Method and apparatus for generating weighted average survey

• US 10,323,501 B2
• Filed: 03/08/2013
• Issued: 06/18/2019
• Est. Priority Date: 04/20/2012
• Status: Active Grant

• Current Assignee: Gyrodata Incorporated
• Original Assignee: Gyrodata Incorporated
• Inventors: Weston, John Lionel, Mullin, Stephen Victor, Ekseth, Roger
• Primary Examiner(s): Kundu, Sujoy K
• Assistant Examiner(s): Dinh, Lynda
• Application Number:
  US13/791,603
• Publication Number:
  US 20130282290A1
• Time in Patent Office: 2,293 Days
• Field of Search: 702 6- 9
• CPC Class Codes: E21B 44/00 Automatic control systems specially adapted for drilling operations, i.e. self-operating systems which function to carry out or modify a drilling operation without intervention of a human operator, e.g. computer-controlled drilling systems; Systems specially adapted for monitoring a plurality of drilling variables or conditions
• CPC Class Codes: E21B 47/00 Survey of boreholes or wells monitoring pressure or flow of drilling fluid E21B21/08
• CPC Class Codes: E21B 47/022 of the borehole, e.g. using geomagnetism
• CPC Class Codes: E21B 47/092 by detecting magnetic anomalies
• CPC Class Codes: G01V 1/46 Data acquisition
• CPC Class Codes: G01V 9/00 Prospecting or detecting by methods not provided for in groups G01V1/00 - G01V8/00
• CPC Class Codes: G06F 17/00 Digital computing or data processing equipment or methods, specially adapted for specific functions information retrieval, database structures or file system structures therefor G06F16/00

Abstract

A computer-based method of generating a survey of a wellbore section is provided. The method includes analyzing a plurality of surveys of the wellbore section to identify survey measurements that do not comprise gross errors, generating an initial weighted average survey, and calculating an initial set of measurement differences between the identified survey measurements and the initial weighted average survey. The method further includes calculating a plurality of error term estimates for the plurality of surveys and using the plurality of error term estimates to correct the identified survey measurements. The method further includes generating an updated weighted average survey and calculating an updated set of measurement differences between the identified survey measurements and the updated weighted average survey.

Claims

1. A method of generating a survey of a wellbore section, the method comprising:

acquiring first survey measurements for a first survey of the wellbore section using at least one first survey sensor, and acquiring second survey measurements for a second survey of the wellbore section using at least one second survey sensor;

analyzing the first survey of the wellbore section to identify survey measurements of the first survey that do not comprise first gross errors, and analyzing the second survey of the wellbore section to identify survey measurements of the second survey that do not comprise second gross errors;

generating an initial weighted average survey by combining the identified survey measurements of the first survey multiplied by a first initial weighting function and the identified survey measurements of the second survey multiplied by a second initial weighting function;

calculating a first set of measurement differences between the identified survey measurements of the first survey and the initial weighted average survey, and calculating a second set of measurement differences between the identified survey measurements of the second survey and the initial weighted average survey;

(a) calculating a first estimate of error terms for the first survey using the first set of measurement differences, and calculating a second estimate of error terms for the second survey using the second set of measurement differences;

(b) using the first estimate of error terms to correct the identified survey measurements of the first survey, and using the second estimate of error terms to correct the identified survey measurements of the second survey;

(c) generating an updated weighted average survey by combining the corrected identified survey measurements of the first survey multiplied by a first corresponding weighting function and the corrected identified survey measurements of the second survey multiplied by a second corresponding weighting function;

(d) calculating an updated first set of measurement differences between the identified survey measurements of the first survey and the updated weighted average survey, and calculating an updated second set of measurement differences between the identified survey measurements of the second survey and the updated weighted average survey;

(e) using the updated first set of measurement differences and the updated second set of measurement differences, iterating (a)-(d) until one or more conditions for terminating the iterations are met; and

steering a wellbore drilling tool based on the updated weighted average survey after the iterations are terminated.

2. The method of claim 1, wherein calculating the first estimate of error terms comprises using a first least squares estimation and calculating the second estimate of error terms comprises using a second least squares estimation.

3. The method of claim 1, wherein the first survey and the second survey are independent of one another.

4. The method of claim 1, wherein the second survey sensor is different from the first survey sensor.

5. The method of claim 1, wherein the identified survey measurements from the at least one first survey sensor have a first accuracy and the identified survey measurements from the at least one second survey sensor have a second accuracy different from the first accuracy.

6. The method of claim 1, wherein the first survey and the second survey are inclination surveys, wherein at least one of the first survey and the second survey was generated by one or more accelerometers and has error terms resulting from at least one of the group consisting of:

inclination offset, residual bias, and sag.

7. The method of claim 1, wherein the first survey and the second survey are azimuth surveys, wherein at least one of the first survey and the second survey was generated by one or more gyroscopes and has error terms resulting from at least one of the group consisting of:

residual bias, mass unbalance offset, and linear drift.

8. The method of claim 7, wherein at least one of the first survey and the second survey comprises a stationary gyroscopic survey.

9. The method of claim 7, wherein at least one of the first survey and the second survey comprises a continuous gyroscopic survey.

10. The method of claim 1, wherein the first survey and the second survey are azimuth surveys, wherein at least one of the first survey and the second survey was generated by one or more magnetic sensors and has error terms resulting from axial magnetic interference.

