Geochemical element mobilisation by interaction of Bowland shale with acidic fluids
Geochemical element mobilisation by interaction of Bowland shale with acidic fluids
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DOI：
10.1016/j.fuel.2020.119914
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发表时间：
2021-04
期刊：
影响因子：
7.4
通讯作者：
Yukun Ji;J. Hennissen;E. Hough;Veerle Vandeginste;Veerle Vandeginste
中科院分区：
文献类型：
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作者：
Yukun Ji;J. Hennissen;E. Hough;Veerle Vandeginste;Veerle Vandeginste
水力压裂被广泛应用于开发非常规油气资源、加强地热能的开发以及通过地下储存捕获的二氧化碳来帮助固碳。水力压裂液通常是酸性的，会导致矿物溶解和元素解吸，从而导致地下水污染。通过间歇反应器实验研究了模拟压裂液与英国石炭纪Bowland-Hodder单元盆地页岩两个端元组成的相互作用，考察了温度、流体酸度和岩液比条件对压裂液相互作用的影响。结果表明，流体酸性主要受黄铁矿的氧化溶解和方解石的溶解控制，影响主量元素和微量元素的活动性和去向。方解石和黄铁矿的溶解分别显著地控制了锶和砷的浸出。一般而言，由于矿物溶解和离子解吸作用的增强，流体酸度和温度的升高有利于元素的活化，而较高的岩液比(碳酸盐矿物质量较高)则提高了缓冲能力，并可能通过吸附和沉淀促进某些金属离子(如Ba、Pb、Fe、Al和Mn)的固定。此外，流体-岩石相互作用后抛光页岩样品中不同矿物的表面形貌表明，矿物组成对决定孔隙结构可能起到重要作用。这项研究确定了压裂液中地球化学元素(包括污染物)在一系列流体化学和环境条件下的化学反应路径，并有助于评估不同矿物类型的页岩油藏中元素的动员情况。
Hydraulic fracturing is widely used to exploit unconventional hydrocarbon sources, to enhance exploitation of geothermal energy and to aid in carbon sequestration through underground storage of captured C O 2. The hydraulic fracturing fluids, which are commonly acidic, cause dissolution of minerals and desorption of elements which can lead to groundwater contamination. Batch reactor experiments were conducted to explore the interaction of simulated fracturing fluids with two end member compositions of basinal shales of the Bowland-Hodder unit (Carboniferous, UK) whereby the impact of temperature, fluid acidity, and rock/fluid ratio conditions were investigated. The results demonstrate that the fluid acidity is mainly controlled by the oxidative dissolution of pyrite and the dissolution of calcite, impacting mobilisation and fate of major and trace elements. The dissolution of calcite and pyrite significantly dominates the leaching of Sr and As, respectively. Generally, increased fluid acidity and temperature facilitate element mobilisation due to enhanced mineral dissolution and ion desorption, whereas higher rock/fluid ratio (higher mass of carbonate minerals) raises the buffering capacity and may promote the immobilisation of some metal ions by adsorption and precipitation (eg Ba, Pb, Fe, Al, and Mn). Moreover, the surface topography of different minerals in polished shale sample sections after fluid-rock interaction indicates that mineralogical compositions may play an important role in determining the pore structure. This research identifies chemical reaction pathways of geochemical elements (including contaminants) in fracturing fluids over a range of fluid chemistries and environmental conditions, and helps to evaluate element mobilisation from shale reservoirs with differing mineralogies.