The Japanese government-funded geothermal exploration Well WD-1A reached 37
29 m at total depth, where the bottomhole static temperature is more than 5
00 degrees C. A trajectory correction run was carried out with a positive d
isplacement motor and measurement while drilling tool where the formation t
emperature is greater than 350 degrees C. The combination of large surface
mud containers and sufficient mud cooling equipment were used to cool retur
n mud from the well. A top drive system was used to cool the bottomhole ass
embly while running each drillpipe stand in the hole. A borehole dynamic te
mperature experiment and drill bit tests were carried out in this well.