A model to quantify permeability in solute mixing precipitation porous media

Abstract

The effects of the concentration and flow velocity of the solution on calcite precipitation process in porous media and its permeability were investigated with a combined experimental and modeling approach. In the column precipitation experiments, calcite precipitation was mainly distributed at the inlet of experimental column and quickly decreases along the flow direction, and precipitates completely wrapped the quartz sands at the inlet, and the gaps between the quartz sands were filled. The permeability coefficient of experimental column decreases quickly in the early stage and then decreases slowly. The calcite precipitates in the experimental column increased with the saturation index and gradually stretched along the flow direction with the flow velocity increase. The precipitates were distributed within 1.0 cm of the experimental column inlet. In the model, based on the classical Kozeny-Carman equation and the principle of series superposition, a coupled model of mineral precipitation and permeability coefficient in porous media was developed, the model was verified, and the parameter sensitivity was analyzed. It revealed that the mineral precipitation at the inlet interface of experimental column was the dominant factor determining the permeability coefficient of porous media. When considering solution conditions, the saturation indices SI and flow velocity V were the main factors affecting calcite precipitation and permeability coefficient in porous media. When the solution conditions were not considered, the quartz sand diameter ds, the length of quartz sand column L and porosityφ aiming at mineral precipitation had higher sensitivity, and the porosity ϕ aiming at permeability coefficient had higher sensitivity.