Systems and methods for data driven parametric correction of acoustic cement evaluation data

Patent metadata

Field	Value
Publication number	US-10401522-B2
Application number	US-201414891421-A
Country	US
Kind code	B2
Filing date	May 16, 2014
Priority date	May 16, 2013
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

Systems, methods, and devices for evaluating proper cement installation in a well are provided. In one example, a method includes receiving acoustic cement evaluation data parameterized using a first parameterization. A subset of the acoustic cement evaluation data is compared to expected nominal values of the acoustic cement evaluation data. When the subset of the acoustic cement evaluation data does not substantially conform to the expected nominal values of the acoustic cement evaluation data, all or part of the acoustic cement evaluation data is corrected to cause the subset of the acoustic cement evaluation data to more closely match the expected nominal values of the acoustic cement evaluation data. The corrected acoustic cement evaluation data may be used to estimate a presence of solids, liquids, and/or gases behind the casing.

First claim

The invention claimed is:

1. A method comprising:
obtaining acoustic cement evaluation data with an acoustic logging tool used in a well having a casing, wherein the acoustic cement evaluation data comprises flexural attenuation data and first acoustic impedance data and wherein the acoustic cement evaluation data has been parameterized using a first parameterization;
receiving the acoustic cement evaluation data into a data processing system;
comparing a subset of the acoustic cement evaluation data to expected nominal values of the acoustic cement evaluation data, wherein all of the subset of the acoustic cement evaluation data that is compared to the expected nominal values is beneath an evanescence point;
when the subset of the acoustic cement evaluation data does not substantially conform to the expected nominal values of the acoustic cement evaluation data, correcting all or part of the acoustic cement evaluation data to cause the subset of the acoustic cement evaluation data to more closely match the expected nominal values of the acoustic cement evaluation data; and
using the corrected acoustic cement evaluation data to estimate a presence of solids, liquids, or gases, or any combination thereof, behind the casing.

2. The method of claim 1 , wherein the first parameterization comprises a first flexural attenuation calibration, a first expected well fluid acoustic impedance, or a combination thereof, and wherein a second parameterization comprises a second flexural attenuation calibration, a second expected well fluid acoustic impedance, or a combination thereof.

3. The method of claim 1 , comprising:
transforming the flexural attenuation data into second acoustic impedance data; and
determining a first x-y density distribution using at least part of the first and second acoustic impedance data corresponding to the subset of the cement evaluation data, wherein the subset of the cement evaluation data comprises no data points above an evanescence point;
wherein comparing the subset of the acoustic cement evaluation data to the expected nominal values of the acoustic cement evaluation data comprises comparing the first x-y density distribution to expected nominal values of an expected x-y acoustic cement evaluation density distribution.

4. The method of claim 3 , wherein comparing the subset of the acoustic cement evaluation data to the expected nominal values of the acoustic cement evaluation data comprises:
identifying local maxima or centroids, or both, of data points of the first x-y density distribution; and
determining one or more criteria, wherein the criteria are one or more of the following:
whether the data points of the first x-y density distribution are substantially distributed along a unit slope;
whether a range of the data points of the first x-y density distribution substantially occurs over an expected range associated with a solid-liquid-gas map;
whether the local maxima or centroids, or both, occur substantially equally along both the x and y axes; or
whether the local maxima or centroids, or both, occur substantially at expected nominal anchor points;

wherein the subset of the acoustic cement evaluation data is considered not to substantially conform to the expected nominal values of the cement evaluation data when the above criteria are not substantially met.

5. The method of claim 1 , wherein correcting the acoustic cement evaluation data comprises:
reprocessing the acoustic cement evaluation data using a second parameterization different from the first parameterization to obtain a second x-y density distribution;
for data points below an evanescence point, determining one or more criteria, wherein the criteria are one or more of the following:
whether data points of the second x-y density distribution are substantially distributed in a unit slope;
whether local maxima or centroids, or both, of the second x-y density distribution occur substantially equally along both the x and y axes; or
whether the local maxima or centroids, or both, of the second x-y density distribution occur substantially at expected nominal anchor points;
and

re-parameterizing the acoustic cement evaluation data using the second parameterization instead of the first parameterization unless the above criteria are not substantially met.

6. The method of claim 1 , wherein correcting the acoustic cement evaluation data comprises:
implementing offsets directly to the data points of the first x-y density distribution to obtain a second x-y density distribution;
for data points below an evanescence point, determining criteria of at least one of the following:
whether data points of the second x-y density distribution are substantially distributed in a unit slope; or
whether local maxima or centroids, or both, of the second x-y density distribution occur substantially equally along both the x and y axes; or
whether the local maxima or centroids, or both, of the second x-y density distribution occur substantially at expected nominal anchor points; and

applying the offsets to the acoustic cement evaluation data unless the above criteria are not substantially met.

7. The method of claim 1 , wherein the acoustic cement evaluation data comprises either first acoustic impedance data or flexural attenuation data, but not both.

8. The method of claim 7 , comprising determining a single-measurement density distribution using the acoustic cement evaluation data, wherein comparing the subset of the acoustic cement evaluation data to the expected nominal values of the acoustic cement evaluation data comprises comparing the single-measurement density distribution to expected nominal values of an expected single-measurement acoustic cement evaluation density distribution.

9. The method of claim 8 , wherein correcting the acoustic cement evaluation data comprises:
reprocessing the acoustic cement evaluation data using a second parameterization different from the first parameterization to obtain a second single-measurement density distribution;
determining criteria of whether local maxima of the second single-measurement density distribution occur substantially at expected nominal anchor points of the expected single-measurement acoustic cement evaluation density distribution; and
re-parameterizing the acoustic cement evaluation data using the second parameterization instead of the first parameterization unless the above criteria are not substantially met.

10. The method of claim 8 , wherein correcting the acoustic cement evaluation data comprises:
implementing offsets directly to data points of the first single-measurement density distribution to obtain a second single-measurement density distribution;
determining criteria of whether local maxima of the second single-measurement density distribution occur substantially at expected nominal anchor points of the expected single-measurement acoustic cement evaluation density distribution; and
applying the offsets to the acoustic cement evaluation data unless the above criteria are not substantially met.

11. One or more non-transitory, tangible computer-readable media storing instructions to:
receive acoustic measurements having a first parameterization and obtained by one or more acoustic tools over a depth interval of a well; wherein the acoustic cement evaluation data comprises flexural attenuation data and first acoustic impedance data;
analyze a subset of the acoustic measurements beneath an acoustic impedance evanescence point; wherein all of the subset of the acoustic cement evaluation data that is compared to the expected nominal values is beneath an evanescence point;
estimate a correction to the acoustic measurements

Assignees

• Schlumberger Technology Corp

Inventors

• Van Kuijk Robert
• Kalyanaraman Ram Sunder

Classifications

• G01V1/48 Primary

  Processing data · CPC title

• E21B47/0005

  Fixed Constructions · mapped topic

• E21B47/005 Primary

  Monitoring or checking of cementation quality or level · CPC title