Non-Fickian dispersion in porous media: 1. Multiscale measurements using single-well injection withdrawal tracer tests

摘要: We present a set of single-well injection withdrawal tracer tests in paleoreef porous reservoir displaying important small-scale heterogeneity. An improved dual-packer probe was designed to perform dirac-like and accurate downhole automatic measurements the concentration during recovery phase. By flushing tracer, at constant flow rate, for increasing time duration, we can distinctly different volumes test multiscale predictability (non-Fickian) dispersion models. First describe characteristics, from microscale meter scale, rock. Second, specificity setup results obtained using two tracers measurement methods (salinity-conductivity fluorescent dye­optical measurement, respectively) are presented. All display strongly tailed breakthrough curves (BTC) consistent with diffusion immobile regions. Conductivity results, measured over 3 orders magnitude only, could have been easily interpreted by conventional mobile-immobile (MIM) diffusive mass transfer model asymptotic log-log slope 2. However, dye sensor, which allows exploring much lower values, shows that change occurs larger an value 1.5, corresponding double-porosity model. These suggest conventional, one-slope MIM rate is too simplistic account real heterogeneity diffusion-dominant fraction reservoir.