Investigation of the hydraulic conductivity and advancement rule in an annular effective heterogeneous aquifer around an injection single well

Hydraulic conductivity exhibits dynamic circular and annular distributions within the porous media of the sweeping zone and surrounding contaminated groundwater. Investigating the equivalent hydraulic conductivity in annular effective heterogeneous media is essential for simplifying the calculation of hydraulic parameters. This study generalized the flow of a polymer mixture and contaminated plume in an aquifer as radial flow with differing hydraulic conductivities: K P (with respect to the polymer mixture) and K W (with respect to water). A theoretical formula for the equivalent hydraulic conductivity of annular effective heterogeneous media and corresponding methods for calculating key hydraulic parameters were developed. Radial transport experiments demonstrated that the experimental results for equivalent hydraulic conductivity, actual average radial velocity, and the time required to reach the influence radius were in good agreement with the theoretical predictions. As the radial advancement radius increased, the equivalent hydraulic conductivity gradually decreased, transitioning from the hydraulic conductivity of a medium with respect to water ( K W ) to that with respect to a polymer mixture ( K P ). Higher concentrations of the polymer mixture reduced the hydraulic conductivity contrast ( K P / K W ), thereby further decreasing the equivalent hydraulic conductivity of the aquifer layer. The actual average radial velocity and the time required to reach the influence radius were controlled by the radial advancement radius, the polymer mixture concentration, and the hydraulic head difference. These three factors influenced the change in displacement resistance during single-well injection. Finally, the reliability and simplicity of the theoretical formula and hydraulic calculation method were confirmed. This work facilitates the design of single-well injection remediation schemes for in situ chemical remediation of groundwater contamination.