Methods, systems, and computer program products for characterizing materials in a wellbore having multiple casing strings uses well completion data and instantaneous frequency, instantaneous phase, and/or amplitude attributes, including waveform amplitude and instantaneous amplitude, of an acoustic waveform to determine material densities, acoustic velocities and acoustic travel distances for the materials between the various stages of casings.

Methods and devices according to various embodiments perform full-wave inversion jointly for datasets acquired at different times over the same underground formation using a time-lag cost function with target regularization terms. This approach improves the 4D signal within reservoirs and suppresses 4D noise outside.

A technique for reconstructing a seismic wavefield includes receiving data over one or more channels of a plurality of channels from a plurality of stations. The data is recorded by a plurality of seismic receivers and represent measurements of properties of the seismic wavefield. Each station includes a region in space including one or more seismic receivers. Each channel either measures a property of the seismic wavefield or a property of the seismic wavefield after the seismic wavefield has undergone a known transformation. At least one channel is derived as a function of one or more other channels. The technique includes using a processor based machine to process the data to model the seismic wavefield as a sum of basis functions; apply to the basis functions at least one forward transformation that describes the measurements received over the channel(s); and determine optimum basis functions based at least in part on the measurements.

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.

An object of the present invention is to provide a system and a method for evaluating an urban ground stability using traffic noise, which derive a physical property (S wave velocity) according to a depth by performing an inversion for a surface wave dispersion curve generated by traffic vibration in order to more accurately derive an underground physical property value (S wave velocity).

In order to achieve the object, a system for evaluating an urban ground stability using traffic noise according to the present invention includes: a signal measurement unit measuring a passive elastic wave signal generated by the traffic noise, and acquiring an elastic wave signal containing refracted waves using an artificial transmission source in an exploration area; and a server performing an inversion by applying a surface wave dispersion curve inversion technique to a frequency-phase velocity dispersion curve according to the passive elastic wave signal or the elastic wave signal containing the refracted wave.

Marine survey data resulting from a first signal comprising a signal representing a flat spectral far-field pressure generated by a marine vibrator source swept over a frequency range according to a time function of motion such that acceleration of the marine vibrator source is a flat function in a frequency domain can be used to improve full waveform inversion. For example, full waveform inversion can be performed using the marine survey data received from the first signal and from a second signal generated by an impulsive seismic source to estimate a physical property of a subsurface location.

Systems and methods that include receiving reservoir data of a hydrocarbon reservoir, receive an indication related to selection of a wavefield propagator, application of the wavefield propagator utilizing Fourier Finite Transforms and Finite Differences to model a wavefield associated with a Tilted Orthorhombic media representative of a region of a subsurface comprising the hydrocarbon reservoir, and processing the reservoir data in conjunction the wavefield propagator to generate an output for use with seismic exploration above a region of a subsurface comprising the hydrocarbon reservoir and containing structural or stratigraphic features conducive to a presence, migration, or accumulation of hydrocarbons.

Methods and systems are disclosed. The method includes determining a seismic acquisition grid for a seismic survey, composed of a first receiver grid, a second receiver grid, and a source grid, deploying a first plurality of seismic receivers according to the locations of the first receiver grid, and a second plurality of seismic receivers according to locations of the second receiver grid, and activating a seismic source at location based on the source grid. The method further includes recording a first seismic dataset using the first plurality of receivers and a second seismic dataset using the second plurality of receivers, and generating a velocity model using a velocity analysis method based on the first seismic dataset. The method still further includes forming a seismic image based on the velocity model and the second seismic dataset; and determining a location of a hydrocarbon reservoir based on the seismic image.

A system may obtain orthogonal pairs of acoustic waveforms obtained by a rotating downhole acoustic tool. The downhole tool may include an acoustic transmitter and an acoustic receiver. A computing device communicatively coupled to the downhole tool that instructs the transmitter to generate the various waveforms detected by the acoustic receiver and store the various waveforms in a buffer. Each waveform of a subset of the various waveforms oriented in a similar direction may be stacked to generate a composite waveform with reduced noise. The computing system may determine an orthogonal pair of waveforms based on the composite waveform and remaining waveforms.

Aspects of the disclosure provide for a method using clusters of sonic peaks from a logging tool to generate a log of an acoustic property of the formation as a function of depth.