Methods and systems, including computer programs encoded on a computer storage medium can be used for identifying primary-wave (P-wave) and secondary-wave (S-wave) characteristics of an underground formation by separating P-wave and S-wave modes of seismic data generated by applying a seismic source to a subterranean region of a geological area. Particle motion vectors of a P-wave are parallel to a propagation vector of the P-wave, whereas particle motion vectors of an S-wave are perpendicular to a propagation vector of the S-wave. The parallel and perpendicular relationship between the motion and propagation vectors of the respective P- and S-waves provide a basis for separating P- and S-wave components from a wavefield. The separation methodology extracts P-wave components and S-wave components from the wavefield based on an estimated angle between propagation vectors and wave motion vectors for the wavefield.

A sonic logging method is provided that transmits acoustic signals using a high order acoustic source and processes waveform data to identify a set of arrival events and time picks by automatic and/or manual methods. Ray tracing inversion is carried out for each arrival event over a number of possible raypath types that include at least one polarized shear raypath type to determine two-dimensional reflector positions and predicted inclination angles of the arrival event for the possible raypath types. One or more three-dimensional slowness-time coherence representations are generated for the arrival event and raypath type(s) and evaluated to determine azimuth, orientation and raypath type of a corresponding reflector. The method outputs a three-dimensional position and orientation for at least one reflector. The information derived from the method can be conveyed in various displays and plots and structured formats for reservoir understanding and also output for use in reservoir analysis and other applications.

Methods and systems including computer programs encoded on a computer storage medium, for utilizing equivalent linear velocity for first arrival picking of seismic refraction. In one aspect, a method includes receiving data for the shot gather record, generating a diving wave equation curve for a particular parameter pair of multiple parameter pairs, and integrating the shot gather record data corresponding to the diving wave equation curve over a selected range of offsets of the shot gather to generate an equivalent linear velocity value for the particular parameter pair and the shot gather record data, selecting, from the equivalent linear velocity values for the plurality of parameter pairs, a greatest equivalent linear velocity value of the equivalent linear velocity values, the greatest equivalent linear velocity value corresponding to a first-arrival parameter pair, and determining, using the first-arrival parameter pair, a set of first-arrival onsets for the selected sub-range of offsets.

A method for determining and tracking an edge of first breaks is provided. The method includes obtaining seismic data associated with subsurface formations, the seismic data relating to a vibration contacting a plurality of portions of the subsurface formations, processing the seismic data to produce processed seismic data comprising one or more attributes, wherein the processed seismic data defines an edge characterizing a plurality of onset times, iteratively performing, using a level sets algorithm, a plurality of tracking operations on the processed seismic data to identify the edge characterizing a plurality of first breaks' onset times, and determining the edge as first breaks.

A method, article and system are provided for processing and interpreting acoustic data. The method and system includes providing a number of acoustic processing elements, each element being associated with an acoustic mode of a number of acoustic modes of a sonic measurement tool adapted to acquire data representing acoustic measurements in a borehole. In addition the method and system includes providing a user interface to organize a processing chain of the number of acoustic processing elements such that the acoustic processing elements process the acquired data according to a predefined workflow.

The present invention provides a seismic signal processing method, device and system. The method comprises: obtaining an offset of a reflected seismic signal at a sampling point and the corresponding reflected wave arrival time; constructing a non-hyperbolic dynamic correction formula based on Pade approximation according to the offset of the reflected seismic signal at the sampling point and the corresponding reflected wave arrival time; extracting a vertical propagation velocity and anisotropy parameters of the reflected seismic signal according to the non-hyperbolic dynamic correction formula constructed based on Pade approximation.

A method for borehole measurements may comprise receiving one or more signals from a linear receiver array, computing an arctan of a Hilbert Transform, isolating a first arriving energy, selecting a reference instantaneous phase on a reference receiver, finding the reference instantaneous phase for the linear receiver array, computing a relative travel time shift, combining a reference pick time with a relative time, and determining a travel time. A system for borehole measurements comprise a conveyance, a bottom hole assembly attached to the conveyance, a linear receiver array, wherein the linear receiver array is disposed on the bottom hole assembly, and a computer system connected to the linear receiver array.

Limitations in accuracy and computing power requirements impeding conventional Kirchhoff migration and reverse time migration are overcome by using the wave-equation Kirchhoff, WEK, technique with Kirchhoff migration. WEK technique includes forward-propagating a low-frequency wavefield from a shot location among pre-defined source locations, calculating an arrival traveltime of a maximum amplitude of the low-frequency wavefield, and applying Kirchhoff migration using the arrival traveltime and the maximum amplitude.

Methods and seismic shot generation and data collection systems configured to determine a monotonically increased velocity v*(z) from a monotonically increased velocity model by requiring the monotonically increased velocity v*(z) to be nearest to a refraction velocity v(z) determined for an estimated depth z and to be characterized by a positive slope such that the refraction velocity v(z) increases with depth, and to generate a subsurface image based on the estimated depth z and the determined monotonically increased velocity v*(z).

Disclosed are systems and methods for high precision acoustic logging processing for compressional and shear slowness. The method comprises measuring, by a sonic logging tool, sonic data associated with a formation within a borehole, attempting a detection of a first arrival within the sonic data determining whether the attempted detection of the first arrival is accurate, and in response to an accurate detection of the first arrival determining a travel time of the first arrival, generating a coherence map including the first arrival, and determining, based on the coherence map, a characteristic of the formation.