| Title | 3D Seismic Survey for Geothermal Reservoir Imaging in the Yamagawa Geothermal Field, Southwestern Japan |
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| Authors | M. Fukuda, N. Aoki, K. Satoh, T. Nibe, S. Abe, T. Tosha |
| Year | 2016 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | 3D, Seismic Survey, Reflection survey, Refraction Survey, R&D, JOGMEC, Yamagawa, Japan, |
| Abstract | Japan Oil, Gas and Metals National Corporation (JOGMEC) is engaged in a technology development project for geothermal reservoir exploration. This project aims to develop an effective method to get an accurate image of reservoir structure, and to improve the geothermal model. Most of the geothermal reservoirs in Japan are composed of steeply dipping faults or fracture zones. Gravity and electromagnetic surveys are commonly conducted to identify reservoir structure and find caprocks and geothermal fluids. However, there is a considerable difference between these survey resolutions and distributions of faults or fracture zones detected by drilling or wellbore imaging. To fill this gap, we focused our attention on a seismic method to reveal the detailed reservoir structure with a higher spatial resolution, applying seismic method to geothermal reservoir exploration, conducting a 3D seismic reflection and refraction survey to verify the method, and obtaining experimental solutions. The Survey was designed with goal of obtaining sufficient resolution to identify fractures and faults. We acquired data with the combination of 3,262 shot points and 4,989 receiver points and processed the data with appropriate static correction and noise reduction, which is one of the most important procedures. 3D seismic data volume was interpreted through integrating the seismic data with the well data. Estimated horizon of the upper Nansatsu formation shows consistency with the conventional geological conceptual model. We also applied coherence analysis to obtain semblance attributes that indicate the location of horizontal discontinuities of reflection events. Some indications are distributed in the injection zone and the peripheries of the intruded dacite, margins of which are detected as production zones. |