Mituhiko Sugihara

Geological Survey of Japan

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Yuji Nishi

Geological Survey of Japan

Kazunari Nawa

Geological Survey of Japan

Tsuneo Ishido

Geological Survey of Japan

Hiroki Goto

Juntendo University

Ayumu Miyakawa

National Institute of Advanced Industrial Science and Technology

Hiroshi Ikeda

Chiba University

Toshiyuki Tosha

Tokyo University of Marine Science and Technology

Takashi Okuda

Aichi Prefectural University

Hiroshi Ikeda

Community Care

Bradley J. Scott

GNS Science

Cooperative Institutions

National Institute of Advanced Industrial Science and Technology

Geological Survey of Japan

The University of Tokyo

Kyoto University

Association for the Development of Earthquake Prediction

Czech Academy of Sciences, Institute of Geology

Tokyo Institute of Technology

Tohoku University

Photonics Electronics Technology Research Association

Institute of Geosciences

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Gravity monitoring for CO2 sequestration using a superconducting gravimeter

Proceedings of the 11th SEGJ International Symposium, Yokohama, Japan, 18-21 November 2013 (2013)

Mituhiko Sugihara Kazunari Nawa Tsuneo Ishido Nobukazu Soma Yuji Nishi

An iGrav superconducting gravity meter was deployed in the Farnsworth field, TX for the purpose of studying the effects of CO2 injection at an enhanced oil recovery site. We made baseline measurements at the test site in cooperation with the Southwest Regional Partnership (SWP) which was established by US Department of Energy. The scale factor and drift rate of the superconducting gravimeter were evaluated by co-located measurements with an absolute gravimeter. We decomposed the 76-day continuous gravity data using the program BAYTAP-G into the trend components, tidal components and others. Generally the instrument operated well and performed within specified limits. The disturbances we encountered did not appear to affect the long period performance of the instrument which was the principal signal of interest for this study.

Gravimeter

10.1190/segj112013-045

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Repeated Self-Potential Profiling of Izu-Oshima Volcano, Japan

Journal of geomagnetism and geoelectricity (1997)

Tsuneo Ishido Tsuneo Kikuchi Nobuo Matsushima Yusaku Yano Shinsuke Nakao

Between March 1989 and March 1994, annual self-potential (SP) surveys were carried out on Izu-Oshima, a small volcanic island. A terrain-related SP distribution of about -1 mV per meter of elevation was observed outside the caldera in all five surveys. Inside the caldera, SP increases from about -350 mV to near 0 mV (relative to the coastline) as the summit crater is approached, although negative anomalies of small spatial extent are manifest. Self-potential inside the caldera decreased by about 100 mV between the March 1989 and the March 1990 surveys, which appears to be correlated with a significant decline in the degassing rate from the summit crater. After 1990, the SP distribution is quite steady along the entire survey line which extends from the west coast through the southern part of the caldera, and ends east of Ura-sabaku. Recently a postprocessor has been developed to calculate space/time distributions of electrokinetic potentials resulting from histories of underground conditions (pressure, temperature, salt concentration, flowrate etc.) computed by multiphase multi-component unsteady geothermal reservoir simulations (Ishido and Pritchett, 1996). We applied this postprocessor to a simple two-dimensional model of hydrothermal activity in a volcanic island. The low potentials in areas of high elevation are reproduced in the model, and are caused by downflow of meteoric waters. The high potential centered at the summit crater is found to be produced by upflows of volcanic gas and vapor which diminish meteoric water downflow near the volcanic conduit.

Caldera

Fumarole

10.5636/jgg.49.1267

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Citations (44)

Gravity monitoring at the Farnsworth CO2-EOR site, TX (2)

Japan Geoscience Union (2014)

Mituhiko Sugihara Kazunari Nawa Nobukazu Soma Tsuneo Ishido Ayumu Miyakawa

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Various drift rates of gPhone gravimeters obtained from short-term observations at geothermal fields

Japan Geoscience Union (2014)

Kazunari Nawa Ayumu Miyakawa Mituhiko Sugihara

Gravimeter

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Gravity monitoring at the Hachijojima geothermal field, Japan

Proceedings of the 10th SEGJ International Symposium, Kyoto, Japan, 20-22 November 2011 (2011)

Mituhiko Sugihara Kazunari Nawa Yuji Nishi Tsuneo Ishido Keiichi Sakaguchi

We have started gravity monitoring at the Hachijojima geothermal field. For the project we must distinguish local gravity changes occurring in connection with hydrothermal process of hot spring, from those of geothermal power generation, groundwater, and tidal current around the island. Continuous measurements could prove a useful tool. We are making continuous gravity measurements with a Scintrex CG3M, a CG5 and a new type of metal spring sensor gravity meter (the "gPhone") that has a large dynamic range and enough sensitivity to record the continuous background seismic and earth tide activity. Making preliminary continuous recording we confirmed the performance of the gravimeters and detected particular signals.

