Modeling an elastic stiffness tensor in a transverse isotropic subsurface medium

A computer-readable non-transitory medium containing computer-executable code that when read by a computer causes the computer to perform a method for modeling an elastic stiffness tensor in a transverse isotropic subsurface medium, the method comprising:

• acquiring well log data indicative of physical properties of the subsurface medium along a direction parallel to a symmetry axis along at least one well, the direction parallel to the symmetry axis passing through the transverse isotropic subsurface medium;
• dividing the transverse isotropic subsurface medium into an effective anisotropic layer and an isotropic layer such that a sum of an effective anisotropic layer volume fraction and an isotropic layer volume fraction equals one;
• modeling effective anisotropic layer elastic parameters while taking into consideration a source of anisotropy;
• modeling isotropic layer elastic parameters using the anisotropic layer elastic parameters and the acquired well log data;
• using the modeled effective anisotropic layer elastic parameters and the modeled isotropic layer elastic parameters to upscale the effective anisotropic layer and the isotropic layer into the transverse isotropic subsurface medium comprising a single layer and to determine the elastic stiffness tensor for the transverse isotropic subsurface medium;
• calculating transverse isotropic subsurface medium p-wave velocities and transverse isotropic subsurface medium s-wave velocities based on the elastic stiffness tensor;
• and
• generating an image of the transverse isotropic subsurface medium based on the transverse isotropic subsurface medium p-wave velocities and transverse isotropic subsurface medium s-wave velocities,
• wherein the well log data is acquired inside a well and is indicative of physical properties of the subsurface medium p-wave and s-wave velocities characterize anisotropy effects in reservoir geophysics.

A computing system for modeling an elastic stiffness tensor in a transverse isotropic subsurface medium, the computing system comprising:

• a storage device comprising well log data indicative of physical properties of the subsurface medium along a direction parallel to a symmetry axis along at least one well, the direction parallel to the symmetry axis passing through the transverse isotropic subsurface medium;
• and
• a processor in communication with the storage device and configured to:
• divide the transverse isotropic subsurface medium into an effective anisotropic layer and an isotropic layer such that a sum of an effective anisotropic layer volume fraction and an isotropic layer volume fraction equals one;
• model effective anisotropic layer elastic parameters while taking into consideration a source of anisotropy;
• model isotropic layer elastic parameters using the effective anisotropic layer elastic parameters and the acquired well log data;
• use the modeled effective anisotropic layer elastic parameters and the modeled isotropic layer elastic parameters to upscale the effective anisotropic layer and the isotropic layer into the transverse isotropic subsurface medium comprising a single layer and to determine independent members of the elastic stiffness tensor for the transverse isotropic subsurface medium;
• calculate transverse isotropic subsurface medium p-wave velocities and transverse isotropic subsurface medium s-wave velocities based on the elastic stiffness tensor;
• and
• generate an image of the transverse isotropic medium based on the transverse isotropic medium based on the transverse isotropic subsurface medium p-wave velocities and the transverse isotropic subsurface medium s-wave velocities,
• wherein the elastic stiffness tensor and the transverse isotropic subsurface medium p-wave and s-wave velocities characterize anisotropy effects in reservoir peophysics.