Progress in the HDR/HWR projects at Tohoku University, Japan

Triaxial drill bit Vertical Seismic Pro_le "TAD VSP#\ which utilizes the drill bit as a seismic source\ was used during exploration of the deep portion of the Kakkonda geothermal system\ Japan[ The seismic signal associated with the bit was recorded continuously during the drilling of well WD!0a\ from a depth of 0494 to 2999 m[ The result of the TAD VSP shows possible seismic re~ectors at about 1[0\ 1[1\ 1[3 and 1[7km below sea level[ Based on drill hole lithology\ these re~ectors appear to correspond to the top of the Pre!Tertiary formation\ the top of the Kakkonda granite and re~ectors within the Kakkonda granite[ 0887 CNR[ Published by Elsevier Science Ltd[ All ri`hts reserved