | Takeuchi N.,Shimizu Corporation | Onishi M.,Shimizu Corporation | And 3 more authors.
ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014 | Year: 2014

The world's largest underground storage facility for Liquefied Petroleum Gas (LPG) was constructed in Cretaceous granitic rock in the Inland Sea near Kurashiki in western Japan. This facility is being operated using a water curtain system in order to control the flow of groundwater and pore pressure, thereby ensuring long-term safe LPG storage. Grouting was also conducted during the excavation of rock caverns so as to control the hydraulic conductivity of the rock mass appropriately. Pre-excavation grouting was conducted under high grouting pressure (about 4.2 MPa) in order to control the hydraulic conductivity below 0.35 Lugeon. Also post-excavation grouting was carried out if the inflow exceeded the requirement. After the excavation of the grouted areas, the effects of grouting were checked by measuring the inflow rate and the pore pressure around the storage caverns. If needed, geological survey, analysis of measurement data, and analysis of grouting data were carried out and grouting designs were rationally revised step by step in terms of grouting equipment, grouting materials, grouting patterns, and criteria of additional holes. The main grouting material was super-fine cement for the whole of the cavern. However, a micro-fractured zone (mf-zone) was encountered, where improvement effect with cement grout was limited despite many changes in grouting design made. In this zone, colloidal silica grout (CSG) was used as a supplement, after confirming its suitability for long-term sealing at the Kurashiki Base. Because of little precedent of using CSG for rock grouting in Japan, specifications of CSG grouting were reviewed and adjusted based on information-based technique. The results of pre-grouting with CSG in the cavern indicates that the mf-zone where improvement of sealing effect was not sufficient when using cement grouting, has been improved using CSG. As a result, the inflow to the LPG caverns and the groundwater pressure around the caverns after the completion of construction were within the scope of the prediction. © 2014 by Japanese Committee for Rock Mechanics.

Oshika J.,Japan National Oil Corporation | Arakawa Y.,University of Tsukuba | Endo D.,University of Tsukuba | Shinmura T.,Kumamoto Gakuen University | Mori Y.,Kitakyushu Museum of Natural History and Human History
Journal of Volcanology and Geothermal Research | Year: 2014

Petrological and geochemical investigations were performed on the uniquely distributed Nanzaki basanite (0.43Ma) in the northern part of the Izu-Bonin volcanic arc, Japan, to clarify its original magma chemistry, and to constrain the source mantle and formation process of the magma. The Nanzaki basanite (monogenetic volcano) is mainly composed of nepheline-bearing basanite lava and scoria. The mineral chemistries are characterized by high forsterite (Fo) contents of olivines, high Mg# (=Mg/(Mg+Fe)) values of clinopyroxenes, and low Cr# (=Cr/(Cr+Al)) values of spinels. Whole-rock major element contents have narrow variation ranges as follows: SiO2 (41.5-44.1%), MgO (10.2-13.1%), CaO (11.9-13.3%), and K2O (0.4-1.9%). Combined with these mineral and whole rock chemistries, the low FeO*/MgO (0.81-1.09) values, high Ni and Cr contents, and narrowly distributed rare earth element (REE) patterns of the Nanzaki basanite represent the primary (undifferentiated) chemical features of the magmas. The incompatible trace element characteristics, especially the high Sr, Ba, and REE contents and low K, Rb, Zr, Hf, and Ti contents, suggest that the basanite magmas were generated from an enriched mantle that was affected by metasomatism with carbonatite magma (or carbonate-melt). In addition, the slight enrichment of Pb, Cs and other alkaline elements in the basanites indicates the close concern of fluids, and the Sr-Nd isotope characteristics of the basanites (low 87Sr/86Sr and 143Nd/144Nd ratios relative to those of basaltic rocks in the volcanic front) are consistent with across arc isotopic variations of the Izu-Bonin volcanic arc. The metasomatism of the source mantle by carbonatite (or carbonate-rich) melt was associated with and potentially facilitated by the infiltration and interaction of some volatile components (CO2, H2O) from the subducting slab. Thus, it is presumed that the enriched and metasomatized mantle parts have been present, ubiquitously in some regions of the mantle wedge, and that the basanitic magma, as in the Nanzaki, has been generated in close association with the unique tectonic regime, as in the northernmost part of the Izu-Bonin volcanic arc where three (or four) plates converged. © 2013 Elsevier B.V.

