Patent ID: 7193932
Filing Date: 2007-03-20
Classification: G01V

Abstract:
1. A method of recording seismic survey data comprising the steps of: a. Generating a terrestrially transmitted seismic survey event; b. Detecting seismic reflections of said event by a plurality of physically spaced sensors; c. Generating by said sensors, respective sensor signals corresponding to said seismic reflections; d. Transmitting said sensor signals along a plurality of first and second signal channels to respective first and second signal processing modules having respective independent clock means; e. Transmitting a sequentially ordered series of substantially uniformly spaced interrogate signals by a central control system having a master clock, a master clock time value being determinable for each interrogate signal transmitted by said central control system; f. Independent reception by each of said first and second signal processing modules of said interrogate signals, the time value of respective independent clock means being accumulated by said first and second signal processing modules upon receipt of said interrogate signals; g. Upon respective reception of a first interrogate signal, said signal processing modules commencing the sampling of respective sensor signals to form and record respective digital seismic values for said sensor signals at a predetermined rate, formation of said digital seismic values continued until receipt of a final interrogate signal h. Upon respective reception of a second interrogate signal by said first and second signal processing modules, respective first sets of said digital seismic values are delineated and transmitted toward said central control system; i. Repeating step h for a third and subsequent interrogation signals over a predetermined seismic recording interval to delineate and transmit second and subsequent sets of digital seismic values received between successive interrogate signals; j. Recording by said first and second signal processing modules, the time values of respective independent clock means corresponding to the moment of receipt of a predetermined fraction of said interrogate signals; k. Recording by said central control system, said digital seismic values respective to said first and second signal processing modules in responsive correlation to the sequential order of said second and subsequent interrogate signals; l. Transmitting by said first and second signal processing modules toward said central control system at the end of said predetermined interval, a functional correlation between respective independent clock time values and the sequence identity of corresponding interrogate signals among said predetermined fraction m. Determining time delay intervals corresponding to respective signal transit times between said central control system and said first and second signal processing modules; n. Applying said time delay intervals to said functional correlation to determine respective values of time drift differential between said master clock and said respective independent clock means; o. computing corrected master clock times for corresponding digital seismic values by utilizing said respective values of time drift differential: p. computing probable digital seismic values at synchronous sampling times from said recorded digital seismic values and said corrected master clock times: and, q Recording said probable digital seismic values.