(391c) Method of Moments to Characterize Porous Media Using Non-Ideal Tracer

Tracer tests are widely used to characterize the porous media such as chemical reactors, oil reservoirs, groundwater aquifers. Due to solid phase heterogeneity, tracers may behave non-ideally and can get adsorbed on the solid surface. This leads to a long tail in tracer exit age density curves. In addition to the non-ideality of the tracer, the dead-ends in the porous media also lead to long tails. Simulations are used to estimate the dead-end volume fraction of the pores, mass transfer rate into the dead end, dispersion and adsorption behavior using the tracer exit age density curves. However, the parameter matching is difficult as the problem to find process parameters given the exit age density is ill-posed and can have multiple solutions. In this work, we presents a method of moments to characterize the porous medium for the process parameters using a single exit age density curve using a non-ideal adsorbing tracer. We use behavior of higher order moments of exit age density, namely, mean, variance, skewness, and kurtosis to estimate Peclet number, dead end volume fraction, mass transfer in dead end volume and adsorption behavior of the tracer. We observe that the first moment depends only on the retardation factor, which is always greater than unity for the non-ideal tracer. Similarly, we find the affect of the dead-end volume and adsorption of tracer on the variance, skewness, and kurtosis of the residence time density curve. We use experimental results from literature to establish the usability of our method.