Pearce J K, Dawson G W, Turner L, Southam G, Brink F, Paterson D, Kirste D, Golding S D
Gas and Energy Transition Research Centre, University of Queensland, QLD, Australia; School of the Environment, University of Queensland, QLD, Australia.
School of the Environment, University of Queensland, QLD, Australia.
Sci Total Environ. 2025 Jan 1;958:177993. doi: 10.1016/j.scitotenv.2024.177993. Epub 2024 Dec 11.
Carbon dioxide geological storage is proposed as part of the solution to reach net zero emissions. The potential to mobilise heavy metals to low salinity groundwater through CO water rock geochemical reactions is a potential environmental risk factor, if CO migrates. Previous studies have focused on pure CO reactivity, however CO streams from hard to abate industries can contain gas impurities. Reservoir sandstone and mudstone drill cores from a proposed low salinity CO storage demonstration site were reacted at in situ conditions with pure CO or an impure NO-SO-CO stream. Sandstones hosted Rb in illite analysed via synchrotron XFM. Arsenic (As) was hosted in pyrite; and Pb, Cr, Mn in siderite rimming intergranular pores. Mudstone contained Zn, Co, Ni, Cu, As, Pb in sphalerite, and Rb in illite and K-feldspar. In impure NO-SO-CO experiments the lowered pH and oxidising conditions initially released higher concentrations of metals including Pb, Zn, Co into solution compared to pure CO reactions. Higher concentrations of Zn (Mn and Co) were released from sphalerite in the mudstone. Fe-chlorite, K-feldspar, and carbonate dissolution released Rb, Si, Fe, Ca, and Mg. Elevated dissolved Pb was mainly from siderite and sulphide mineral reaction in sandstones. Mobilised As was released prior to CO addition from desorption and ion exchange. Clay and fines migration into pores occurred in both pure and impure CO reactions that has the potential to impact fluid migration. A portion of metals including Fe, Ni, Cr were subsequently incorporated in precipitated Fe hydr(oxy)oxides where the co-injected NO induced oxidising conditions. Rock mineral content and the injected gas mix were the main controls on metal mobilisation to formation water. Further work should investigate new gas mixtures that may be expected in storage hubs, from blue hydrogen or from direct air capture.
二氧化碳地质封存被提议作为实现净零排放解决方案的一部分。如果二氧化碳发生迁移，通过二氧化碳-水-岩石地球化学反应将重金属迁移到低盐度地下水中的可能性是一个潜在的环境风险因素。以往的研究主要集中在纯二氧化碳的反应性上，然而，来自难以减排行业的二氧化碳流可能含有气体杂质。从一个拟建的低盐度二氧化碳封存示范场地采集的储层砂岩和泥岩岩芯，在原位条件下与纯二氧化碳或不纯的NO-SO-CO流进行反应。通过同步加速器X射线荧光显微镜分析了砂岩中伊利石所含的铷。砷存在于黄铁矿中；铅、铬、锰存在于沿粒间孔隙边缘的菱铁矿中。泥岩中的闪锌矿含有锌、钴、镍、铜、砷、铅，伊利石和钾长石中含有铷。在不纯的NO-SO-CO实验中，与纯二氧化碳反应相比，较低的pH值和氧化条件最初会使包括铅、锌、钴在内的更高浓度的金属释放到溶液中。泥岩中的闪锌矿释放出更高浓度的锌（锰和钴）。铁绿泥石、钾长石和碳酸盐的溶解释放出铷、硅、铁、钙和镁。溶解态铅的升高主要来自砂岩中菱铁矿和硫化物矿物的反应。在添加二氧化碳之前，通过解吸和离子交换释放出了迁移的砷。在纯二氧化碳和不纯二氧化碳反应中都发生了粘土和细颗粒向孔隙中的迁移，这有可能影响流体迁移。包括铁、镍、铬在内的一部分金属随后被纳入沉淀的铁氢氧化物中，其中共注入的NO诱导了氧化条件。岩石矿物含量和注入的气体混合物是控制金属向地层水迁移的主要因素。进一步的工作应研究在存储枢纽中可能出现的新气体混合物，这些混合物可能来自蓝氢或直接空气捕获。
