SP profile along a survey line passing through the central part of the Okuaizu geothermal field in Japan. The red line shows the SP profile under natural state conditions, measured in 1982-83. The survey in November 1996 was carried out about 1.5 years after start-up of the Yanaizu-Nishiyama power station. The repeated surveys in 1998 were carried out after 2 months shut-in of production wells in April and May 1998, after [171, 172].
