Remote-field eddy current based total thickness logging

Patent metadata

Field	Value
Publication number	US-10641735-B2
Application number	US-201716089293-A
Country	US
Kind code	B2
Filing date	Jun 27, 2017
Priority date	Jun 27, 2017
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

Eddy current logging enables corrosion monitoring in nested-pipe arrangements. An illustrative method of logging total thickness of the pipe walls includes acquiring measurements from an electromagnetic logging tool conveyed through the innermost bore, each measurement associated with a TRF combination (transmit antenna, receive antenna, and frequency), and further associated with a position along the bore. Multiple scale factors are applied to the measurements to determine multiple total thickness estimates for each position, each of the multiple scale factors corresponding to a subset of single-pipe defect profiles. Preferably, every possible single-pipe defect profile is included in at least one of these subsets. A total thickness log value for each position is derived from the multiple total thickness estimates for that position, and the derived total thickness log values are used to update a displayed total thickness log as the measurements are being acquired.

First claim

What is claimed:

1. A method of logging total thickness of pipe walls in a nested-pipe arrangement, the method comprising:
acquiring measurements from an electromagnetic logging tool conveyed along a bore of the nested-pipe arrangement, each measurement associated with a transmit antenna, receiver antenna, and signal frequency (TRF) combination of transmit antenna, receive antenna, and frequency, and further associated with a point along the nested-pipe arrangement;
applying multiple scale factors to the measurements to determine multiple total thickness estimates for each point along the nested-pipe arrangement, each of the multiple scale factors for measurements by a given TRF combination corresponding to a subset of single-pipe defect profiles, wherein every single-pipe defect profile for the nested-pipe arrangement is included in at least one subset for at least one of the multiple scale factors;
deriving a total thickness log value for each point along the nested-pipe arrangement from the multiple total thickness estimates for that point; and
using the derived total thickness log values to update a displayed total thickness log as the measurements are being acquired.

2. The method of claim 1 , wherein said applying includes:
subtracting, from the measurements associated with each TRF combination, a baseline measurement value for that TRF combination to obtain a phase shift;
scaling the phase shift by the scaling factor to obtain an estimated defect size; and
summing the estimated defect size with a nominal total thickness to obtain a total thickness estimate.

3. The method of claim 2 , wherein the nested-pipe arrangement is located within a borehole, and wherein each measurement and each of the multiple total thickness estimates is associated with a position along the borehole.

4. The method of claim 3 , wherein said applying further includes determining whether said
position is associated with a transition between borehole zones and if so:
performing said subtracting, scaling, summing, and using operations on any measurements from a previous zone remaining in a buffer;
flushing the buffer;
obtaining scale factors for the nested-pipe arrangement of a current zone; and
buffering measurement from the current zone to determine a new baseline measurement valve.

5. The method of claim 1 , wherein said deriving includes:
selecting a minimum total thickness estimate as the total thickness log value unless all total thickness estimates are greater than a nominal total thickness, in which case a maximum total thickness estimate is selected as the total thickness log value.

6. The method of claim 5 , wherein each of the multiple scale factors corresponds to a different subset of single-pipe defect profiles, and no two subsets have a shared single-pipe defect profile.

7. The method of claim 1 , wherein the multiple scale factors include at least one scale factor representing a sensitivity of each of multiple TRF combinations to each single-pipe defect profile.

8. The method of claim 7 , wherein said deriving includes:
calculating a standard deviation of total thickness estimates for any possible combination of defect profiles and combining or selecting from the total thickness estimates of the defect profile having a smallest standard deviation.

9. The method of claim 1 , wherein said measurements comprise a phase difference between transmitted and received signals, and wherein the scale factors represent an average sensitivity of the phase difference for the associated TRF combination to a defect size in the corresponding subset of single-pipe defect profiles.

10. A corrosion monitoring system that comprises:
a downhole electromagnetic logging tool conveyable along a bore of a nested-pipe arrangement with one or more transmit antennas operating at one or more signal frequencies to induce an eddy current in conductive walls of the nested-pipe arrangement, and further including one or more receive antennas to measure, for each of multiple combinations of transmit antenna, receive antenna, and signal frequency (“TRF combinations”), a phase difference created by the induced eddy current as a function of position; and
a processing unit coupled to the logging tool to collect, store, and process the measured phase differences to provide a total thickness log contemporaneously with said collecting and storage, wherein the processing includes:
obtaining scale factors for a current zone of the nested-pipe arrangement, each scale factor representing the sensitivity of a TRF combination to a subset of single-pipe defect profiles, wherein every single-pipe defect profile of the nested-pipe arrangement in that zone is included in at least one of said subsets;
applying the scale factors to measured phase differences of respective TRF combinations to determine a total thickness estimate for each said subset;
deriving a total thickness log value from the total thickness estimates; and
updating a displayed total thickness log with the derived log values.

11. The system of claim 10 , wherein said obtaining includes:
segmenting the nested-pipe arrangement into zones based on a well plan;
determining scale factors for each zone; and
selecting a zone containing a current position of the tool as the current zone.

12. The system of claim 11 , wherein said applying includes:
subtracting, from the measured phase differences associated with each TRF combination, a baseline measurement value for that TRF combination to obtain a phase shift;
scaling the phase shift by one of the scaling factors to obtain an estimated defect size; and
summing the estimated defect size with a nominal total thickness to obtain a total thickness estimate.

13. The system of claim 12 , wherein said applying further includes determining whether said
position is associated with a transition between zones and if so:
performing said subtracting, scaling, summing, and using operations on any measurements from a previous zone remaining in a buffer;
flushing the buffer;
buffering measured phase differences from the current zone to determine a new baseline measurement value.

14. The system of claim 10 , wherein said deriving includes:
selecting a minimum total thickness estimate as the total thickness log value unless all total thickness estimates are greater than a nominal total thickness, in which case a maximum total thickness estimate is selected as the total thickness log value.

15. The system of claim 10 , wherein each of the scale factors corresponds to a different subset of single-pipe defect profiles, and no two subsets have a shared single-pipe defect profile.

16. The system of claim 10 , wherein the multiple scale factors include at least one scale factor representing a sensitivity of each of multiple TRF combinations to each defect profile.

17. The system of claim 16 , wherein said deriving includes:
calculating a standard deviation of total thickness estimates for each possible defect profile; and
combining the total thickness estimates for the defect profile having a smallest standard deviation.

18. The system of claim 16 , wherein said deriving includes:
calculating a standard deviation of total thickness estimates for each single-pipe defect profile; and
selecting a minimum of the total thickness estimates for the single-pipe defect profile having a smallest standard deviation.

19. The system of claim 10 , the scale factors represent an average sensitivity of the phase difference for the associated TRF combination to a defect size

Assignees

• Halliburton Energy Services Inc

Inventors

• Guner Baris
• Donderici Burkay
• Amineh Reza K
• Fouda Ahmed E

Classifications

• G01N27/904 Primary

  with two or more sensors · CPC title

• G01V3/30

  operating with electromagnetic waves · CPC title

• G01V3/28

  using induction coils · CPC title

• E21B47/092

  by detecting magnetic anomalies · CPC title

• G01B7/10 Primary

  using magnetic means, e.g. by measuring change of reluctance · CPC title