DETECTION OF RESISTIVITY OF OFFSHORE SEISMIC STRUCTURES MAINLY USING VERTICAL MAGNETIC COMPONENT OF EARTH'S NATURALLY VARYING ELECTROMAGNETIC FIELD.

摘要

The invention measures the vertical component Hz of a magnetic field arising from natural sources (MT) simultaneously at a plurality of points on the sea floor to determine places having a non-zero vertical component Hz indicative of an edge of a resistive body (structure), in order to determine whether or not a sub-bottom geologic structure, known from marine seismic measurements, exhibits a resistivity contrast with the surrounding rocks, a positive contrast being interpreted as indicating hydrocarbon charge within the structure.