11. The method of claim 1, wherein the first initial weighting function is different from the second initial weighting function.

12. The method of claim 1, wherein the first initial weighting function comprises error variances of the identified survey measurements of the first survey, and the second initial weighting function comprises error variances of the identified survey measurements of the second survey.

13. The method of claim 1, wherein the first corresponding weighting function is the first initial weighting function and the second corresponding weighting function is the second initial weighting function.

14. The method of claim 1, wherein generating the updated weighted average survey comprises calculating the first corresponding weighting function by updating the first initial weighting function and calculating the second corresponding weighting function by updating the second initial weighting function.

15. The method of claim 1, wherein acquiring the first survey measurements and acquiring the second survey measurements occur at least partially while drilling the wellbore section.

16. The method of claim 1, wherein the one or more conditions comprises:

the updated first set of measurement differences and the updated second set of measurement differences are within a predetermined tolerance;

a maximum number of iterations has been met;

or

combinations thereof.

17. A system for generating a survey of a wellbore section, the system comprising:

at least one first survey sensor configured to acquire first survey measurements for a first survey of the wellbore section; and

at least one second survey sensor configured to acquire second survey measurements for a second survey of the wellbore section; and

one or more hardware processors in communication with at least one computer-readable memory that stores software modules including instructions that are executable by the one or more hardware processors, the software modules including at least;

an analysis computer module configured to identify survey measurements of the first survey and the second survey that do not comprise gross errors;

a weighted average survey computer module configured to calculate a weighted average survey based on the identified survey measurements of the first survey multiplied by a first weighted function and the identified survey measurements of the second survey multiplied by a second weighted function;

a difference computer module configured to calculate a first set of measurement differences between the identified survey measurements of the first survey and the weighted average survey and to calculate a second set of measurement differences between the identified survey measurements of the second survey and the weighted average survey;

an error computer module configured to calculate a first estimate of error terms for the first survey using the first set of measurement differences and to calculate a second estimate of error terms for the second survey using the second set of measurement differences;

a correction computer module configured to use the first estimate of error terms to correct the identified survey measurements of the first survey and to use the second estimate of error terms to correct the identified survey measurements of the second survey;

a control computer module configured to provide the corrected identified survey measurements of the first survey and the corrected identified survey measurements of the second survey to the weighted average survey computer module to generate an updated weighted average survey, wherein the weighted average survey computer module, the difference computer module, the error computer module, the correction computer module, and the control computer module are iteratively used until one or more conditions for terminating the iterations are met; and

a wellbore drilling tool configured to be steered based on the updated weighted average survey after the iterations are terminated.

18. The system of claim 17, wherein the at least one second survey sensor is different from the at least one first survey sensor.

19. The system of claim 18, wherein the first survey and the second survey are inclination surveys, wherein at least one of the first survey sensor and the at least one second survey sensor comprise one or more accelerometers with error terms resulting from at least one of the group consisting of:

inclination offset, residual bias, and sag.

20. The system of claim 18, wherein the first survey and the second survey are azimuth surveys, wherein at least one of the first survey sensor and the at least one second survey sensor comprise one or more gyroscopes with error terms resulting from at least one of the group consisting of:

residual bias, mass unbalance offset, and linear drift.

21. The system of claim 18, wherein the first survey and the second survey are azimuth surveys, wherein at least one of the first survey sensor and the at least one second survey sensor comprise one or more magnetic sensors with error terms resulting from axial magnetic interference.

22. The system of claim 17, wherein the at least one computer-readable memory further stores at least the first survey, the second survey, and at least one updated weighted average survey.

23. The system of claim 17, wherein the error computer module is further configured to calculate the first estimate of error terms for the first survey using a first least squares estimation and to calculate the second estimate of error terms for the second survey using a second least squares estimation.

24. The system of claim 17, wherein the first weighting function is different from the second weighting function.

25. The system of claim 17, wherein the first weighed function comprises error variances of the identified survey measurements of the first survey, and the second weighting function comprises error variances of the identified survey measurements of the second survey.

26. The system of claim 17, wherein the one or more conditions comprises:

an updated first set of measurement differences and an updated second set of measurement differences are within a predetermined tolerance;

a maximum number of iterations has been met;

or

combinations thereof.

27. A system, comprising:

at least one survey sensor configured to acquire a plurality of survey measurements for a plurality of surveys of a wellbore section;

one or more processors;

at least one memory comprising instructions which, when executed by the one or more processors, cause the one or more processors to;

analyze the plurality of surveys of the wellbore section to identify survey measurements of the plurality of surveys that do not comprise gross errors;

generate an initial weighted average survey by combining the identified survey measurements of the plurality of surveys multiplied by initial weighting functions;

calculate a set of measurement differences between the identified survey measurements of the plurality of surveys and the initial weighted average survey;

(a) calculate a plurality of error term estimates for the plurality of surveys using the set of measurement differences;

(b) use the plurality of error term estimates to correct the identified survey measurements of the plurality of surveys;

(c) generate an updated weighted average survey by combining the corrected identified survey measurements of the plurality of surveys multiplied by corresponding weighting functions;

(d) calculate an updated set of measurement differences between the identified survey measurements of the plurality of surveys and the updated weighted average survey; and

(e) use the updated set of measurement differences, iterating (a)-(d) until one or more conditions for terminating the iterations are met; and

a wellbore drilling tool configured to be steered based on the updated weighted average survey after the iterations are terminated.