How hot is it? (A comparison of advanced technology temperature logging systems)

Field tests were conducted on four `state of the art' temperature logging systems. They are: a conventional `electric-line' system; two separate pressure and temperature sensing `memory tool' computer systems; and a distributed optical fiber temperature sensing (DTS) system. The tools produced temperature versus depth and temperature gradient versus depth logs that were coincident within the `noise' level. The multiple independent logs demonstrated that most of the `noise' seen in gradient logs is due to convection cells in the borehole and to meter scale lithology changes outside the hole. These systems had various strong points, but all provided accurate, detailed, cost effective measurements in the field.