Methods for inversion of seismic data to infer subsurface physical property parameters, comprising constructing an inhomogeneous anisotropy model and/or inhomogeneous V.sub.S/V.sub.P or V.sub.P/V.sub.S model; and inverting the seismic data in a sequential or simultaneous approach to obtain at least one subsurface physical property parameter using an elastic inversion algorithm and the inhomogeneous anisotropy model and/or inhomogeneous V.sub.S/V.sub.P or V.sub.P/V.sub.S model. Constructing an inhomogeneous anisotropy model may comprise deriving geobodies from at least one of seismic facies analysis, regional geologic information, or seismically derived earth models; and adjusting at least one of , , , or parameters of the elastic stiffness tensor matrix in a homogeneous anisotropy model in areas corresponding to the geobodies. Constructing an inhomogeneous V.sub.S/V.sub.P or V.sub.P/V.sub.S model may comprise deriving geobodies and adjusting values in a homogeneous V.sub.S/V.sub.P or V.sub.P/V.sub.S model in areas corresponding to the geobodies.

A method, including: obtaining Earth models including velocity, anisotropy, and attenuation reconstructing a source wavefield using the Earth models; reconstructing a receiver wavefield using the Earth models, wherein the reconstructing the source wavefield and the receiver wavefield each include applying an attenuation operator that increases an amplitude of down-going wavefields within an attenuation body and that decreases an amplitude of up-going wavefields within the attenuation body; applying an imaging condition to the source wavefield and receiver wavefield for a plurality of shots; and generating a subsurface image by stacking images for the plurality of shots.

Systems and methods for determining mechanical properties of anisotropic media are disclosed. A method for determining mechanical properties of an anisotropic media includes obtaining log data of the anisotropic media, the log data corresponding to measurements of the anisotropic media collected with a logging tool; determining values for a plurality of first stiffness components of a stiffness matrix based on horizontal and vertical velocities derived from the log data; determining an upper bound for a second stiffness component of the stiffness matrix based on the values for the plurality of first stiffness components; estimating a value for the second stiffness component based on the determined upper bound; determining a mechanical property of the anisotropic media based on the estimated value of the second stiffness component; and providing the determined mechanical property.

A method for determining properties of a laminated formation traversed by a well or wellbore employs measured sonic data, resistivity data, and density data for an interval-of-interest within the well or wellbore. A formation model that describe properties of the laminated formation at the interval-of-interest is derived from the measured sonic data, resistivity data, and density data for the interval-of-interest. The formation model represents the laminated formation at the interval-of-interest as first and second zones of different first and second rock types. The formation model is used to derive simulated sonic data, resistivity data, and density data for the interval-of-interest. The measured sonic data, resistivity data, and density data for the interval-of-interest and the simulated sonic data, resistivity data, and density data for the interval-of-interest are used to refine the formation model and determine properties of the formation at the interval-of-interest. The properties of the formation may be a radial profile for porosity, a radial profile for water saturation, a radial profile for gas saturation, radial profile of oil saturation, and radial profiles for pore shapes for the first and second zones (or rock types).

High fidelity velocity models are generated for acoustic vertically transverse isotropic media by taking advantage of full-waveform based modeling using VSP data. The present disclosure determines VTI parameters in acoustic media using pseudo-acoustic equations which can eliminate the contribution from shear waves, and thus significantly reduce the time needed to perform inversion. The methods disclosed herein provide workflows for performing full waveform inversion to provide velocity models used to generate seismic images with high quality and resolution.

A downhole tool having a transmitter array with azimuthally spaced transmitters and receiver arrays with azimuthally spaced receivers. Methods of operation include transmitting an acoustic signal from an individual one of the transmitters, sensing an attribute of the acoustic signal with the receivers, and evaluating a characteristic of a portion of a downhole feature based on response signals generated by the first and second receivers. Each response signal is indicative of the acoustic signal attribute sensed by the corresponding receivers. This is repeated with different individual ones of the transmitters and receivers until the evaluated portions of the downhole feature collectively extend around a wellbore.

A method, apparatus, and program product estimate anisotropic properties of an anisotropic formation based at least in part on determinations of a deviation of a wellbore associated with the anisotropic formation and an availability of non-sonic measurement data associated with the anisotropic formation. The determinations are used in the selection of at least one computer-implemented model that in turn may be applied to determine one or more unknown elastic constants for an elastic stiffness matrix.

Systems and methods for estimating orthorhombic anisotropy parameters of subsurface rock layers are provided. An initial three-dimensional (3D) model of layers in a subsurface formation is generated. Particular combinations of seismic source and receiver locations associated with a vertical seismic profile (VSP) survey of the formation are selected based on a simulation of seismic wave propagation through each layer of the initial 3D model. A global inversion is performed using data points selected from travel time data associated with the VSP survey in order to estimate different sets of anisotropy parameters for the layers of the initial 3D model, where the selected data points correspond to the selected source-receiver combinations. The initial 3D model is refined with an optimal set of anisotropy parameters selected from the estimated parameter sets. The refined 3D model is provided for seismic analysis and well planning operations to be performed for the subsurface formation.

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.

Modeling an elastic stiffness tensor in a transverse isotropic subsurface medium acquires well log data for at least one well passing through the transverse isotropic subsurface medium. The transverse isotropic subsurface medium is divided into an effective anisotropic layer and an isotropic layer. The effective anisotropic layer elastic parameters are modeled, and the isotropic layer elastic parameters are modeled using the effective anisotropic layer elastic parameters and the acquired well log data. The modeled effective anisotropic layer elastic parameters and the modeled isotropic layer elastic parameters are used to upscale the effective anisotropic layer and the isotropic layer into the transverse isotropic subsurface medium comprising a single layer and to determine the five members of the elastic stiffness tensor for the transverse isotropic subsurface medium.