Disclosed is a method of characterising a subsurface volume. The method comprises: extracting a geobody from seismic data arranged within a discretised volume comprising a plurality of cells, the geobody comprising a subset of the plurality of cells, each cell of the subset having one or more properties indicative of a particular fluid phase. The extraction of the geobody comprises: determining a propagation probability value for each cell indicative of the probability that a front will propagate through the cell; beginning from a source within the discretised volume, using the propagation probability value to calculate a travel-time for each cell, the travel time describing the time the front takes to travel from the source point to the cell; and using the traveltimes to extract the geobody from the seismic data.

Computing systems, computer-readable media, and methods for seismic processing. The method includes receiving seismic data including acquired seismic waveforms that were acquired from a seismic receiver and represent a subterranean area, generating synthetic waveforms based on an initial model of the subterranean area, determining a model error by minimizing a local travel time shift error between one or more of the acquired seismic waveforms and one or more of the synthetic waveforms, and adjusting the initial model based on the model error to generate an adjusted model.

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.

A method and system for processing a slowness profile. A method may comprise disposing a geophone array into a borehole, positioning the geophone array at a first location within the borehole; discharging a seismic source; positioning the geophone array at a second location within the borehole; discharging the seismic source, wherein the seismic source produces an acoustic wave; recording a vertical seismic profiling dataset, wherein vertical seismic profiling comprises a dataset of recorded acoustic waves by the geophone array at the first location within the borehole and the second location within the borehole; picking a first gap travel time from the vertical seismic profiling dataset; and determining the slowness profile, wherein the slowness profile comprises determining a slowness of the acoustic wave through a formation by the geophone arrays. A well system may comprise a geophone array, comprising a plurality of geophones, and an information handling system.

PP and PS seismic data are jointly inverted in a stratigraphic grid, using different time axes for PP and PS reflections. A ratio of PP and of PS waves'travel times inside a same layer cell maintained to be a function of a ratio of a P-wave propagation velocity and of an S-wave propagation velocity therein. Since PP and PS seismic amplitudes and travel times are due to elastic properties of the same structure, they can be inverted at the same time to provide better estimates of these elastic properties.

A method including obtaining, by a computer processor, a sonic waveform for each of a plurality of source and receiver positions along a borehole, and a sonic wave propagation velocity of a target event for the plurality of positions. Further, performing, a linear moveout correction on the sonic waveforms based on the velocity and stacking the linear moveout corrected waveforms to generate a stacked waveform at the plurality of positions. The method further includes determining an arrival-time of the target event on the stacked waveforms based on an extremum of a first objective and predicting a candidate arrival-time of the target event for the sonic waveform at the plurality positions based on the arrival-time of the target event on the stacked waveforms, and the sonic velocity. The method still further includes determining an arrival-time for the target event on the sonic waveform at the plurality positions within the borehole based on the candidate arrival-time of the target event and an extremum of a second objective function.

Logging of data by a downhole tool disposed in a borehole may be affected by tool wave effects. The tool waves appear in the first echo of casing wave arrivals and the amplitudes may be much larger than casing wave arrivals. The estimates of casing wave amplitude are biased due to these tool wave arrivals when using conventional cement-bond logging (CBL) processing. An automated adaptive inversion-based array processing for CBL evaluation using a downhole tool provides an improvement in the calculation of a bonding index.

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.

A new method for iteratively picking the seismic first breaks and conducting imaging of the near-surface velocity structures in an iterative fashion is provided that the first-break picks of the input seismic data are applied to image the near-surface velocity structures and the calculated travel times associated with the updated velocity structures are applied to help refine the first-break picks in the first break picking process until first-break picks satisfy a number of quality control criteria, statics solutions are optimized, and the near surface imaging reaches an acceptable data misfit. This invention produces a velocity model that can be used for near surface statics corrections or for the prestack depth migration.

A method of determining an arrival-time of a first seismic event in a seismic data set including, obtaining the seismic data set and an initial seismic velocity model, and determining an updated seismic velocity model based on the seismic data set. Furthermore, the method includes determining a simulated arrival-time of the first seismic event based on the updated seismic velocity model and defining a predicted time-window based on the simulated arrival-time of the first seismic event, and picking the arrival-time of the first seismic event in the seismic data set based on the predicted time-window.