Apparatus and method for clock shift correction for measurement-while-drilling measurements

摘要

The disclosure provides a method which includes transmitting signals over a time period between a downhole location and a surface location during drilling of a wellbore; recording the time of each signal at the surface using a surface clock and the time of each signal downhole using a downhole clock; and correcting the downhole measurements using the recorded times.

主权项

1. A method for correcting downhole measurements; comprising:
taking a plurality of measurements over a time period during drilling of a wellbore using a sensor; recording times of taking the plurality of measurements using a first clock at a first location in the wellbore; transmitting a synchronization signals through a fluid in the wellbore by a transmitter generated at the first location during drilling of the wellbore; recording a time of transmitting the synchronization signal using the first clock associated with the first location; receiving the synchronization signals at a second location; recording a time of receiving the synchronization signal using a second clock associated with the second location; determining a time delay for the synchronization signal using a distance between the first location and the second location and a speed of sound in the fluid in the wellbore; retrieving the measurements from the wellbore after the time period; determining a time drift relation between the first clock and the second clock using the determined time delay; and using the determined time drift relation to correct the plurality of times at which the measurements are taken over the time period.