Ultrasonic casing and cement evaluation method using a ray tracing model

Patent metadata

Field	Value
Publication number	US-2016265348-A2
Application number	US-201414417439-A
Country	US
Kind code	A2
Filing date	Jul 15, 2014
Priority date	Aug 15, 2013
Publication date	Sep 15, 2016
Grant date	—

Abstract

Systems, methods, and software for determining impedance of a casing-cement bond are described. In some aspects, the bond impedance is determined based on results of comparing a measured waveform and a model waveform. The model waveform corresponds to an estimated impedance of the bond and corresponds to a ray tracing of an acoustic signal that accounts for a radiation pattern of the acoustic transmitter and a curvature of the well casing. The measured waveform and the model waveform are generated based on operating an acoustic transmitter and an acoustic receiver within a wellbore comprising the well casing.

First claim

What is claimed is:

1 . A method comprising:
accessing a measured waveform associated with an acoustic signal returned via a well casing based on operating an acoustic transmitter and an acoustic receiver within a wellbore comprising the well casing; comparing the measured waveform to a model waveform, wherein the model waveform corresponds to an estimated impedance of a medium surrounding an exterior portion of the well casing, and the model waveform corresponds to a ray tracing of the acoustic signal that accounts for a radiation pattern of the acoustic transmitter and a curvature of the well casing; and determining, by operation of data processing apparatus, an impedance of the medium surrounding the exterior portion of the well casing based on results of comparing the measured waveform to the model waveform.

2 . The method of claim 1 , further comprising:
decomposing an acoustic signal emitted from the acoustic transmitter into a plurality of rays; calculating characteristics of each of the plurality of rays based on the radiation pattern of the acoustic transmitter and the curvature of the well casing; determining a subset of the plurality of rays that are returned via the well casing and detected by the acoustic receiver; and combining the characteristics of the subset of the plurality of rays to generate the model waveform.

3 . The method of claim 1 , wherein:
comparing the measured waveform to the model waveform comprises comparing differences between the measured waveform and the model waveform; and determining the impedance of the medium comprises determining optimal fitting values for the impedance of the medium based on results of comparing the differences between the measured waveform and the model waveform.

4 . The method of claim 1 , wherein comparing the measured waveform to the model waveform comprises applying an inversion technique to compare the measured waveform and the model waveform.

5 . The method of claim 4 , wherein the inversion technique comprises a one-dimensional grid search.

6 . The method of claim 4 , wherein the inversion technique comprises a generalized linear inversion.

7 . The method of claim 4 , wherein the inversion technique comprises a non-linear inversion.

8 . The method of claim 1 , wherein determining the impedance of the medium comprises determining the impedance of the medium in real time during drilling operations or wireline logging operations.

9 . A non-transitory computer-readable medium encoded with instructions that, when executed by data processing apparatus, cause the data processing apparatus to perform operations comprising:
accessing a measured waveform associated with an acoustic signal returned via a well casing based on operating an acoustic transmitter and an acoustic receiver within a wellbore comprising the well casing; comparing the measured waveform to a model waveform, wherein the model waveform corresponds to an estimated impedance of a medium surrounding an exterior portion of the well casing, and the model waveform corresponds to a ray tracing of the acoustic signal that accounts for a radiation pattern of the acoustic transmitter and a curvature of the well casing; and determining an impedance of the medium surrounding the exterior portion of the well casing based on results of comparing the measured waveform to the model waveform.

10 . The non-transitory computer-readable medium of claim 9 , wherein the operations further comprise:
decomposing an acoustic signal emitted from the acoustic transmitter into a plurality of rays; calculating characteristics of each of the plurality of rays based on the radiation pattern of the acoustic transmitter and the curvature of the well casing; determining a subset of the plurality of rays that are returned via the well casing and detected by the acoustic receiver; and combining the characteristics of the subset of the plurality of rays to generate the model waveform.

11 . The non-transitory computer-readable medium of claim 9 , wherein:
comparing the measured waveform to the model waveform comprises comparing differences between the measured waveform and the model waveform; and determining the impedance of the medium comprises determining optimal fitting values for the impedance of the medium based on results of comparing the differences between the measured waveform and the model waveform.

12 . The non-transitory computer-readable medium of claim 9 , wherein comparing the measured waveform to the model waveform comprises applying an inversion technique to compare the measured waveform and the model waveform.

13 . The non-transitory computer-readable medium of claim 12 , wherein the inversion technique comprises a one-dimensional grid search.

14 . The non-transitory computer-readable medium of claim 12 , wherein the inversion technique comprises a generalized linear inversion.

15 . The non-transitory computer-readable medium of claim 12 , wherein the inversion technique comprises a non-linear inversion.

16 . The non-transitory computer-readable medium of claim 9 , wherein determining the impedance of the medium comprises determining the impedance of the medium in real time during drilling operations or wireline logging operations.

17 . A system comprising:
an acoustic transmitter-receiver pair to be disposed within a wellbore comprising a well casing; and a computing system coupled with the acoustic transmitter-receiver pair, the computing system is configured to:
access a measured waveform associated with an acoustic signal returned via a well casing based on operating an acoustic transmitter and an acoustic receiver within an interior portion of the well casing;
compare the measured waveform to a model waveform, wherein the model waveform corresponds to an estimated impedance of a medium surrounding an exterior portion of the well casing, and the model waveform corresponds to a ray tracing of the acoustic signal that accounts for a radiation pattern of the acoustic transmitter and a curvature of the well casing; and
determine an impedance of the medium surrounding the exterior portion of the well casing based on results of comparing the measured waveform to the model waveform.

18 . The system of claim 17 , wherein the computing system is configured to:
decompose an acoustic signal emitted from the acoustic transmitter into a plurality of rays; calculate characteristics of each of the plurality of rays based on the radiation pattern of the acoustic transmitter and the curvature of the well casing; determine a subset of the plurality of rays that are returned via the well casing and detected by the acoustic receiver; and combine the characteristics of the subset of the plurality of rays to generate the model waveform.

19 . The system of claim 17 , wherein:
the computing system is configured to compare the measured waveform to the model waveform comprises the computing system is configured to compare differences between the measured waveform and the model waveform; and the computing system is configured to determine the impedance of the medium comprises the computing system is configured to determine optimal fitting values for the impedance of the medium based on results of comparing the differences between the measured waveform and the model waveform.

20 . The system of claim 17 , wherein the computing system is configured to compare the measured waveform to the model waveform comprises the computing system is configured to apply an

Assignees

• Halliburton Energy Services Inc

Inventors

• Chen Tianrun
• Zheng Yibing
• Gilstrap Tatiana
• Cheng Arthur Chuen Hon
• Epstein Robert Eric
• Zhang Zhijuan

Classifications

• E21B47/16 Primary

  through the drill string or casing {, e.g. by torsional acoustic waves} · CPC title

• E21B47/00

  Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B21/08) · CPC title

• E21B47/005 Primary

  Monitoring or checking of cementation quality or level · CPC title

• G01V1/40

  specially adapted for well-logging · CPC title