A method for identifying a leak for dynamic logging may comprise estimating a Stoneley wave slowness, separating a Stoneley wave into an up-going Stoneley wave and a down-going Stoneley wave, estimating an amplitude of the up-going Stoneley wave and the down-going Stoneley wave, identifying a difference between the amplitude of the up-going Stoneley wave and the down-going Stoneley wave, forming an amplitude summation curve or an amplitude difference curve, and identifying a location of the leak.

An acoustic logging method that may comprise acquiring waveforms for multiple acoustic wave modes as a function of tool position in a borehole; deriving position-dependent mode dispersion curves from the waveforms; accessing a computed library of dispersion curves for a vertical shear slowness (s) and a Thomsen gamma () of a given acoustic wave mode as a function of frequency; interpolating dispersion curves in the computed library to an assumed known compressional wave slowness, a borehole radius, a formation density, a mud density, and a mud slowness; computing an adaptive weight; and inverting dispersion curve modes jointly for a shear wave anisotropy, a vertical shear wave slowness, an inverted mud slowness, and an inverted mud density as a function of depth. An acoustic logging system may comprise a logging tool, a conveyance attached to the logging tool, at least one sensor, and at least one processor.

A method for enhanced dispersion analysis begins with obtaining a plurality of measured waveforms, for example from two or more receivers of an acoustic logging tool placed in a borehole. The measured waveforms are divided into common gathers, and waveforms of each common gather are enhanced. The enhancement begins by calculating a travel time curve for a selected target mode of the common gather waveforms. Using the travel time curve, waveforms of the selected target mode are aligned to have zero apparent slowness. The aligned waveforms are filtered to suppress non-target mode waves. The aligned waveforms are then enhanced, and used to generate an enhanced dispersion curve of the selected target mode.

Computing device, computer instructions and method process input seismic data d recorded in a first domain by seismic receivers that travel in water, the input seismic data d including pressure and particle motion measurements, including up-going and down-going wave-fields. A model p is generated in a second domain by solving an inverse problem for the input seismic data d, wherein applying an L transform to the model p describes the input data d. An L transform, which is different from the L transform, is then applied to the model p to obtain an output seismic data in the first domain, the output seismic data having a characteristic imparted by the transform L. The characteristic is related to pressure wave-fields and/or particle motion wave-fields interpolated at positions in-between the input seismic receivers. An image of the surveyed subsurface is generated based on the output seismic dataset.

Effects of time variability of water velocities in seismic surveys are addressed. Traveltime discontinuities in the input seismic data which are associated with the time-variable water velocities are determined. The input seismic data is transformed from a data space that contains the traveltime discontinuities into a model space which does not contain the traveltime discontinuities. Then the transformed seismic data is reverse transformed from the model space back into the data space.

A method of generating geophysical data using at least one source. The method may include the steps of generating a geophysical wavefield with a varying signature using at least one source, wherein the signature is varied in a periodic pattern.

An acoustic logging method that may comprise acquiring waveforms for multiple acoustic wave modes as a function of tool position in a borehole; deriving position-dependent mode dispersion curves from the waveforms; accessing a computed library of dispersion curves for a vertical shear slowness (s) and a Thomsen gamma () of a given acoustic wave mode as a function of frequency; interpolating dispersion curves in the computed library to an assumed known compressional wave slowness, a borehole radius, a formation density, a mud density, and a mud slowness; computing an adaptive weight; and inverting dispersion curve modes jointly for a shear wave anisotropy, a vertical shear wave slowness, an inverted mud slowness, and an inverted mud density as a function of depth. An acoustic logging system may comprise a logging tool, a conveyance attached to the logging tool, at least one sensor, and at least one processor.

Systems and methods for picking seismic stacking velocity based on structures in a subterranean formation include: receiving seismic data representing a subterranean formation; generating semblance spectrums from the seismic data representing the subterranean formation; smoothing the semblance spectrums; and picking stacking velocities based on the smoothed semblance spectrums.

Systems and methods of performing a seismic survey are described. The system can receive seismic data in a first domain, and transform the seismic data into a tau-p domain. The system can identify a value on an envelope in the tau-p domain, select several values on the tau-p envelope using a threshold, and then generate a masking function. The system can combine the masking function with the tau-p transformed seismic data, and then perform an inverse tau-p transform on the combined seismic data. The system can adjust amplitudes in the inverse tau-p transformed combined seismic data, and identify one or more coherent events corresponding to subsea lithologic formations or hydrocarbon deposits.

A method of invertibly transforming acoustic log signals comprises steps of: a) inserting into a borehole (11), forming part of a borehole-formation system (11, 12) in which the borehole (11) penetrates a rock formation (12), an elongate acoustic logging tool (17), the acoustic logging tool including at least one dipole acoustic source (28) and, spaced from the acoustic source along the logging tool, a sequential array of two or more acoustic signal receiver stations (29, 31, 32, 33, 34, 36, 37, 38), the receiver stations each including at least one receiver and being spaced along the logging tool (17) from the acoustic source by successively greater known transmitter-receiver distances; b) causing the acoustic source (28) to emit acoustic energy in a manner (I) effecting the propagation in the borehole-formation system (11, 12) towards the receiver stations (29, 31, 32, 33, 34, 36, 37, 38) of plural signal packets exhibiting paths characteristic of at least first and second respective modes one or more of which is dispersive and (II) stimulating at least one receiver of each sequential receiver station (29, 31, 32, 33, 34, 36, 37, 38) to generate at least one output signal per receiver station that is indicative of the signal packets, received at the at least one receiver of each respective receiver station (29, 31, 32, 33, 34, 36, 37, 38), representing the modes in combination with one another; c) transforming the output signals into respective transformed mode signals containing phase and amplitude information of each respective mode across the array and in which estimated phase and amplitude information are linked by an operator to the slowness and attenuation characteristics of the respective mode and the transmitter-receiver distance of the respective receiver station; and d) using the estimated phase and amplitude information for each mode to extract slowness and attenuation information for each mode from the output signals.