Bleached mudstone, iron concretions, and calcite veins: a natural analogue for the effects of reducing CO2‐bearing fluids on migration and mineralization of iron, sealing properties, and composition of mudstone cap rocks

摘要: This study investigates the Wangfu depression of Songliao Basin, China, as a natural analogue site for Fe migration (bleaching) and mineralization (formation iron concretions) caused by reducing CO2-bearing fluids that leak along fractures after carbon capture, utilization, storage. We also examined origin fracture-filling calcite veins, properties self-sealing fluids, influence on compositions mudstone, established bleaching model area. Our results show concretions are oxidative products precursor minerals (pyrite siderite) during uplift linked to H2S CO2 present in early stage fluids. The precipitation veins is result degassing related CO2, CH4, minor heavy hydrocarbons main In our model, preferentially enter high-permeability fracture systems surrounding rocks veins. infilling significantly decreases permeability forces slowly bleach mudstone rocks. Fe2+ released migrates elsewhere with solutions or re-precipitated concretions. formation reduces space effectively prevents fluid flow. have an insignificant effect within mudstone. terms chemistry only contents Fe2O3, U, Mo change significantly, content U increasing Fe2O3 decreasing bleaching. This article protected copyright. All rights reserved.