Patent ID: 6023658
Filing Date: 2000-02-08
Classification: E21B,G01V

Abstract:
A noise filtering apparatus for wellbore telemetry data signals, comprising:a receiver located on the surface and adapted to receive a wellbore telemetry data signal, said telemetry data signal including data which represents one or more downhole measurements conducted downhole during a drilling operation, the data being unknown to the receiver prior to reception;a transformer in communication with said receiver and adapted to transform at least part of the telemetry data signal to generate therefrom a spectrum of at least part of the telemetry data signal;an approximator in communication with said transformer adapted to generate an approximation of a noise-free spectrum of the at least part of the telemetry data signal;a ratio calculator in communication with said approximator adapted to generate a dimensionless spectrum by calculating the ratio of the spectrum of at least part of the telemetry data signal and the approximation of a noise-free spectrum; andan identifier in communication with said ratio calculator adapted to analyze the dimensionless spectrum and select frequencies from said dimensionless spectrum that are characterized by a substantial level of noise.