Characterization of Fluid Flow System between Injection and Production Wells by Tritium Tracer Test Analysis

摘要

Tritium tracer test was conducted for investigating the connectivity between injection and production wells in a steam-water two phase geothermal system. Injection and production wells are probably separated over a low permeability zone. A multi-path flow model adopting analytical solution of advection-dispersion of solute transport equation for one-dimensional linear flow system was used to quantitatively characterize unknown parameters. Optimum number of flow paths was determined by the least squares method with this model. A model with two flow paths was successfully fitted to the tracer return curve of production wells which have short distances between the well bottom of injection and production wells wherein mass transport mechanism is dominated by convection process as indicated by high Peclet number (Pe > 1). On the other hand, wells having long well bottom distance between injection and production wells show flow characteristics of high longitudinal dispersivity with low Pe (Pe < 1). Results of modeling were interpreted together with the geological data to estimate the possible geological structures representing the physical characteristics of the model and confirmed by well bore data.