METHOD FOR DETERMINING EARTH VERTICAL ELECTRICAL ANISOTROPY IN MARINE ELECTROMAGNETIC SURVEYS

摘要

The marine method for determining the earth vertical electrical anisotropy uses offshore electromagnetic survey measurements (1). The method requires both online and offline data and includes at least one electromagnetic field component sensitive at least predominantly to vertical resistivity and another component sensitive at least predominantly to horizontal resistivity (4). Using the horizontal electric dipole source the online Ez and offline Hz measurements are preferred. For the horizontal magnetic dipole source the online Hz and offline Ez are preferred. The magneto telluric data may be substituted for controlled source data sensitive to horizontal resistivity. Maxwell's equation is solved by forward modeling or by inversion using the resistivity models of the subsurface that are either isotropic or anisotropic.