Some Constrains for Velocity Prediction by Means of the Porosity Deformation Approach.
S.I. Mayr, V.A. Sviridov and S.A. Shapiro
Event name: 79th EAGE Conference and Exhibition 2017
Session: Rock Physics I - Pore structures and Stress effects
Publication date: 12 June 2017
Info: Extended abstract, PDF ( 1.25Mb )
Price: € 20
For better prediction of velocities in rocks under anisotropic loading conditions we use the porosity deformation approach, which describes the compliances. Previous investigations suggest that an isotropic stress sensitivity tensor, i.e. only one value to describe the stress dependency can be used. Using the Porosity deformation approach we analyze VTI rocks under uniaxial loading conditions assuming an seismically elliptical rock and an isotropic stress sensitivity tensor. We show that the non diagonal elements of the compliances are constant, if only the change of compliant porosity is considered, whereas for change of stiff porosity an linear change is predicted. We make use of data obtained in a room dry high porous bunter sandstone to prove that measurement errors of the oblique velocity vpq have a high influence on S12 and S13. We here use the assumption of zero anellipticity to estimate the quasi p-wave velocity. For this high porous rock the influence of the stiff porosity is to be considered particularly for higher stresses.