Characterization system and method for cement evaluation through-tubing

Abstract

In at least one embodiment, a well inspection method and system is disclosed. The method includes receiving signals from a casing structure using a well inspection tool, performing a Fast Fourier Transform (FFT) on the signals to generate spectrogram data, determining entropy spectra from the spectrogram data, performing component analysis based at least in part on the entropy spectra to select a subset of the entropy spectra, and determining casing loadings or cement bonding associated with the casing structure based at least in part on a subset of the entropy spectra.

What is claimed is: 
     
         1 . A well inspection method, comprising:
 receiving signals from a casing structure using a well inspection tool;   performing, using at least one processor associated with the well inspection tool, a Fast Fourier Transform (FFT) on the signals to generate spectrogram data;   determining entropy spectra from the spectrogram data;   performing a component analysis based at least in part on the entropy spectra to select a subset of the entropy spectra; and   determining casing loadings or cement bonding associated with the casing structure based at least in part on the subset of the entropy spectra.   
     
     
         2 . The well inspection method of  claim 1 , further comprising:
 determining a covariance matrix from the entropy spectra;   performing the component analysis to extract feature components from the entropy spectra;   determining scores of the feature components of the entropy spectra, wherein scores are associated with a depth and a sector within a well where the signals are received;   selecting individual ones of the scores for which underlying ones of the feature components are to be associated together to be within a dataset; and   performing clustering within the dataset to identify at least a cluster for the subset of the feature components, the cluster being associated with the casing loadings or cement bonding of the casing structure.   
     
     
         3 . The well inspection method of  claim 2 , wherein the feature components comprise one or more of bonding conditions of different actual or test casing or of different entropy spectra of different sectors that are at one or more depths in an actual or test well. 
     
     
         4 . The well inspection method of  claim 2 , further comprising:
 determining the covariance matrix from a first part of the entropy spectra that is sampled from the entropy spectra; and   validating the first part of the entropy spectra with a second part of the entropy spectra based in part on the feature components.   
     
     
         5 . The well inspection method of  claim 1 , further comprising:
 providing the well inspection tool as part of a production tubing, the production tubing being internally within the casing structure, wherein the casing loadings or cement bonding are associated with cement located externally relative to the casing structure.   
     
     
         6 . The well inspection method of  claim 1 , further comprising:
 providing the well inspection tool internally within the casing structure, wherein the casing loadings or cement bonding are associated with cement located externally relative to the casing structure.   
     
     
         7 . The well inspection method of  claim 1 , further comprising:
 enabling the well inspection tool to comprise a transmitter and at least one receiver in a pitch-catch or pulse-echo configuration;   transmitting, using the transmitter, a test signal from different circumferential positions of the well inspection tool towards walls of the casing structure; and   receiving, using the at least one receiver, the signals that are associated with the test signal, wherein the signals travel in a perpendicular direction relative to an axis of the casing structure or travel along an axial direction relative to the axis of the casing structure.   
     
     
         8 . The well inspection method of  claim 1 , further comprising:
 determining a power spectrum for at least one of the signals;   determining a sum of the power spectrum;   normalizing the power spectrum using the sum of the power spectrum; and   determining the entropy spectra based in part on a natural logarithm of the normalized power spectrum.   
     
     
         9 . The well inspection method of  claim 1 , wherein the casing loadings comprise one of a flow path condition or different material loadings. 
     
     
         10 . The well inspection method of  claim 1 , further comprising:
 providing the well inspection tool internally within a production tubing, the production tubing being internally within the casing structure, wherein a media is provided within the production tubing and within an annular space of the casing structure and the production tubing.   
     
     
         11 . A system for well inspection, comprising:
 a transmitter of a well inspection tool to transmit a test signal into a casing structure;   one or more receivers of the well inspection tool to receive signals from the casing structure to the well inspection tool; and   at least one processor and memory comprising instructions that when executed by the at least one processor enable the system to:
 perform a Fast Fourier Transform (FFT) on the signals to generate spectrogram data; 
 determine entropy spectra from the spectrogram data; 
 perform a component analysis based at least in part on the entropy spectra to select a subset of the entropy spectra; and 
 determine casing loadings or cement bonding associated with the casing structure based at least in part on the subset of the entropy spectra. 
   
     
     
         12 . The system of  claim 11 , wherein the memory comprising the instructions that when executed by the at least one processor further cause the system to:
 determine a covariance matrix from the entropy spectra;   perform the component analysis to extract feature components from the entropy spectra;   determine scores of the feature components of the entropy spectra, wherein scores are associated with a depth and a sector within a well where the signals are received;   select individual ones of the scores for which underlying ones of the feature components are to be associated together to be within a dataset; and   perform clustering within the dataset to identify at least a cluster for the subset of the feature components, the cluster being associated with the casing loadings or cement bonding of the casing structure.   
     
     
         13 . The system of  claim 12 , wherein the feature components comprise one or more of bonding conditions of different actual or test casing or of different entropy spectra of different sectors that are at one or more depths in an actual or test well. 
     
     
         14 . The system of  claim 12 , wherein the memory comprising the instructions that when executed by the at least one processor further cause the system to:
 determine the covariance matrix from a first part of the entropy spectra that is sampled from the entropy spectra; and   validate the first part of the entropy spectra with a second part of the entropy spectra based in part on the feature components.   
     
     
         15 . The system of  claim 11 , wherein the well inspection tool is part of a production tubing, the production tubing being internally within the casing structure, wherein the casing loadings or cement bonding are associated with cement located externally relative to the casing structure. 
     
     
         16 . The system of  claim 11 , wherein the well inspection tool is to be internally within the casing structure, wherein the casing loadings or cement bonding are associated with cement located externally relative to the casing structure. 
     
     
         17 . The system of  claim 11 , wherein the well inspection tool comprises the transmitter and the one or more receivers in a pitch-catch or pulse-echo configuration. 
     
     
         18 . The system of  claim 11 , wherein the test signal is transmitted from different circumferential positions of the well inspection tool towards walls of the casing structure, and wherein the signals received are associated with the test signal, wherein the signals travel in a perpendicular direction relative to an axis of the casing structure or travel along an axial direction relative to the axis of the casing structure. 
     
     
         19 . The system of  claim 11 , wherein the memory comprising the instructions that when executed by the at least one processor further cause the system to:
 determine a power spectrum for at least one of the return signals;   determine a sum of the power spectrum;   normalize the power spectrum using the sum of the power spectrum; and   determine the entropy spectra based in part on a natural logarithm of the normalized power spectrum.   
     
     
         20 . The system of  claim 11 , wherein the well inspection tool is to be internally within a production tubing, the production tubing to be internally within the casing structure, wherein a media is to be within the production tubing and within an annular space of the casing structure and the production tubing.