Gravimeter

Hot spring

Continuous monitoring

Geothermal power

10.1190/segj102011-001.120

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Revised hypocenter solutions for microearthquakes in the kakkonda geothermal field, japan

Geothermics (1998)

Toshiyuki Tosha Mituhiko Sugihara Yuji Nishi

Hypocenter

Microseism

Passive seismic

10.1016/s0375-6505(98)00033-9

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Citations (27)

Observation of gravity fluctuations due to tide-induced groundwater table fluctuations with two superconducting gravimeters

Hiroki Goto Mituhiko Sugihara Yuji Nishi Hiroshi Ikeda

<p>Estimation of aquifer hydraulic properties is necessary for predicting groundwater flow and hence managing groundwater resources. Analysis of tide-induced groundwater table fluctuations in unconfined aquifers is one of the methods to estimate aquifer properties. Changes in groundwater level affect surface gravity. Consequently, surface gravity in coastal regions is expected to fluctuate due to the groundwater table fluctuations and is potentially useful for estimating aquifer properties. Moreover, gravity measurements are sensitive to mass redistribution around the observation location and therefore are useful for estimating the storage coefficient of an aquifer. In this study, surface gravity and unconfined groundwater level were measured continuously near the coast of Japan to observe gravity fluctuations due to the tide-induced groundwater table fluctuations. Groundwater level measured in two wells at 60 and 90 m distances from the coastline fluctuated in response to ocean tides. Two superconducting gravimeters (SGs) were installed at 70 and 80 m distances from the coastline and at an elevation of 8 m. After taking the difference between gravity values recorded with the two SGs and then correcting the gravity difference for ocean loading effects, diurnal and semi-diurnal gravity fluctuations, which are possibly due to tide-induced groundwater table fluctuations, were recognized. These results suggest that gravity monitoring with two SGs at different distances from the coastline can be useful for observing gravity fluctuations due to tide-induced groundwater table fluctuations and possibly for estimating aquifer hydraulic properties.</p>

Gravimeter

Groundwater discharge

10.5194/egusphere-egu2020-19014

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Geothermal reservoir monitoring with a combination of absolute and relative gravimetry

Geophysics (2008)

Mituhiko Sugihara Tsuneo Ishido

Microgravity monitoring is a valuable tool for mapping the redistribution of subsurface mass and for assessing changes in fluid recharge from reservoir boundaries associated with geothermal exploitation. To further the development of a high-precision absolute/relative hybrid gravity-measurement technique, we conducted measurements using an absolute gravimeter in two geothermal fields in Japan. The absolute gravity measurements were performed in the central production areas to directly measure gravity changes caused by fluid withdrawal. We succeeded in measuring long-term trends within an accuracy of a few microgals in the Okuaizu and Ogiri fields, which have been producing electricity for several years. Absolute measurements in the center of the field provide reliable and local reference datum anchor points for more widely distributed relative gravity measurements. In the Ogiri field, we carried out time-lapse hybrid measurements with this combination of absolute and relative gravimetry and delineated the spatial distributions of long- and short-term changes. The long-term changes are relatively small, considering the four-year observation interval. This suggests a near balance between the mass withdrawal rate from wells and mass recharge from peripheral regions. The apparent balance is reproduced fairly well by a preliminary numerical reservoir simulation study. The observed long- and short-term changes are thought to be useful constraints for planned history-matching studies based on refined reservoir models with greater spatial resolution that incorporate detailed well-by-well production histories.

Gravimetry

Gravimeter

10.1190/1.2991105

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Citations (73)

Gravity anomaly map of Nagura River Basin, Western Ishigaki Island

Japan Geoscience Union (2018)

Ayumu Miyakawa Kazunari Nawa Yusuke Yamaya Toshiki Ohtaki Mituhiko Sugihara

Anomaly (physics)

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