ELECTRICAL TECHNIQUE

A VERY CONSISTANT GEOPHYSICAL MODEL OF ELECTRICAL ANOMALIES OVER OIL AND GAS FIELDS HAS EMERGED FROM OVER SEVEN YEARS (1500 LINE-KILOMETERS OF COVERAGE IN OVER 30 DIFFERENT BASINS IN THE U.S. AND CANADA) OF RESEARCH. THE TYPICAL ELECTRICAL RESPONSE OBSERVED OVER A HYDROCARBON ACCUMULATION IS A LOW-RESISTIVITY VERTICAL COLUMN OR PLUME WHICH EXTENDS FROM THE TRAP TO, OR VERY CLOSE TO, THE SURFACE. THE RESISTIVITY WITHIN THIS PLUME IS TYPICALLY 20% TO 40% BELOW THE AVERAGE BACKGROUND RESPONSE. EARLIER INVESTIGATIONS OF ELECTRICAL PHENOMENON OVER OIL AND GAS FIELDS WERE MADE PREDOMINATELY WITH DIPOLE-DIPOLE IP TECHNIQUE. THIS TECHNIQUE HAS A) VERY POOR LATERAL RESOLUTION AND B) IS VERY SUSCEPTIBLE TO CONTAMINATION FROM MAN-MADE ELECTRICALLY GROUNDED STRUCTURES. THESE TWO FEATURES LEAD MOST RESEARCHERS TO THE CONCLUSION THAT ELECTRICAL TECHNIQUES WERE NOT VIABLE EXPLORATION TOOLS. CSAMT, A HIGH-RESOLUTION RESISTIVITY SOUNDING TECHNIQUE, NOW APPEARS TO HAVE THE SENSITIVITY AND LATERAL RESOLUTION TO ADEQUATELY DELINEATE SUBSURFACE GEOCHEMICAL ALTERATION ABOVE OIL AND GAS FIELDS. CSAMT IS A FAR-FIELD TECHNIQUE WHICH IS CONSIDERABLY LESS SUSCEPTIBLE TO CONTAMINATION FROM GROUNDED STRUCTURE. CSAMT APPEARS TO BE A VIABLE EXPLORATION TOOL WHICH CAN BE UTILIZED FOR BOTH STRATIGRAPHIC AND STRUCTURAL TRAPS.