Methods for processing sonic data

Claim 1

A method of sonic logging comprising the steps of: establishing at a depth of interest in a borehole a set of peak matrices comprised of peak vectors representative of a plurality of different characteristics of sonic signals traversing an earth formation, establishing a set of rules based upon borehole sonic characteristics and including the utilization of past histories of slowness and coherence values of wave components of interest, searching said matrices in accordance with said rules to identify the presence in said sonic signals of wave components of interest, recording those identified wave components as a function of the depth of interest, and repeating said steps at each depth of interest; in which said peak vectors include the characteristics of the maximum of peak coherence and the energy associated with the maximum of peak coherence for each wave component and the wave components include a compressional component, a shear wave component a casing peak and a Stoneley wave compohent; and further in which a casing peak is identified by counting over a given number of waveform sets the number of peaks with slowness within a given slowness range and whose arrival times are within a predetermined amount of the integrated casing time and having a coherence value greater than a given coherence cut, upon counting more than one peak, searching for the peak within the given casing slowness range having the maximum coherence value and identifying it as the casing peak.

Claim 2

A method of sonic logging comprising the steps of: establishing at a depth of interest in a borehole a set of peak matrices comprised of peak vectors representative of a plurality of different characteristics of sonic signals traversing an earth formation, establishing a set of rules based upon borehole sonic characteristics and including the utilization of past histories of slowness and coherence values of wave components of interest, searching said matrices in accordance with said rules to identify the presence in said sonic signals of wave components of interest, recording those identified wave components as a function of the depth of interest, and repeating said steps at each depth of interest; in which said peak vectors include the characteristics of the maximum of peak coherence and the energy associated with the maximum of peak coherence for each wave component and the wave components include a compressional component, a shear wave component a casing peak and a Stoneley wave compohent; and further in which a casing peak is identified by counting over a given number of waveform sets the number of peaks with slowness within a given slowness range and whose arrival times are within a predetermined amount of the integrated casing time and having a coherence value greater than a given coherence cut, upon counting more than one peak, searching for the peak within the given casing slowness range having the maximum coherence value and identifying it as the casing peak.

Claim 6

A method of sonic logging comprising the steps of: deriving sonic logs representing the receipt of successive borehole depth levels, of sonic signals by receivers which are spaced along the length of a borehole sonde from each other and from at least one transmitter of the sonic signals, converting the sonic logs to peaks at the succession of borehole depth levels, of the coherence measure for the energy in the sonic signals, converting the sonic logs to peaks at the succession of borehole depth levels, of the coherence measure for the energy in the sonic signals, searching the peaks in accordance with criteria based upon borehole acoustics, sonde response and past history of coherence measure to identify compressional, shear and Stoneley components, and recording the identified components as a function of depth; and in which the compressional arrival is determined by selecting the peaks with slowness within a given compressional range and having a coherence value greater than a given coherence-cut for compressional to form a subgroup, screening the subgroup to delete those peaks whose time of arrival deviate from an integrated compressional time by more than a predetermined amount, and selecting the peak having a minimum arrival time as the compressional arrival.

Claim 7

A method of sonic logging comprising the steps of: deriving sonic logs representing the receipt of successive borehole depth levels, of sonic signals by receivers which are spaced along the length of a borehole sonde from each other and from at least one transmitter of the sonic signals, converting the sonic logs to peaks at the succession of borehole depth levels, of the coherence measure for the energy in the sonic signals, converting the sonic logs to peaks at the succession of borehole depth levels, of the coherence measure for the energy in the sonic signals, searching the peaks in accordance with criteria based upon borehole acoustics, sonde response and past history of coherence measure to identify compressional, shear and Stoneley components, and recording the identified components as a function of depth; and in which the compressional arrival is determined by selecting the peaks with slowness within a given compressional range and having a coherence value greater than a given coherence-cut for compressional to form a subgroup, screening the subgroup to delete those peaks whose time of arrival deviate from an integrated compressional time by more than a predetermined amount, and selecting the peak having a minimum arrival time as the compressional arrival.

Claim 8

A method of sonic logging comprising the steps of: deriving sonic logs representing the receipt at successive borehole depth levels, of sonic signals by receivers which are spaced along the length of a borehole sonde from each other and from at least one transmitter of the sonic signals, converting the sonic logs to peaks at the succession of borehole depth levels, of the coherence measure for the energy in the sonic signals, searching the peaks in accordance with criteria based upon borehole acoustics, sonde response and past history of coherence measure to identify compressional, shear and Stonely components, and recording the identified components as a function of depth; and further in which the compressional arrival is determined by selecting from the peaks that peak having maximum coherence with slowness within a slowness range determined dynamically based upon the past history of compressional peak slowness, whose arrival time is within a predetermined amount of the integrated compressional time and is possessed of a coherence value greater than a given coherence cut for compressional.

