CALCULATION OF LOW-RANGE FLOW VELOCITIES IN FRACTURED CARBONATE MEDIA FROM BOREHOLE HYDROCHEMICAL LOGGING DATA COMPARISON WITH THERMOMETRIC RESULTS

Flow rates and concentrations from fractures intersected by a borehole can be estimated by matching simulated concentration profiles to the observed variations in water chemistry along the borehole. Experiments in karstic rocks prove that hydraulic short circuits between fractures yield a very complex flow pattern, and that flow velocities in the borehole may be higher than the velocity at which the piezometric level varies. Combined temperature and concentration studies characterize flow in both high permeability channels and slightly fissured blocks, as chemical profiles detect low velocity slows that cannot be identified on temperature profiles. Such studies are there fore advisable to characterize natural flow in fractured carbonate rocks, but also in other fractured media.