A method for surface estimation of reservoir properties, wherein location
of and average earth resistivities above, below, and horizontally adjacent
to the subsurface geologic formation are first determined using geological
and geophysical data in the vicinity of the subsurface geologic formation.
Then dimensions and probing frequency for an electromagnetic source are
determined to substantially maximize transmitted vertical and horizontal
electric currents at the subsurface geologic formation, using the location
and the average earth resistivities. Next, the electromagnetic source is
activated at or near surface, approximately centered above the subsurface
geologic formation and a plurality of components of electromagnetic
response is measured with a receiver array. Geometrical and electrical
parameter constraints are determined, using the geological and geophysical
data. Finally, the electromagnetic response is processed using the
geometrical and electrical parameter constraints to produce inverted
vertical and horizontal resistivity depth images. Optionally, the inverted
resistivity depth images may be combined with the geological and
geophysical data to estimate the reservoir fluid and shaliness properties.