浅层储能咸水介质空间结构演化过程研究

Few theoretical researches have probed into the heterogeneous evolution of aquifer medium space structure during the brackish aquifer energy storage due to the particularity of complex water quality, geological structure and mineral composition of brackish aquifer..A series of controllable infiltration simulation experiment is conducted in the project, which, combining with related theories of colloid and surface chemistry, explicates, in meso scale, the induced mechanism that gives rise to the aquifer medium micro-nano particles redistribution in different modes, and then probes into the variation of the brackish aquifer medium pore structure in complex space-time conditions. A three-dimension particle filter numerical model is established in connection with the heat and mass transfer theory in porous media. The permeability model correlating to the micro-nano particle concentration change in brackish aquifer energy storage process is confirmed according to the experiment results. The project makes a three-dimension infiltration sand box simulation experiment, and tries, by fixing and switching the locations of pumping well and injection well, to discover the formation mechanism and region of low permeability curtain in aquifer medium under different physicochemical conditions with variation of recharge solution..The research is made in the process of cycle coupling of micro-nano particles redistribution as well as the variation of the brackish aquifer medium space structure, for the purpose of accurately mastering the operation law of brackish aquifer energy storage and recovery system, avoiding the internal blockage phenomenon in aquifers, and offering theory reference for the formulation of reasonable brackish aquifer energy storage operation model.

由于地下咸水层复杂的水质条件以及地质结构与矿物构成的特殊性 ，当前缺乏对咸水层储能过程中含水介质空间结构非均质性演化过程的理论研究。.项目通过可控物理模拟试验，基于胶体与表面化学相关理论，从介观尺度揭示不同储能模式下引起含水介质微纳米颗粒重新分布的诱导机制，探索在复杂时空条件下咸水层孔隙结构的变化规律。在此基础上，结合多孔介质传热、传质理论，建立地下咸水层颗粒迁移模型。根据试验结果，确定咸水层储能过程中与含水介质微纳米颗粒浓度变化相关联的渗透率模型。开展三维砂箱物理模拟试验，在抽-注井固定与调换模式下，针对不同回灌溶液物理化学条件 ，探索垂直于地下水流方向的低渗透帷幕带的形成机制与区域。.通过对储能过程中地下咸水介质微纳米颗粒重组与含水层空间结构演化的循环耦合过程展开研究，力求准确掌握储能系统的运行规律，为防止储能过程中出现含水层内部堵塞现象以及制定合理的储能运行模式提供理论参考。

通过一维水平砂柱试验，结合多孔介质传质理论，从孔隙尺度探索回灌溶液温度与盐度以及含水层中微纳米颗粒形貌特征与其释放、运移、沉积过程的内在关联，揭示颗粒重组的力学诱导机制。研究结果表明，在渗流溶液水动力作用与物化性质相同，球形硅微粉释放率最高，咸水层原砂释放率最低。在试验研究基础上，结合多孔介质传热、传质理论，建立地下咸水层颗粒迁移模型。对所建立的双沉积位动力学模型进行反演，计算得到咸水层原砂在受运移距离控制点位沉积系数最大，高于人工制备砂样2个量级。结合电镜扫描与颗粒表面ζ电位测试结果，基于颗粒受力平衡分析，渗流剪切应力与颗粒法向截面面积成正比；同时伴随微纳米颗粒形貌、构成的变化，扩散双电层排斥力存在显著差异。因此，球状硅微粉颗粒通常以单体形式脱离多孔介质表面；片状次生黏土矿物颗粒多以大体积粒团形式释放，出现再次沉积或被孔喉捕获的机率提高。.通过开展可控三维物理模拟试验，探索复杂时空条件下咸水层孔隙结构变化规律；确定不同储能模式下低渗透帷幕带的形成区域。研究结果得到，回灌溶液温度、盐度变化是打破颗粒间受力平衡，造成含水介质渗透性能下降的诱导机制。在抽-注井固定与调换模式下，经历完整储能周期，含水层整体相对渗透率k/k0均出现下降，表明由微纳米颗粒物质重组导致含水介质空间结构变化具有不可逆性。针对耦合咸水层抽-灌井式土壤源热泵系统，基于多孔介质传热、传质理论以及有限长线热源模型，建立地埋管换热器井孔热-渗耦合数学模型。通过模拟计算得到，随着抽-灌水量增大，地埋管井群换热能效系数提高，井群下游区域热影响范围扩大。