Systems and methods for well data analysis

• US 8,136,395 B2
• Filed: 12/31/2007
• Issued: 03/20/2012
• Est. Priority Date: 12/31/2007
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Pop, Julian, Follini, Jean-Marc
• Primary Examiner(s): Williams, Hezron E
• Assistant Examiner(s): BELLAMY, TAMIKO D
• Application Number:
  US11/968,026
• Publication Number:
  US 20090165548A1
• Time in Patent Office: 1,541 Days
• Field of Search: 731/525.1, 731/522.7, 166/250.01, 702/6, 175/40, 175/48
• US Class Current: 73/152.51
• CPC Class Codes: E21B 49/008 by injection test; by analysing pressure variations in an injection or production test, e.g. for estimating the skin factor measuring pressure E21B47/06

Abstract

Examples of techniques for analyzing well data which may be encountered during formation testing are disclosed. Certain portions of the tests may exhibit an indication of anomalous behavior, defects, errors or events that may have occurred during testing. One or more confidence tokens may be identified during or after the execution of a test. One or more of these confidence tokens may be analyzed to determine whether such anomalous behavior, defects, errors or events have occurred during the test. These confidence tokens may then be used to determine a level of confidence in the results derived from the tests performed and/or their underlying data and interpretation.

Claims

1. A method for determining a confidence in measurements taken by a while drilling testing tool positioned in a wellbore penetrating a subterranean formation, the method comprising:

establishing a pressure coupling between a pressure sensor conveyed by the testing tool and the formation;

performing a first drawdown with the testing tool;

measuring data indicative of pressure with the pressure sensor;

determining at least one confidence token based on the pressure data;

identifying a downhole condition based on the measured data and the at least one confidence token; and

displaying at the surface the measured data, the at least one confidence token, and the identified downhole condition.

2. The method of claim 1 further including a second drawdown.

3. The method of claim 2 wherein the second drawdown parameters are based at least in part on the at least one confidence token.

4. The method of claim 2 wherein the confidence token is determined using a parameter comparison technique.

5. The method of claim 1 further including terminating the pressure coupling.

6. The method of claim 1 wherein determining the at least one confidence token comprises determining the at least one confidence token based on the measured data using a trend analysis technique.

7. The method of claim 6 wherein the trend analysis technique is a global trend analysis technique.

8. The method of claim 6 wherein the trend analysis technique comprises reflecting pressure data beyond the end of a buildup cycle.

9. The method of claim 8 wherein the at least one confidence token is representative of a slope of a pressure curve at an end of a buildup cycle.

10. The method of claim 1 wherein determining the at least one confidence token comprises determining the at least one confidence token based on the measured data using a scattering analysis technique.

11. The method of claim 10 wherein the scattering analysis technique is a global scattering analysis technique.

12. The method of claim 1 further comprising determining a second confidence token based on the measured data using a pressure comparison technique.

13. The method of claim 1 further comprising determining a second confidence token based on the measured data using a parameter prediction technique.

14. The method of claim 1 further comprising determining a second confidence token based on the measured data using a model correlation technique.

15. The method of claim 1 further comprising determining a second confidence token based on the measured data using a gauge comparison technique.

16. The method of claim 1 further comprising determining a second confidence token based on the measured data using a supercharging technique.

17. The method of claim 1 further comprising:

selecting a plurality of downhole conditions;

associating a different value to each of the plurality of the downhole conditions; and

transmitting to the surface display a value associated with the identified downhole condition;

wherein displaying the identified downhole condition at the surface comprises displaying indicia indicative of the identified downhole condition, and wherein the indicia comprises or is based on the value associated with the identified downhole condition.

18. A method for determining a confidence in measurements taken by a while drilling testing tool positioned in a wellbore penetrating a subterranean formation, the method comprising:

establishing a pressure coupling between a pressure sensor conveyed by the testing tool and the formation;

performing a first drawdown with the testing tool;

measuring data indicative of pressure with the pressure sensor;

determining at least one confidence token based on the pressure data;

identifying a downhole condition based on the measured data and the at least one confidence token;

selecting a plurality of downhole conditions;

associating a different value to each of the plurality of the downhole conditions;

identifying a plurality of events associated with operation of the testing tool;

selecting data points for transmission by the testing tool, the data points being selected as a function of the plurality of events and a growth function;

determining values associated with the plurality of events and the data points selected for transmission by the testing tool; and

transmitting to the surface, and displaying on a well log at the surface, the measured data, the at least one confidence token, the identified downhole condition, the determined values associated with the plurality of events and the selected data points, and a value associated with the identified downhole condition;

wherein transmitting and displaying the identified downhole condition comprises transmitting and displaying indicia indicative of the identified downhole condition, and wherein the indicia comprises or is based on the value associated with the identified downhole condition.

19. A method for determining a confidence in measurements taken by a while drilling testing tool positioned in a wellbore penetrating a subterranean formation, the method comprising:

establishing a pressure coupling between a pressure sensor conveyed by the testing tool and the formation;

performing a first drawdown with the testing tool;

measuring data indicative of pressure with the pressure sensor;

determining at least one confidence token based on the pressure data;

identifying a downhole condition based on the measured data and the at least one confidence token;

selecting data points for transmission by the testing tool, the data points being selected as a function of a growth function and a plurality of events associated with operation of the testing tool;

determining values associated with the plurality of events and the data points for transmission by the testing tool; and

transmitting to and displaying at the surface the measured data, the at least one confidence token, the identified downhole condition, and the determined values.

20. The method of claim 19 wherein displaying at the surface the measured data, the at least one confidence token, the identified downhole condition, and the determined values comprises displaying on a well log.