Abstract: Embodiments provide for a method that utilizes the azimuthally spaced receivers of a sonic logging tool. Signals from monopole and dipole sources are reflected from the geologic interfaces and recorded by arrays of receivers of the same tool. For the incident P-waves from the monopole source, phase arrival times for the azimuthal receivers are compensated for stacking using properties of wave propagation in the borehole, and for the incident SH-waves from the dipole source, signs of waveforms for the receivers are changed for specified azimuths.

Abstract: A method for imaging one or more dipping structures is provided. The method comprises providing a given velocity model, calculating travel time of a seismic wave using the velocity model, estimating coherency of event signals of array data that are time-corrected for a trial reflector, weighting a waveform sample corresponding to the travel time based on the coherency, and mapping the weighted waveform sample.

Abstract: Seismic systems and processes for making and using same. In some examples, the seismic system can include an acoustic tool configured for placement in a wellbore penetrating a subterranean formation. The acoustic tool can include an acoustic transmitter unit for producing acoustic energy waveforms in the subterranean formation such that the interaction of the acoustic energy waveforms with structures in the formation can be an event that generates event signals. A receiver unit can include acoustic receivers distributed azimuthally around a central axis of the acoustic tool for sensing the event signals. The acoustic tool can determine event signal amplitudes of the event signals at each of the acoustic receivers, can determine which of the acoustic receivers has a maximum amplitude of the event signal amplitudes, and can interpolate between the maximum amplitude acoustic receiver and one or more adjacent acoustic receivers to find an azimuthal direction of the event.

Abstract: A method for wavefield separation of sonic data is provided. The method comprises estimating direct phases of waveforms of sonic data observed with two or more sensors by using cross-correlation of waveform traces at adjacent sensor locations, removing the direct phases from the observed waveforms, and extracting event signals from the waveforms after removing the direct phases.

Abstract: Event amplitudes associated with a reflector in a subterranean formation are estimated, wherein the events are detected by azimuthally distributed receivers of an acoustic tool in a wellbore penetrating the subterranean formation. The receiver closest to an azimuthal position of the reflector is identified based on the estimated event amplitudes. The azimuthal position of the reflector is determined using data obtained from (1) the receiver identified as closest to the azimuthal position of the reflector, and (2) two others of the receivers that are azimuthally adjacent the receiver identified as closest to the azimuthal position of the reflector.

Abstract: A technique facilitates improved data acquisition and analysis with downhole tools and systems. The downhole tools and systems utilize arrays of sensing devices which are deployed in arrangements for improved sensing of data related to environmental features and/or tool parameters of tools located downhole in a borehole. For example, the tools and sensing systems may be operated to effectively sense and store characteristics related to components of downhole tools as well as formation parameters at, for example, elevated temperatures and pressures. Similarly, chemicals and chemical properties of interest in oilfield exploration and development also may be detected, measured and stored for analysis.

Abstract: Seismic systems and processes for making and using same. In some examples, the seismic system can include an acoustic tool configured for placement in a wellbore penetrating a subterranean formation. The acoustic tool can include an acoustic transmitter unit for producing acoustic energy waveforms in the subterranean formation such that the interaction of the acoustic energy waveforms with structures in the formation can be an event that generates event signals. A receiver unit can include acoustic receivers distributed azimuthally around a central axis of the acoustic tool for sensing the event signals. The acoustic tool can determine event signal amplitudes of the event signals at each of the acoustic receivers, can determine which of the acoustic receivers has a maximum amplitude of the event signal amplitudes, and can interpolate between the maximum amplitude acoustic receiver and one or more adjacent acoustic receivers to find an azimuthal direction of the event.

Abstract: Event amplitudes associated with a reflector in a subterranean formation are estimated, wherein the events are detected by azimuthally distributed receivers of an acoustic tool in a wellbore penetrating the subterranean formation. The receiver is closest to an azimuthal position of the reflector is identified based on the estimated event amplitudes. The azimuthal position of the reflector is determined using data obtained from (1) the receiver identified as closest to the azimuthal position of the reflector, and (2) two others of the receivers that are azimuthally adjacent the receiver identified as closest to the azimuthal position of the reflector.

Abstract: A method for imaging one or more dipping structures is provided. The method comprises providing a given velocity model, calculating travel time of a seismic wave using the velocity model, estimating coherency of event signals of array data that are time-corrected for a trial reflector, weighting a waveform sample corresponding to the travel time based on the coherency, and mapping the weighted waveform sample.

Abstract: A method for wavefield separation of sonic data is provided. The method comprises estimating direct phases of waveforms of sonic data observed with two or more sensors by using cross-correlation of waveform traces at adjacent sensor locations, removing the direct phases from the observed waveforms, and extracting event signals from the waveforms after removing the direct phases.

