There is provided herein a system and method of seismic data collection for land and marine data that utilizes narrowband to monochromatic low-frequency non-impulsive sources designed to optimize the ability of migration/inversion algorithms to image the subsurface of the Earth, in particular, full-waveform inversion.

Wavefield separation methods and systems that adjust near-continuous pressure and particle motion wavefields based on distance moved along a vessel track by the sensors when the wavefields were measured are disclosed. Methods and systems correct for the motion of the receivers in towed streamer seismic data in order to obtain a wavefield with approximately stationary-receiver locations. Wavefield separation may then be applied to the wavefield with approximately stationary-receiver locations.

Disclosed herein are embodiments of systems, methods, and computer program products for determining fracture and stress characterization using layer thickness variation over an azimuthally anisotropic medium, which may include one or more of the following functions: acquiring seismic data by recording reflected seismic waves in at least two directions; sorting of the seismic data so that offset is zero at a center and increases radially from a single common-point (CMP) gather for a plurality of data points; generating a multi-dimensional volume by juxtaposing a set of common-offset sections by one of their common-depth point (CDP) and CMP locations; selecting reflectors for each layer in the one of the multi-dimensional volume; computing layer parameters including effective anisotropy and interval anisotropy for each layer in the multi-dimensional volume based on a geometry of the reflectors selected for each layer in the multi-dimensional volume; and applying the layer parameters to an earth model.

A method and system for modeling a subsurface structure at a time when the structure was originally formed. A first model having non-planar horizons representing a current subsurface structure may be used to calculate a vector field based on the non-planar geometry of the horizons of the model. The vector field may be non-uniform or uniform. Geographic coordinates of the first model may be transformed to paleo-geographic coordinates of a model representing the subsurface structure in the past, where the non-planar horizons in the first model are transformed to planar horizons in the second model. A set of points describing one or more fractures in the subsurface structure may be used to calculate a tuning parameter to correct a first set of paleo-geographic coordinates. A second set of coordinates representing an improved prediction at a time period when the subsurface structure was originally formed may be generated.

A method, including: obtaining a velocity model generated by an acoustic full wavefield inversion process; generating, with a computer, a variable Q model by applying pseudo-Q migration on processed seismic data of a subsurface region, wherein the velocity model is used as a guided constraint in the pseudo-Q migration; and generating, with a computer, a final subsurface velocity model that recovers amplitude attenuation caused by gas anomalies in the subsurface region by performing a visco-acoustic full wavefield inversion process, wherein the variable Q model is fixed in the visco-acoustic full wavefield inversion process.

A least-square migration, LSM, based method for generating a 4D image of a subsurface, the method including receiving seismic data d related to the subsurface, the seismic data d including a baseline dataset d.sub.B and a monitor dataset d.sub.M, calculating a baseline filter .sub.B and a monitor filter .sub.M based on a same common reflectivity r of the subsurface and corresponding remigrated baseline data m.sub.B1 and remigrated monitor data m.sub.M1 so that the base filter .sub.B applied to the remigrated baseline data m.sub.B1 equals the monitor filter .sub.M applied to the remigrated monitor data m.sub.M1, applying the baseline filter .sub.B to raw migrated baseline data m.sub.B0 and applying the monitor filter .sub.M to raw migrated monitor data m.sub.M0 to generate LSM baseline data m.sub.B and LSM monitor data m.sub.M, and generating the 4D image of the subsurface based on the LSM baseline data m.sub.B and the LSM monitor data m.sub.M.

A method is described for monitoring a stimulated reservoir volume (SRV) including receiving simulation parameters, performing 3D fully coupled quasi-static poro-elastic finite difference modeling using the simulation parameters, wherein the 3D fully coupled quasi-static poro-elastic finite difference modeling is based on a rescaling of solid rock and fluid flow density parameters and generates simulated temporal quasi-static stresses, and pore pressure. In addition, simulated stresses may be used for performing calculation of the 3D rotation of the simulated stresses to principal directions; performing calculation of the temporal 3D Mohr-Coulomb (MC) failure criteria from the calculated principal stresses and the simulated pore pressure for all or selected time steps; and displaying the computed temporal MC failure criteria results on a graphical display. The method may also be used in time-lapse monitoring of the reservoir for microseismic depletion delineation.

The embodiment of the disclosure relates to an elastic wave stress tensor double-dot product seismic imaging method and device. The method comprises: obtaining a decoupled particle vibration velocity vector wave field by utilizing the existing decoupled wave equation method for the detected wave field; then obtaining a decoupled pseudo-stress wave field by constructing the decoupled pseudo-stress equation by using the obtained decoupled particle vibration velocity vector wave field; and finally computing a source second-order stress tensor wave field and the decoupled detected second-order stress tensor wave field by using the double-dot product cross-correlation imaging condition algorithm, to obtain the final scalar imaging results. With the embodiment of the present disclosure, the combined P-wave and S-wave stress exploration can be realized, therefore, the obtained imaging results can be used to accurately predict the risk of gas exploration.

Aspects described herein provide for methods and apparatus for characterizing azimuthal heterogeneities in a barrier installed outside an outer casing in a borehole traversing a formation in a cased hole configuration including an inner and outer casing. The approach is based on specific attributes in sonic signals acquired with an azimuthal and axial array receiver system located inside the inner casing. The methods include slowness-time-coherence (STC) processing based on specific arrivals identified in data acquired by axial arrays associated with multiple azimuthal sections of the receiver system. The specific arrivals contain STC signatures that can be examined in terms of coherence amplitude and localization within STC maps. Based on specific attributes in the sonic signals, an azimuthal coverage of the outer casing annular contents can be created.

In some aspects, reservoir characterizations of subterranean regions can be enhanced by using realtime fracture matching techniques for capturing the time dependent evolution of fracture parameters based on the occurrence of the time microseismic events generated by stimulation treatments. These microseismic events may further be used to determine hydraulic fracture planes, identify areas of concentration of high density microseismic events, identify and analyze complex fracture networks, and use these and other techniques to enhance the reservoir characterization.