Xinjiang Petroleum Geology ›› 2007, Vol. 28 ›› Issue (5): 579-584.

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Mechanism of CO2-Sandstone Interaction and Formative Authigenic Mineral Assemblage

GAO Yu-qiao, LIU Li, QU Xi-yu   

  1. College of Earth Sciences, Jilin University, Changchun, Jilin 130061,China
  • Received:2006-11-01 Revised:2006-12-11 Online:2007-10-01 Published:2020-08-03

Abstract: When CO2 is injected into aquifer sandstone by natural or manual mode, diagenetic fluid will become weak acidic fluid, resulting in the decomposition of unstable minerals such as carbonate and feldspar and the precipitation of new minerals in host sandstone as well as the variation of sandstone porosity and permeability and formation water geochemical characteristics. Moreover, only a small amount of CO2 dissolves in water as a form of gas, while most of it is solidified in the host sandstone in forms of secondary minerals like calcite, dolomite and siderite, etc. The typical authigenic mineral assemblages include the dawsonite ±ferruginous carbonate ±other carbonate and the ankerite + kaolinite + authigenic quartz ones, in which the former is a typical authigenic mineral assemblage to trace CO2 migration and accumulation. This study on mechanism of CO2-sandstone interaction and formative authigenic mineral assemblage not only broadens the field of fluid-rock interaction in sedimentary basins, reveals the mass transportation between deep fluid and upper reservoir or between shallow source rock (or other rocks) and adjacent reservoir rocks, but also provides basic geologic information for the researches of sandstone reservoir quality evaluation, CO2 gas pool (or field) prediction and CO2 subsurface storage.

Key words: CO2, sandstone, interaction, mechanism, authigenic minerals

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