A method is provided for identifying and characterizing structures of interest in a formation traversed by a wellbore, which involves obtaining waveform data associated with received acoustic signals as a function of measured depth in the wellbore. A set of arrival events and corresponding time picks is identified by automatic and/or manual methods that analyze the waveform data. A ray tracing inversion is carried out for each arrival event (and corresponding time pick) over a number of possible raypath types to determine i) two-dimensional reflector positions corresponding to the arrival event for the number of possible raypath types and ii) predicted inclination angles of the reflected wavefield for the number of possible raypath types. The waveform data associated with each time pick (and corresponding arrival event) is processed to determine a three-dimensional slowness-time coherence representations of the waveform data for the number of possible raypath types, which is evaluated to determine azimuth position and orientation of a corresponding reflector, and determine the ray path type of the reflected wavefield. The method outputs a three-dimensional position and/or orientation for at least one reflector, wherein the three-dimensional position of the reflector is based on the two-dimensional position of the reflector determined from the ray tracing inversion and the azimuth position of the reflector determined from the three-dimensional slowness-time coherence representation. 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.

A tangible, non-transitory computer-readable medium configured to store instructions executable by a processor of an electronic device to access a beam migration image of a subsurface target. In addition, the computer-readable medium is configured to store instructions executable by a processor of an electronic device to determine a decomposition criteria based on at least one of subsurface dip inclinations, subsurface dip azimuths, or a combination thereof. Further, the computer-readable medium is configured to store instructions executable by a processor of an electronic device to decompose the beam migration image into a plurality of partial images according to the decomposition criteria to provide various views of the subsurface target. The plurality of partial images are usable by seismic interpreters in exploration for hydrocarbons within the subsurface target.

According to one embodiment, subsurface ray directions in beam migration or subsurface wave propagation directions in reverse time migrations are used to obtain additional Specular Filter (SF) and Dip Oriented Partial Imaging (DOPI) images. SF migration applies a specular imaging condition during migration with a pre-specified subsurface dip field. It boosts the S/N ratio in both images and gathers, by effectively removing migration noise. DOPI images are produced by decomposing a standard migration image according to subsurface dip inclination or/and dip azimuth groups, providing various views of the subsurface image. Both SF and DOPI migration images can supply valuable additional information compared to a standard migration image, and they can be efficiently generated during migration.

A system and method for modeling seismic data using time preserving tomography including storing an initial set of parameter values representing an initial seismic data model. The initial seismic model may correspond to at least two or more ray pairs. Each ray pair may have a traveltime. An altered model may be generated by altering two or more parameter values in the initial set of parameter values for each of two or more ray pairs in the initial model. Altering one parameter value without altering the remaining of the two or more parameter values may correspond to a change in the traveltime of each of the ray pairs, while altering the two or more parameter values in combination typically corresponds to no net change in the traveltime of each of the ray pairs.

A method and apparatus for imaging seismic data includes obtaining an initial model of a subsurface formation, wherein the model includes a plurality of nodes that form at least part of a grid; an initial dip value for the nodes; and a set of origin coordinates for each of the nodes; performing bottom-up ray tracing for each node in the model, resulting in a set of arrival coordinates for each node; identifying a plurality of gathers from the seismic data; for each gather: calculating a set of midpoint coordinates; defining a midpoint vicinity surrounding the set of midpoint coordinates; identifying the nodes having arrival coordinates within the midpoint vicinity; and estimating a unique aperture for each of the gathers based on the respective origin coordinates; storing the estimated apertures in a table; and generating a subsurface volume or image with subsurface reflectors determined with apertures of the respective gathers.

This disclosure describes processes and systems for generating a high-resolution velocity model of a subterranean formation from recorded seismic data gathers obtained in a marine seismic survey of the subterranean formation. A velocity model is computed by iterative FWI using reflections, resolving the velocity field of deep subterranean targets without requiring ultralong offsets. The processes and systems use of an impedance sensitivity kernel to characterize reflections in a modeled wavefield, and then use the reflections to compute a velocity sensitivity kernel that is used to produce low-wavenumber updates to the velocity model. The iterative process is applied in a cascade such that position of reflectors and background velocity are simultaneously updated. Once the low-wavenumber components of the velocity model are updated, the velocity model is used as an input of conventional FWI to introduce missing velocity components (i.e., high-wavenumber) to increase the resolution of the velocity model.

Methods and systems for optimized receiver-based ghost filter generation are described. The optimized ghost filter self-determines its parameters based on an iterative calculation of recorded data transformed from a time-space domain to a Tau-P domain. An initial ghost filter prediction is made based on generating mirror data from the recorded data and using a least squares technique during a premigration stage.

Method for reconstructing subsurface Q depth profiles from common offset gathers (92) of reflection seismic data by performing migration (40), ray tracing (100), CDP-to-surface takeoff angle finding (96, 98), kernel matrix construction (110), depth-to-time conversion and wavelet stretching correction (80), source amplitude spectrum fitting, centroid frequency shift calculation (90), and box-constrained optimization (120).

Example computer-implemented method, computer-readable media, and computer system are described for generating subterranean imaging data based on initial isotropic and/or anisotropic velocity models for the vertical seismic profile (VSP) data and stored ocean bottom sensor (OBS) data. In some aspects, VSP data and OBS data of a subterranean region are received. Angle attributes for each image point are computed to image primary reflection and free surface multiples of the received VSP data and OBS data, respectively. Angle-domain common-image gathers (ADCIG) are generated according to a ray-equation method based on the angle attributes computed based on the received VSP data and OBS data, respectively. The ADCIG are further post-processed.

The present application provides a seismic travel time tomographic inversion method based on two-point ray tracing comprising: collecting seismic data including direct wave travel time and reflected wave travel time; establishing an initial one-dimensional continuously layered model having continuously a varying intraformational velocity; representing a ray parameter p by a variable q, representing a source-receiver distance X by a function X=f(q) of the variable q, solving the function X=f(q) using a Newton iteration method; calculating a theoretical direct wave travel time and reflected wave travel time according to the ray parameter p; comparing the calculated theoretical arrival time with actual arrival time, using an optimal algorithm to adjust velocity parameters of the initial one-dimensional continuously layered model, until a difference between the theoretical direct wave travel time and reflected wave travel time and the actual direct wave travel time and reflected wave travel time complies with a predetermined error standard.