The analysis of rock anisotropy in terms of seismic velocities and within the context of rock physics (Biot-Gassmann theory of poroelasticity) provides important information for the evaluation of the stress state (tensors) of rocks, detection of the directions of formation weaknesses, helps in the estimation of overall permeability and failure prediction. Understanding the influence of stress and pore pressure on seismic velocities is important for 4-D reflection seismic interpretation, AVO analysis and reservoir modeling. Laboratory measurements were carried out on spherical shale samples from the overburden under confining stress up to 400 MPa, by means of ultrasonic soundings in 132 independent directions. Such an approach enables the estimation of 3-D elastic anisotropy. Since the sandstones were partly unconsolidated, it was not possible to take ultrasonic measurements. To overcome this, we developed a method for stress induced azimuthal anisotropy estimation using only cross-dipole logging data. These results give the possibility for anisotropic correction in AVO analysis.


Article metrics loading...

Loading full text...

Full text loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error