Claim 9

A method of sonic logging comprising the steps of: deriving sonic logs representing the receipt at successive borehole depth levels, of sonic signals by receivers which are spaced along the length of a borehole sonde from each other and from at least one transmitter of the sonic signals, converting the sonic logs to peaks at the succession of borehole depth levels, of the coherence measure for the energy in the sonic signals, searching the peaks in accordance with criteria based upon borehole acoustics, sonde response and past history of coherence measure to identify compressional, shear and Stonely components, and recording the identified components as a function of depth; and further in which the compressional arrival is determined by selecting from the peaks that peak having maximum coherence with slowness within a slowness range determined dynamically based upon the past history of compressional peak slowness, whose arrival time is within a predetermined amount of the integrated compressional time and is possessed of a coherence value greater than a given coherence cut for compressional.

Claim 10

A method of sonic logging comprising the steps of: deriving sonic logs representing the receipt at successive borehole depth levels, of sonic signals by receivers which are spaced along the length of a borehole sonde from each other and from at least one transmitter of the sonic signals, converting the sonic logs to peaks at the succession of borehole depth levels, of the coherence measure for the energy in he sonic signals, searching the peaks in accordance with criteria based upon borehole acoustics, sonde response and past history of coherence measure to identify compressional, shear and Stonely components, and recording the identified components as a function of depth; and further in which the compressional arrival is determined by seeking a first candidate as the compressional arrival through a procedure of selecting the peaks with slowness within a given compressional range and having a coherence value greater than a given coherence-cut for compressional to form a subgroup, screening the subgroup to delete those peaks whose time of arrival deviate from an integrated compressional time by more than a predetermined amount, selecting the peak having a minimum arrival time as the first candidate for compressional arrival, seeking a second candidate as the compressional arrival by searching from among the peaks for a peak having maximum coherence with slowness within a slowness range determined dynamically based upon the past history of the compressional peak slowness, whose arrival time is within a predetermined amount of the integrated compressional time and is possessed of a coherence value greater than a given coherence-cut for compressional, upon the existence of both candidates, selecting the candidate with the higher coherence peak as the compressional peak.

Claim 11

A method of sonic logging comprising the steps of: deriving sonic logs representing the receipt at successive borehole depth levels, of sonic signals by receivers which are spaced along the length of a borehole sonde from each other and from at least one transmitter of the sonic signals, converting the sonic logs to peaks at the succession of borehole depth levels, of the coherence measure for the energy in he sonic signals, searching the peaks in accordance with criteria based upon borehole acoustics, sonde response and past history of coherence measure to identify compressional, shear and Stonely components, and recording the identified components as a function of depth; and further in which the compressional arrival is determined by seeking a first candidate as the compressional arrival through a procedure of selecting the peaks with slowness within a given compressional range and having a coherence value greater than a given coherence-cut for compressional to form a subgroup, screening the subgroup to delete those peaks whose time of arrival deviate from an integrated compressional time by more than a predetermined amount, selecting the peak having a minimum arrival time as the first candidate for compressional arrival, seeking a second candidate as the compressional arrival by searching from among the peaks for a peak having maximum coherence with slowness within a slowness range determined dynamically based upon the past history of the compressional peak slowness, whose arrival time is within a predetermined amount of the integrated compressional time and is possessed of a coherence value greater than a given coherence-cut for compressional, upon the existence of both candidates, selecting the candidate with the higher coherence peak as the compressional peak.

Claim 13

A method of sonic logging comprising the steps of: deriving sonic logs representing the receipt at successive borehole depth levels, of sonic signals by receivers which are spaced along the length of a borehole sonde from each other and from at least one transmitter of the sonic signals, converting the sonic logs to peaks at the succession of borehole depth levels, of the coherence measure for the energy in the sonic signals, searching the peaks in accordance with criteria based upon borehole acoustics, sonde response and past history of coherence measure to identify compressional, shear and Stoneley components, and recording the identified components as a function of depth; and in which the Stoneley arrival is dtermined by selecting a subgroup of peaks having slowness larger than a given fluid slowness and a coherence value higher than a coherence-cut for Stoneley waves, screening the subgroup to delete peaks having arrival times deviating from an integrated Stoneley arrival time by a predetermined amount, and selecting from the remaining peaks the peak having the highest energy as representative of Stoneley arrival.

Claim 14

A method of sonic logging comprising the steps of: deriving sonic logs representing the receipt at successive borehole depth levels, of sonic signals by receivers which are spaced along the length of a borehole sonde from each other and from at least one transmitter of the sonic signals, converting the sonic logs to peaks at the succession of borehole depth levels, of the coherence measure for the energy in the sonic signals, searching the peaks in accordance with criteria based upon borehole acoustics, sonde response and past history of coherence measure to identify compressional, shear and Stoneley components, and recording the identified components as a function of depth; and in which the Stoneley arrival is dtermined by selecting a subgroup of peaks having slowness larger than a given fluid slowness and a coherence value higher than a coherence-cut for Stoneley waves, screening the subgroup to delete peaks having arrival times deviating from an integrated Stoneley arrival time by a predetermined amount, and selecting from the remaining peaks the peak having the highest energy as representative of Stoneley arrival.