Abstract: A technique facilitates improved data acquisition and analysis with downhole tools and systems. The downhole tools and systems utilize arrays of sensing devices which are deployed in arrangements for improved sensing of data related to environmental features and/or tool parameters of tools located downhole in a borehole. For example, the tools and sensing systems may be operated to effectively sense and store characteristics related to components of downhole tools as well as formation parameters at, for example, elevated temperatures and pressures. Similarly, chemicals and chemical properties of interest in oilfield exploration and development also may be detected, measured and stored for analysis.

Abstract: Methods of and apparatus to image one or more subsurface formation features are disclosed. An example method includes generating acoustic waves with a transmitter and receiving the acoustic waves and acoustic data contained therein at one or more receivers. The example method also includes extracting one or more S-S, P-S or S-P reflected waveform data from the acoustic data, estimating a dip of the one or more subsurface formation features, migrating the one or more S-S, P-S or S-P reflected waveform data with the estimated dip and mapping the migrated one or more S-S, P-S or S-P reflected waveform data. In addition, the example method includes identifying one or more permeable subsurface formation features using the mapped migrated one or more S-S, P-S or S-P reflected waveform data.

Abstract: Methods and systems for location and/or direction of a hypocenter. The methods may involve one or more of: a) computing a joint probability density function (PDF) which includes polarization PDF and onset time PDF or a time integral of product of detection transforms to estimate the location and/or direction of a hypocenter, where the polarization PDF is generated using a weighted average of differences between measured and computed polarizations; b) computing a time integral of product of modified detection transforms associated with onset times from received data in Coalescence Microsesimic Mapping where modified detection transform is defined as (?, fd(t)?1); c) resolving 180 degree ambiguities in polarization estimated according to Hodogram; d) using polynomial interpolation to tune the location of a hypocenter; and e) computing an integration time interval of 4-D (t,x,y,z) PDF or product of modified detection transform and the restriction on grid nodes.

Abstract: Methods and systems for processing acoustic measurements related to subterranean formations. The methods and systems provide receiving acoustic waveforms with a plurality of receivers, deriving slowness of the formation based on the acoustic waveforms, and modeling dominant waveforms in the acoustic waveforms based on the formation slowness, wherein deriving the formation slowness comprises parametric inversion for complex and frequency dependent slowness and the derived complex slowness has real and imaginary parts.

Abstract: A stiffness matrix H? is designed as PiTCPi or a linear combination form thereof, where a spatial first-order difference operator, which operates on a state vector, of a displacement vector at each discrete grid point is Pi and the matrix of elastic constants is C. The mass matrix T? is derived using finite-difference approximations at the discrete grid points so that the result of the matrix ?Tnum operating on a state vector corresponding to rotations or translations is 0, where T is a positive definite diagonal mass matrix and ?Tnum=T??T.

Abstract: Methods of and apparatus to image one or more subsurface formation features are disclosed. An example method includes generating acoustic waves with a transmitter and receiving the acoustic waves and acoustic data contained therein at one or more receivers. The example method also includes extracting one or more S-S, P-S or S-P reflected waveform data from the acoustic data, estimating a dip of the one or more subsurface formation features, migrating the one or more S-S, P-S or S-P reflected waveform data with the estimated dip and mapping the migrated one or more S-S, P-S or S-P reflected waveform data. In addition, the example method includes identifying one or more permeable subsurface formation features using the mapped migrated one or more S-S, P-S or S-P reflected waveform data.

Abstract: A stiffness matrix H? is designed as PiTCPi or a linear combination form thereof, where a spatial first-order difference operator, which operates on a state vector, of a displacement vector at each discrete grid point is Pi and the matrix of elastic constants is C. The mass matrix T? is derived using finite-difference approximations at the discrete grid points so that the result of the matrix 8Tnum operating on a state vector corresponding to rotations or translations is 0, where T is a positive definite diagonal mass matrix and ?Tnum=T??T.

Abstract: Methods and systems for processing acoustic measurements related to subterranean formations. The methods and systems provide receiving acoustic waveforms with a plurality of receivers, deriving slowness of the formation based on the acoustic waveforms, and modeling dominant waveforms in the acoustic waveforms based on the formation slowness, wherein deriving the formation slowness comprises parametric inversion for complex and frequency dependent slowness and the derived complex slowness has real and imaginary parts.

Abstract: Methods and related systems are described for measuring and analyzing refracted acoustic energy. A plurality of receivers mounted are on a downhole tool, and are arranged and adapted to receive refracted acoustic energy from a downhole formation. Measurements of refracted acoustic energy is analyzed such that information relating to an azimuthal direction relative to the downhole tool of an interface within the downhole formation can be estimated. The receivers can be mounted on a drill collar as part of a LWD tool and steering of the drilling trajectory can be based in part on the estimated formation information.