Remote reservoir resistivity mapping

A method for surface estimation of an inverted resistivity depth image of a subsurface geologic formation, comprising the steps of:

• determining the location of and average earth resistivity above, below, and horizontally adjacent to the subsurface geologic formation using geological and geophysical data from the vicinity of the subsurface geologic formation;
• determining dimensions and probing frequency for an electromagnetic source to substantially maximize transmitted vertical and horizontal electric currents at the subsurface geologic formation using the location and the at least one average earth resistivity, said source comprising six or more grounded linear radial electrodes of equal lengths placed along radii separated by equal angles whose radial projections intersect at a common central point, continuously grounded linear terminating electrodes connected substantially orthogonally at each end of the grounded radial electrodes;
• activating the electromagnetic source at or near the surface of the earth, approximately centered above the subsurface geologic formation;
• measuring a plurality of components of electromagnetic response with a receiver array;
• determining one or more geometrical and electrical parameter constraints, using the geological and geophysical data;
• and
• processing the electromagnetic response using the geometrical and electrical parameter constraints to produce the inverted resistivity depth image.

A method for surface estimation of one or more properties of a subsurface geologic formation, comprising the steps of:

• determining the location of and at least one average earth resistivity for the vicinity of the subsurface geologic formation using geological and geophysical data from the vicinity of the subsurface geologic formation;
• determining dimensions and probing frequency for an electromagnetic source to substantially maximize transmitted vertical and horizontal electric currents at the subsurface geologic formation using the location and the at least one average earth resistivity, said source comprising six or more grounded linear radial electrodes of equal lengths placed along radii separated by equal angles whose radial projections intersect at a common central point;
• activating the electromagnetic source at or near the surface of the earth, approximately centered above the subsurface geologic formation;
• measuring a plurality of components of electromagnetic response with a receiver array;
• determining one or more geometrical and electrical parameter constraints, using the geological and geophysical data;
• processing the electromagnetic response using the geometrical and electrical parameter constraints to produce one or more inverted resistivity depth images of the subsurface geologic formation;
• and
• combining the inverted resistivity depth images with the geological and geophysical data to estimate the properties.

A method for surface estimation of one or more properties of a subsurface geologic formation, comprising the steps of:

• determining the location of and at least one average earth resistivity for the vicinity of the subsurface geologic formation;
• determining dimensions and probing frequency for an electromagnetic source to substantially maximize transmitted vertical electric currents at the subsurface geologic formation using the location and the at least one average earth resistivity;
• activating the electromagnetic source at or near the surface of the earth, approximately centered above the subsurface geologic formation;
• measuring at least a vertical electromagnetic response with a receiver array;
• determining one or more geometrical and electrical parameter constraints, using geological and geophysical data from the vicinity of the subsurface geologic formation;
• processing the electromagnetic response using the geometrical and electrical parameter constraints to estimate the one or more properties.