Seismic exploration method and apparatus for cancelling non-uniformly distributed noise

• US 4,890,264 A
• Filed: 03/21/1988
• Issued: 12/26/1989
• Est. Priority Date: 03/21/1988
• Status: Expired due to Term

• Current Assignee: Atlantic Richfield Company (BP PLC)
• Original Assignee: Atlantic Richfield Company (BP PLC)
• Inventors: Martinez, David R., Crews, Gary A.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): Lobo, Ian J.
• Application Number:
  US07/171,113
• Time in Patent Office: 645 Days
• Field of Search: 181/112, 367/38, 367/43, 367/45, 367/907, 364/421
• US Class Current: 367/45
• CPC Class Codes: G01V 1/364 Seismic filtering G01V1/37 takes precedence
• CPC Class Codes: G01V 2210/27 Other pre-filtering
• CPC Class Codes: G01V 2210/324 Filtering

Abstract

A seismic exploration method and apparatus in which non-uniformly distributed noise signals generated by wind, machinery, or surface wave propagation and received by the sensing geophones are cancelled by the utilization of adaptive filter processing. A number of horizontally sensitive geophones are disposed along the surface of the earth to detect surface waves induced in the surface of the earth at a plurality of spaced locations throughout an entire area of investigation. Similarly, a number of wind noise and mechanical noise detectors are utilized to detect airwave and noise signals at a plurality of locations throughout the area of investigation. The outputs of the surface wave detectors, the wind noise detectors and the mechanical noise detectors may then be utilized in conjunction with an adaptive filter to effectively cancel the effects of such interferences on reflected seismic wave signals at multiple locations throughout the area of investigation so that non-uniformly distributed noise signals may be accurately eliminated.

Claims

1. A method of seismic exploration comprising the steps of:

generating and applying seismic waves to the surface of the earth, said waves traveling into the earth and reflecting from formations in the earth and also traveling along the surface of the earth in a nonuniformly distributed manner;

placing a plurality of seismic detectors on the surface of the earth at a plurality of locations spaced on the surface of the earth from the point of application of said seismic waves for receiving said seismic waves reflecting from formations in the earth;

placing at each of said plurality of locations at least one surface wave detector adapted to receive said nonuniformly distributed surface waves;

placing at least one mechanical noise detector adapted to receive mechanical noise signals proximate to a source of nonuniform mechanical noise; and

adaptively processing said seismic waves received at each of said plurality of locations in combination with said nonuniformly distributed surface waves received at each of said plurality of locations and said received mechanical noise signal to produce an output signal representative of seismic waves reflecting from formations in the earth.

2. An apparatus for seismic exploration in the vicinity of one or more sources of non-uniform mechanical noise, comprising:

means for generating seismic waves at a selected location on the earth'"'"'s surface;

a plurality of seismic detectors disposed on the surface of the earth at a plurality of locations spaced from said selected location for receiving said seismic waves;

at least one mechanical noise detector disposed in proximity to each of said sources of non-uniform mechanical noise for detecting noise signals; and

adaptive filter means coupled to the output of each of said plurality of seismic detectors in the vicinity of a source of non-uniform mechanical noise and the output of said at least one mechanical noise detector for producing an output signal representative of seismic waves reflecting from formations in the earth wherein noise signals are removed from said seismic waves.

3. An apparatus for seismic exploration according to claim 2 wherein said means for generating seismic waves comprises a vibrational source.

4. An apparatus for seismic exploration according to claim 2 wherein said plurality of seismic detectors comprises a plurality of vertically sensitive geophones.

5. An apparatus for seismic exploration according to claim 2 wherein said adaptive filter means comprises an adaptive processor and a combining means and wherein the output of said adaptive processor is subtracted from the output of each of said plurality of seismic detectors by said combining means to produce an output signal representative of seismic waves reflecting from formations in the earth.

6. An apparatus for seismic exploration comprising:

means for generating seismic waves at a selected location on the earth'"'"'s surface;

a plurality of seismic detectors disposed on the surface of the earth at a plurality of locations spaced from said selected location for receiving said seismic waves;

at least one air noise detector at each of said plurality of locations for detecting nonuniformly distributed air noise signals; and

adaptive filter means coupled to the output of each of said plurality of seismic detectors and the output of said at least one wind noise detector at each of said plurality of locations for producing an output signal representative of seismic waves reflecting from formations in the earth wherein said nonuniformly distributed air noise signals are removed from said seismic waves.

7. An apparatus for seismic exploration according to claim 6 wherein said means for generating seismic waves comprises a vibrational source.

8. An apparatus for seismic exploration according to claim 7 wherein said plurality of seismic detectors comprises a plurality of vertically sensitive geophones.

9. An apparatus for seismic exploration according to claim 6 further including at least one surface wave detector at each of said plurality of locations adapted to receive non-uniformly distributed surface waves induced along the surface of the earth by said means for generating seismic waves.

10. An apparatus for seismic exploration according to claim 9 wherein said adaptive filter means is coupled to output of said at least one surface wave detector wherein said nonuniformly distributed surface waves are removed from said seismic waves.

11. An apparatus for seismic exploration according to claim 10 wherein each of said surface wave detectors comprises a horizontally sensitive geophone.

12. An apparatus for seismic exploration according to claim 11 wherein each of said horizontally sensitive geophones is disposed along the surface of the earth directed at said means for generating seismic waves,

13. An apparatus for seismic exploration according to claim 12 wherein said adaptive filter means comprises an adaptive processor and a combining means and wherein the output of said adaptive processor is subtracted from the output of each of said plurality of seismic detectors by said combining means to produce an output signal representative of seismic waves reflecting from formations in the earth.