Methods of range selection for positioning marine seismic equipment

• US 20070223308A1
• Filed: 03/21/2006
• Published: 09/27/2007
• Est. Priority Date: 03/21/2006
• Status: Abandoned Application

• Current Assignee: WesternGeco LLC
• Original Assignee: WesternGeco LLC
• Inventors: Combee, Leendert, Frivik, Svein
• Application Number:
  US11/385,159
• Publication Number:
  US 20070223308A1
• Time in Patent Office: Days
• US Class Current: 367/19
• CPC Class Codes: G01S 5/26 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/28 takes precedence
• CPC Class Codes: G01V 1/38 specially adapted for water-covered areas G01V1/28 takes precedence
• CPC Class Codes: G01V 1/3835 measuring position, e.g. by GPS or acoustically

Abstract

A method for selecting a signal arrival for determining an accurate position of seismic equipment includes the steps of transmitting a signal from a pinger; predicting a direct arrival and a reflected arrival of the signal at a receiver, wherein each arrival is the time between the transmission of the signal to reception of the signal; measuring arrivals of the signal at the receiver; selecting the measured signal arrival that is similar to the predicted direct arrival as a preliminary signal arrival; defining a confidence interval for the actual direct arrival of the signal based on the predicted direct arrival and the predicted reflected arrival; and finalizing the signal arrival, wherein the selected preliminary signal arrival is the finalized signal arrival if it is within the confidence interval.

Claims

1. A method for selecting a signal arrival for determining an accurate position of seismic equipment, the method comprising the steps of:

transmitting a signal from a pinger;

measuring arrivals of the signal at a receiver, wherein each arrival is the time betveen the transmission of the signal to reception of the signal;

selecting one of the signal arrivals as a preliminary signal arrival;

calculating a confidence interval for an estimated direct arrival of the signal; and

selecting a final signal arrival, wherein the selected preliminary signal arrival is the selected final signal arrival if it is within the confidence interval.

2. The method of claim 1, wherein the step of selecting a final signal arrival further includes:

conditioning the selected preliminary signal arrival to substantially equal the estimated direct signal arrival at the receiver when the selected preliminary arrival is not within the confidence interval.

3. The method of claim 1, wherein the estimated direct signal arrival is calculated as an arrival of the signal without being reflected off a boundary.

4. The method of claim 3, wherein the estimated directed signal arrival is calculated based on the pinger-receiver geometry and a sound speed profile of the medium in which the pinger and receiver are provided.

5. The method of claim 1, further including the step of determining the position of the receiver relative to the pinger based on the selected final signal arrival.

6. The method of claim 2, wherein the estimated direct signal arrival is calculated as an arrival of the signal without being reflected off a boundary.

7. The method of claim 6, further including the step of determining the position of the receiver relative to the pinger based on the selected final signal arrival.

8. A method for selecting a signal arrival for determining an accurate position of seismic equipment, the method comprising the steps of:

transmitting a signal from a pinger;

predicting a direct arrival and a reflected arrival of the signal at a receiver, wherein each arrival is the time between the transmission of the signal to reception of the signal;

measuring arrivals of the signal at the receiver;

selecting the measured signal arrival that is similar to the predicted direct arrival as a preliminary signal arrival; and

finalizing the selected signal arrival, wherein the selected preliminary signal arrival is the finalized signal arrival if it correlates with the predicted direct arrival.

9. The method of claim 8, wherein the pinger and the receiver are provided in a marine environment.

10. The method of claim 8, wherein the step of finalizing includes the step of adjusting the selected preliminary signal arrival to substantially match the predicted direct arrival.

11. The method of claim 8, further including the step of determining the position of the receiver relative to the pinger based on the finalized signal arrival.

12. The method of claim 9, further including the step of determining the position of the receiver relative to the pinger based on the finalized signal arrival.

13. The method of claim 10, further including the step of determining the position of the receiver relative to the pinger based on the finalized signal arrival.

14. The method of claim 13, wherein the pinger and the receiver are provided in a marine environment.

15. A method for selecting a signal arrival for determining an accurate position of seismic equipment, the method comprising the steps of:

transmitting a signal from a pinger;

predicting a direct arrival and a reflected arrival of the signal at a receiver, wherein each arrival is the time between the transmission of the signal to reception of the signal;

measuring arrivals of the signal at the receiver;

selecting the measured signal arrival that is similar to the predicted direct arrival as a preliminary signal arrival;

defining a confidence interval for the actual direct arrival of the signal based on the predicted direct arrival and the predicted reflected arrival; and

finalizing the signal arrival, wherein the selected preliminary signal arrival is the finalized signal arrival if it is within the confidence interval.

16. The method of claim 15, further including the step of determining the position of the receiver relative to the pinger based on the finalized signal arrival.

17. The method of claim 15, wherein the pinger and the receiver are provided in a marine environment.

18. The method of claim 15, wherein the step of finalizing the selected arrival includes the step of adjusting the selected preliminary arrival to substantially match the predicted direct arrival when the selected preliminary arrival is not within the confidence interval.

19. The method of claim 18, further including the step of determining the position of the receiver relative to the pinger based on the finalized signal arrival.

20. The method of claim 19, wherein the pinger and the receiver are provided in a marine environment.