Patent ID: 6400646
Filing Date: 2002-06-04
Classification: E21B,G01V,G04G,H04L

Abstract:
A system for determining a clock offset between a second clock on a drill string and a first clock on the drill string, said system comprising:a first acoustic apparatus associated with said first clock, said apparatus comprising: a first transmitter configured to transmit a reset acoustic signal; a first signal processor configured to reset the first clock as the reset acoustic signal is transmitted; and a second acoustic apparatus associated with said second clock, said apparatus comprising: a second receiver configured to receive the reset acoustic signal; a second signal processor configured to reset the second clock as the reset signal is received; a second transmitter configured to transmit a return acoustic signal at a predetermined time after the second clock is reset; wherein the first acoustic apparatus further comprises a receiver configured to receive the return acoustic signal; wherein the first signal processor is further configured to determine the clock offset from a measured time interval between transmitting the reset acoustic signal and receiving the return acoustic signal.