Apparatus and method for the suppression of microphonic noise in proportional counters for borehole logging-while-drilling

• Main Authors: HOLENKA, JACQUES M, SLOAN, W. ROBERT, KURKOSKI, PHILIP L
• Format: Patent
• Language: English; French; German
• Published: 19.05.1999
• Edition: 6
• Subjects: DETECTING MASSES OR OBJECTS; EARTH DRILLING; EARTH DRILLING, e.g. DEEP DRILLING; FIXED CONSTRUCTIONS; GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; MEASUREMENT OF NUCLEAR OR X-RADIATION; MEASURING; MINING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR ASLURRY OF MINERALS FROM WELLS; PHYSICS; TESTING

A method and apparatus is disclosed for suppressing microphonic noise in proportional counter neutron detection in borehole logging-while-drilling measurements. Noise is reduced by (1) applying the outputs of two detectors respectively to positive and negative inputs of a differential amplifier; (2) generating output pulses by applying the output of the differential amplifier to positive and negative comparators to produce first and second output pulses; (3) counting output pulses as neutron counts only if the first or second output pulses have time lengths less than a predetermined time length; and (4) rejecting the output pulses in the count of pulses as neutron counts if first and second output pulses coincide in time.