Shear-wave splitting of acoustic emissions (AE) was analyzed to obtain a description and evaluation of subsurface cracks in a natural geothermal reservoir. During shutdown operations of production wells in 1984-1986 at the Kakkonda (Takinoue) geothermal power plant, Japan, several thousand AE events were located with a downhole tri-axial AE sonde. A total of 145 of these events showed shear-wave splitting and they were used to estimate depth and crack density of multiple layers in the reservoir. The shear-wave polarization was used to determine the orientation of the cracks, and crack density was calculated from delays between shear-wave polarization-anomalies. The reservoir was divided into three zones based on observed characteristics of the shear wave splitting. These zones are identified as the injection, production and intermediate zones.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Geotechnical Engineering and Engineering Geology