Ishizawa Y.,Progress Technologies Inc. | Matsumoto K.,Progress Technologies Inc. | Sato K.,University of Tokyo | Okatsu K.,Japan National Oil Corporation | Miyake Y.,Japan National Oil Corporation
Energy Procedia | Year: 2013

It is very important to evaluate the soundness of the injection site by simulating the behavior of carbon dioxide injected into the reservoir. Monte Carlo approach is often used for the statistical evaluation of reservoir because its models include much uncertainty. This approach requires a large number of simulations and it is very time consuming. Therefore we accelerated the simulation with GPU (Graphics Processing Unit) computing technology. We used the simulator called TOUGH2/ECO2N. As a result, we achieved acceleration rate more than 8 times with the simulation for the three-dimensional reservoir model of the Nagaoka project site having 110,000 grids.

Hayashi Y.,Japan National Oil Corporation
Journal of the Japan Petroleum Institute | Year: 2014

A method for determination of the solubilities of methane and carbon dioxide in high-pressure water was developed by direct injection of the sample into a gas chromatograph column. This method used a DVB-EVBEGDMA packings (80-100 mesh) packed column (3 mm i.d.×2 m). The column temperature and carrier gas flowrate were optimized for the separation of methane, carbon dioxide and water. The measurement accuracy was greatly improved by installing a check valve in the gas supply system. Solubilities of methane and carbon dioxide were determined from the values obtained from the absolute calibration curve.

Uchida S.,University of Cambridge | Soga K.,University of Cambridge | Yamamoto K.,Japan National Oil Corporation
Journal of Geophysical Research: Solid Earth | Year: 2012

This paper presents a new constitutive model that simulates the mechanical behavior of methane hydrate-bearing soil based on the concept of critical state soil mechanics, referred to as the "Methane Hydrate Critical State (MHCS) model". Methane hydrate-bearing soil is, under certain geological conditions, known to exhibit greater stiffness, strength and dilatancy, which are often observed in dense soils and also in bonded soils such as cemented soil and unsaturated soil. Those soils tend to show greater resistance to compressive deformation but the tendency disappears when the soil is excessively compressed or the bonds are destroyed due to shearing. The proposed model represents these features by introducing five extra model parameters to the conventional critical state model. It is found that, for an accurate prediction of ground settlement, volumetric yielding plays an important role when hydrate soil undergoes a significant change in effective stresses and hydrate saturation, which are expected during depressurization for methane gas recovery. Copyright 2012 by the American Geophysical Union.

Handa T.,Tokyo Institute of Technology | Lim C.-P.,Tokyo Institute of Technology | Takase Y.,Tokyo Institute of Technology | Miyanaga K.,Tokyo Institute of Technology | And 2 more authors.
Journal of Chemical Engineering of Japan | Year: 2010

The water samples collected from two non water-flooded oil fields contained a variety of organic acids, sulfatereducing bacteria (SRB) and little sulfate. Acetate and propionate were the major components of organic acids. Over 6 weeks of artificial souring experiment, a maximum of 3 mM of sulfide was produced when oil field water was mixed with seawater at 25°C. Propionate was completely consumed under soured conditions. This indicated that the propionate-consuming SRB underwent souring in this experiment. Significant cell growth was confirmed at 25°C with no relation to souring. The dominant SRB species were shifted from Desulfomicrobium thermophilum to Desulfobacter vibrioformis and uncultured Desulfobacter © 2010 The Society of Chemical Engineers, Japan.

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