Annular-A characterization for inner tubular eccentricity and wave propagation speed estimation
Determining eccentricity and its direction of an inner tubular (e.g., tubing, liner, inner casing, etc.) in a cased hole using pulse-echo signals that are acquired in, for example, a dual-string cased well, being pre-processed for enhancing echo signals from the outer annular boundary and for reducing the inner tubular specular echo and pipe ringing. Disclosed methods also provide propagation speeds, of the signals traversing the annular materials between the inner tubular and outer annular boundary, that is used to identify annular material (e.g., production fluids, brine, water, cement, collapsed formation, etc) and one of the input parameters for dual-string cement evaluation.
1 . A method for processing signals, comprising:
obtaining, by a pulse-echo tool conveyed in a borehole of a well, data for evaluation, wherein the pulse-echo tool comprises a tool face and at least one ultrasonic transducer rotating relative to the tool face, and wherein the data includes pulse-echo signals acquired at a plurality of circumferential positions of the borehole or at a plurality of acquisition azimuths of the borehole;
conducting a pre-processing evaluation of the data obtained to achieve a pre-processed data set by aligning the pulse-echo signals based on an inner tubular echo arrival time, wherein the pulse-echo signals are transmitted and received by the ultrasonic transducer;
determining a third interface echo arrival time for the pre-processed data set;
preparing at least one model-based delay profile of eccentricities in the pre-processed data set;
back-propagating the pre-processed data set according to each of the model-based delay profiles to compensate for an eccentricity-dependent delay of an outer casing echo and generate one or more back-delayed signals;
computing a coherence of back-delayed signals derived from the pre-processed data set for the at least one model-based delay profile;
selecting a delay profile providing a maximum coherence of data;
determining an absolute value of echo arrival time, at least at one evaluation azimuth of the selected delay profile;
determining a wave propagation velocity from the determined absolute value of echo arrival time and the at least at one evaluation azimuth of the selected delay profile;
determining an eccentricity based upon the determined wave propagation velocity; and
outputting at least one of the eccentricity or the wave propagation velocity for use in evaluating the borehole.
2 . The method according to claim 1 , wherein the data for evaluation further includes wellbore geometrical parameters.
3 . The method according to claim 2 , wherein conducting the pre-processing evaluation enhances features of the pulse-echo signals of the third interface echo and reduces features of the pulse-echo signals of the inner tubular.
4 . The method according to claim 2 , wherein a pulse-echo beam is formed to enhance features of the pulse-echo signals of the third interface echo with respect to features of the pulse-echo signals of the inner tubular.
5 . The method according to claim 1 , wherein numerical forward modeling is used in the method.
6 . The method according to claim 5 , wherein the numerical forward modeling is one of a ray-tracing analysis, finite element analysis, a finite difference analysis, a spectral element analysis, and a semi-analytical green function-based analysis.
7 . A method for processing ultrasonic-based signals for data preparation for eccentricity estimation, comprising:
extracting, by a pulse-echo tool conveyed in a cased wellbore, at least one pulse-echo signal, at least at one acquisition azimuth, and at least at one depth in the cased wellbore, wherein the pulse-echo tool comprises a tool face and at least one ultrasonic transducer rotating relative to the tool face;
determining an inner tubular echo signal envelope peak amplitude and a time providing a same feature of the echo signal, at least including a closest zero-crossing to a peak for each signal extracted;
aligning each of the extracted pulse-echo signals referring to the time of the same feature to achieve a pre-processed data set, wherein the pulse-echo signals are transmitted and received by the ultrasonic transducer;
normalizing each of the extracted pulse-echo signals using the envelope peak amplitude;
enhancing third interface echo signals by reducing the inner tubular specular echo and inner tubular ringing;
preparing at least one model-based delay profile of eccentricities in the pre-processed data set;
back-propagating the pre-processed data set according to each of the model-based delay profiles to compensate for an eccentricity-dependent delay of an outer casing echo and generate one or more back-delayed signals;
estimating pipe eccentricity data based on the enhanced third interface echo signals and the normalized pulse-echo signals, wherein the pipe eccentricity data includes at least one of an inner tubular eccentricity, an azimuthal direction and a wave propagation speed of annular material; and
outputting the estimated pipe eccentricity data for use in evaluating a borehole.
8 . The method for processing ultrasonic-based signals according to claim 7 , further comprising after outputting the estimated pipe eccentricity data, returning the extracting the pulse-echo signals in a cased wellbore at different depth and performing the method again.
9 . The method according to claim 7 , wherein extracting the at least one pulse-echo signal at the at least one depth in the wellbore includes performing a band-pass filtering to the signal to increase sensitivity to a resonance of the inner tubular.
10 . The method according to claim 7 , wherein the aligning of each of the extracted pulse-echo signals includes applying a time shift to each of the signals.
11 . The method according to claim 7 , wherein the method is performed at least in one of a single-string cased wellbore and a dual-string cased wellbore.
12 . The method according to claim 7 , wherein numerical forward modeling is used in the method, and wherein the numerical forward modeling is one of a ray-tracing analysis, a finite element analysis, a finite difference analysis, a spectral element analysis, and a semi-analytical green function-based analysis.
13 . An article of manufacture having a non-volatile memory, the non-volatile memory configured to store a list of instructions, the list of instructions comprising, at least in part, a method for processing signals that may be read and performed by a computing device, the method comprising:
obtaining, by a pulse-echo tool conveyed in a borehole of a well, data for evaluation, wherein the pulse-echo tool comprises a tool face and at least one ultrasonic transducer rotating relative to the tool face, and wherein the data includes pulse-echo signals acquired at a plurality of circumferential positions of the borehole or at a plurality of acquisition azimuths of the borehole;
conducting a pre-processing evaluation of the data obtained to achieve a pre-processed data set by aligning the pulse-echo signals based on an inner tubular echo arrival time, wherein the pulse-echo signals are transmitted and received by the ultrasonic transducer;
determining a third interface echo arrival time for the pre-processed data set;
preparing at least one model-based delay profile of eccentricities in the pre-processed data set;
back-propagating the pre-processed data set according to each of the model-based delay profiles to compensate for an eccentricity-dependent delay of an outer casing echo and generate one or more back-delayed signals;
computing a coherence of back-delayed signals derived from the pre-processed data set for the at least one model-based delay profile;
selecting a delay profile providing a maximum coherence of data;
determining an absolute value of echo arrival time, at least at one evaluation azimuth of the selected delay profile;
determining a wave propagation velocity from the determined absolute value of echo arrival time and the at least at one evaluation azimuth of the selected delay profile;
determining an eccentricity based upon the determined wave propagation velocity; and
outputting at least one of the eccentricity or the wave propagation velocity for use in evaluating the borehole.
14 . The article of manufacture according to claim 13 , wherein the article of manufacture is configured as one of a compact disk, a solid-state memory, a universal serial bus, and a computer hard disk.
15 . The article of manufacture according to claim 13 , wherein the method is performed such that conducting the pre-processing evaluation enhances features of the third interface echo.
16 . The article of manufacture according to claim 13 , wherein the method is performed such that a numerical forward modeling is used in the method.
17 . The article of manufacture according to claim 16 , wherein the method is performed such that the numerical forward modeling is one of a ray-tracing analysis, a finite element analysis, a finite difference analysis, a spectral element analysis, and a semi-analytical green function-based analysis.