Applications of a Downhole Programmable Microprocessor for a Geothermal Borehole Inspection Tool

Abstract

The high temperature scanning borehole inspection system is currently being developed jointly by the Los Alamos National Laboratory (LANL) and Westfalische Berggewerkschaftskasse (WBK) of West Germany. The downhole instruments is a digital televiewer that utilized microprocessor to digitize, process and transmit the acoustic information to the surface acquisition and control system. The primary operation of the downhole acoustic assembly uses a piezoelectric crystal acting as a receiver transmitter which is mounted on the rotating head. The crystal emits a burst of acoustic energy that propagates through the borehole fluid with a portion of the energy reflected by the borehole wall back to the crystal. The time of travel and the amplitude of the reflected signal are conditioned by the microprocessor and transmitted along with other pertinent data to the surface data processing center. This instrument has been designed specifically for use in geothermal borehole environments to determine the location of fractures intersecting the borehole and provide information concerning overall borehole conditions. It may also be used for definitive casing inspection. The instrument essentially eliminates operator interaction for downhole control and simplifies assembly and maintenance procedures