Imagerie multi-fréquentielle d'un réservoir géothermal au Lamentin (Martinique, France) par méthode de Longue Electrode Mise-à-la-Masse

Abstract

National audienceWithin the frame of geothermal exploration, a CSEM survey was performed at the Le Lamentin area (Martinique, French Indies) using 400m long energized metallic casings of two deep exploration boreholes as long electrodes for current injection (the so-called double Longue Electrode Mise-à-la-Masse setup, hereafter 2xLEMAM). Apparent resistivity maps were derived from the in-phase electric fields. Frequency dependent apparent resistivity maps and profiles reveal a very conductive area north of the Fort de France Bay connected to a known poly-phased geothermal system and shallow salt water intrusion. The most conductive body is proposed to be the geo-electrical signature of an active hydrothermal system, superimposed on the signature of a conductive fossilized geothermal system. It is spatially well correlated with high temperature borehole logs