FREQUENCY-DOMAIN BAND BROADENING OF SEISMIC DATA

• US 3,581,274 A
• Filed: 03/19/1969
• Issued: 05/25/1971
• Est. Priority Date: 03/19/1969
• Status: Expired due to Term

• Current Assignee: William H. Ruehle
• Original Assignee: William H. Ruehle
• Inventors: Ruehle, William H.
• Application Number:
  US04/808,410
• Time in Patent Office: 797 Days
• US Class Current: 367/43
• CPC Class Codes: G01V 1/28 Processing seismic data, e.g. for interpretation or for event detection G01V1/48 takes precedence
• CPC Class Codes: G01V 2210/20 Trace signal pre-filtering to select, remove or transform specific events or signal components, i.e. trace-in/trace-out removing noise G01V2210/32

Abstract

The specification, in the preferred embodiment, discloses a technique for removing distortion such as multiples from seismograms by converting the traces of the seismogram by Fourier transformation into their real and imaginary parts. The envelopes of the real and imaginary parts are detected in the frequency domain and operated on to produce inverse operators which are a function of the envelopes of the real and imaginary parts. The product is formed between the real and imaginary parts of the traces and the inverse operators to remove distortion components from the real and imaginary parts of each trace. The resulting distortion-free data is transformed back into the time domain for further processing and analysis.

Claims

1. A process automatically performed in a data processing machine for reducing the effect of distortion from a seismogram comprising a plurality of traces representative of seismic energy detected at a plurality of spaced positions obtained in seismic surveying operations, comprising the steps of, in said data processing machine:

separating each trace into its complex components, forming distortion-removal functions which are a function of the envelopes of said complex components, combining said distortion-removal functions with said complex components to remove distortion components from said complex components for the production of data in the frequency domain wherein said distortion components have been removed, and transforming said data into the time domain for the production of seismic traces wherein the effect of said distortion has been reduced.

2. A method of reducing the effect of distortion from a seismogram comprising a plurality of traces representative of seismic energy detected at a plurality of spaced positions obtained in seismic surveying operations, comprising the steps of, in an automatic data processing system:

separating each trace into its complex components in the frequency domain, detecting the envelopes of said complex components to detect distortion components in said complex components, deriving from said envelopes, operators which, when combined with said complex components, remove said distortion components therefrom, combining said operators with said complex components to remove said distortion components from said complex components for the production of data in the frequency domain wherein said distortion components have been removed, and transforming said data into the time domain for the production of seismic traces wherein the effect of said distortion has been reduced.

3. A method of reducing the effect of distortion from a seismogram comprising a plurality of traces representative of seismic energy detected at a plurality of spaced positions obtained in seismic surveying operations, comprising the steps of, in an automatic data processing system:

separating each trace by Fourier transformation into its real and imaginary parts, detecting the envelopes of said real and imaginary parts, operating on said envelopes of said real and imaginary parts to produce inverse operators which are a function of said envelopes of said real and imaginary parts, forming the complex product between said real and imaginary parts and said inverse operators to remove distortion components from said real and imaginary parts for the production of data in the frequency domain wherein said distortion components have been removed, and transforming said data into the time domain for the production of seismic traces wherein the effect of said distortion has been Reduced.

4. The method of claim 3 wherein:

said operations are carried out with a Fourier transformer and a digital computer, and Fourier transformer being coupled to said computer to carry out said Fourier transformation.

5. A method of reducing the effect of distortion from a seismogram comprising a plurality of traces representative of seismic energy detected at a plurality of spaced positions obtained in seismic surveying operations, comprising the steps of, in an automatic data processing system:

separating each trace into its amplitude and phase components in the frequency domain, detecting the envelopes of said amplitude and phase components to detect distortion components, forming the inverse of said envelope detected from said amplitude component, forming the product between said inverse and said amplitude component for the production of data in the frequency domain wherein distortion components have been removed, forming the difference between said phase component and said envelope detected from said phase component for the production of data in the frequency domain wherein said distortion components have been removed, and transforming said data into the time domain for the production of seismic traces wherein the effect of said distortion has been reduced.

6. A method of reducing the effect of distortion from a seismogram comprising a plurality of traces in the time domain representative of seismic energy detected at a plurality of spaced positions obtained in seismic surveying operations, comprising the steps of, in an automatic data processing system:

separating each trace by Fourier transformation into its real part Re and its imaginary part Im, detecting the envelopes A( omega ) and B( omega ) of said real and imaginary parts, respectively, operating on said envelope of said real and imaginary parts to produce inverse operators,

7. A method of carrying out marine seismic operations employing a tow vessel for towing a detector system and a data processor located on said tow vessel, comprising the steps of:

generating seismic impulses in water for the application of seismic energy to the earth, detecting in water reflected seismic energy, on said tow vessel, producing a seismogram from said detecting operations and comprising a plurality of traces in the time domain representative of seismic energy detected, on said tow vessel, processing said seismogram in an automatic data processing system by carrying out the following steps;

separating each trace by Fourier transformation into its real and imaginary parts, detecting the envelopes of said real and imaginary parts and due to unwanted distortion, operating on said envelopes of said real and imaginary parts to produce inverse operators which are a function of said envelopes of said real and imaginary parts, combining said inverse operators with said real and imaginary parts to remove distortion components from said real and imaginary parts for the production of data in the frequency domain wherein said distortion components have been removed, and transforming said data into the time domain for the production of seismic traces wherein the effect of said distortion has been reduced.

8. The method of claim 7 wherein:

said operations are carried out with a Fourier transformer and a digital computer, said Fourier transformer being coupled to said computer to carry out said Fourier transformation.

9. An automatic data processing machine programmed to reduce the effect of distortion from a seismogram comprising a plurality of traces representative of seismic energy detected at a plurality of spaced positions obtained in seismic surveying operations, said data processing machine being programmed to include:

means for separating each trace by Fourier transformation into its real and imaginary parts, means for detecting the envelopes of said real and imaginary parts, means for operating on said envelopes of said real and imaginary parts to produce inverse operators which are a function of said envelopes of said real and imaginary parts, means for forming the complex product between said real and imaginary parts and said inverse operators to remove distortion components from said real and imaginary parts for the production of data in the frequency domain wherein said distortion components have been removed, and means for transforming said data into the time domain for the production of seismic traces wherein the effect of said distortion has been reduced.