Method of noise removal for cascaded sweep data

• US 6,842,701 B2
• Filed: 02/25/2002
• Issued: 01/11/2005
• Est. Priority Date: 02/25/2002
• Status: Expired due to Fees

• Current Assignee: WesternGeco LLC (Schlumberger NV)
• Original Assignee: WesternGeco LLC (Schlumberger NV)
• Inventors: Barr, Frederick J., Moerig, Rainer
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Taylor, Victor J.
• Application Number:
  US10/082,570
• Publication Number:
  US 20030163260A1
• Time in Patent Office: 1,051 Days
• Field of Search: 702/14, 702/1, 702/2, 702/17, 703/5, 367/38, 367/41, 367/48, 367/75, 367/40, 367/73
• US Class Current: 702/14
• CPC Class Codes: G01V 1/37 specially adapted for seismic systems using continuous agitation of the ground , e.g. using pulse compression of frequency swept signals for enhancement of received signals
• CPC Class Codes: G01V 2210/32 Noise reduction

Abstract

The present invention is a method for processing seismic data comprising acquiring seismic data using a sweep sequence including a plurality of cascaded sweep segments. The seismic data include a plurality of data segments and a listen time. The listen is combined with an initial data segment. The seismic data segments are phase shifted to a phase of a target data segment to be denoised (i.e. removal of ambient, harmonic and coherent noise). A difference between the target data segment and the remaining data segments is determined. If the determined difference exceeds a predetermined threshold, data in the target data segment is replaced with data derived from the remaining data segments. The data segments may be stacked to form a new target data segment. The listen time is extracted from the initial data segment.

Claims

1. A method for processing seismic data comprising:

(a) determining a difference for data in a window comprising a portion of a first data segment with data in a corresponding window comprising a portion of a second data segment, wherein said first data segment and said second data segment are selected from a plurality of data segments acquired using a plurality of seismic sweeps; and

(b) changing said data in said first data segment using said data in a corresponding window comprising a portion of a second data segment based on said difference.

2. The method of claim 1, wherein changing said data in said first data segment further comprises replacing said data in a window using said data in a corresponding window.

3. The method of claim 1 further comprising stacking said plurality of data segments to form a new data segment.

4. The method of claim 3 further comprising extracting a listen time from said new data segment.

5. The method of claim 1 wherein said plurality of data segments each comprise a recorded data and a listen time.

6. The method of claim 1 further comprising phase shifting said second data segment to a phase corresponding to said first data segment.

7. The method of claim 1 wherein said second data segment comprises a combination of a plurality of said plurality of data segments.

8. The method of claim 7 wherein said combination comprises combining said plurality of said plurality of data segments using at least one of:

i) an arithmetic average, ii) a median average, and iii) a weighted average.

9. The method of claim 1 further comprising using RMS values for determining said difference in said data in a window of a first data segment with said data in a window of a second data segment.

10. The method of claim 1 wherein a listen time data segment is combined with an initial data segment by time series addition.