Kong Zhihan, Wang Guangcai, Li Qingyu, Zhao Quansheng, Hu Shuya
School of Environmental Science and Engineering, Qingdao University, Qingdao, 266100, Shandong, China.
Sci Rep. 2024 May 11;14(1):10778. doi: 10.1038/s41598-024-61196-y.
In the late stage of underground brine mining in salt lakes, the method of injecting fresh water is often used to extract the salt from the brine storage medium. This method of freshwater displacement breaks the original water-rock equilibrium and changes the evolution process of the original underground brine. To explore the mechanism of salt release in saline water-bearing media under conditions of relatively fresh lake water dissolution, this paper analyzes the changes in the chemical parameters of brine from 168 sampling points in the Mahai salt lake in the Qaidam Basin at three stages (before exploitation, during exploitation, and late exploitation) by correlation analysis, ion ratio analysis, and other methods and investigate the variations in porosity and the evolution laws of brine. The results show that the changes in the main ion content and brine mineralization during the exploitation process are small. The changes in Ca content are significant due to the low solubility of calcium minerals, the precipitation of gypsum during the mixing process, and the adsorption of cations by alternating with Ca. Primary intergranular pore skeletons are easily corroded to form secondary pores, which increase the geological porosity. Na and Cl are the dominant ions in the brine in the study area, but the concentration of Ca2 + decreased significantly under the influence of mining, by 41.7% in the middle period and 24.5% in the late period. The correlation between Ca and salinity changes significantly in different mining stages, and the reason for the decrease of Ca may be due to the influence of mineral dissolution, mixing, and anion-cation exchange. The porosity of the layer in the study area showed the opposite trend of Ca, and the porosity increased first and then decreased. The innovation of this paper lies in analyzing the reasons and mechanisms of the disturbance of artificial dissolution mining on stratum structure by comparing the hydrochemical characteristics and porosity of underground brine storage media in three different mining stages. The research in this paper provides a theoretical basis for the calculation of brine resource reserves and the sustainable development of underground brine in salt lake areas.
在盐湖地下卤水开采后期，常采用注入淡水的方法从卤水储存介质中提取盐分。这种淡水置换方法打破了原有的水岩平衡，改变了原生地下卤水的演化过程。为探究相对淡水湖水溶解条件下含盐含水介质中盐分释放的机制，本文通过相关性分析、离子比分析等方法，分析了柴达木盆地马海盐湖168个采样点在开采前、开采中、开采后期三个阶段卤水化学参数的变化，并研究了孔隙度的变化及卤水的演化规律。结果表明，开采过程中主要离子含量和卤水矿化度变化较小。由于钙矿物溶解度低、混合过程中石膏沉淀以及钙交替吸附阳离子，钙含量变化显著。原生粒间孔隙骨架易被腐蚀形成次生孔隙，增加了地质孔隙度。钠和氯是研究区卤水中的主要离子，但在开采影响下，Ca2 +浓度显著降低，中期降低41.7%，后期降低24.5%。不同开采阶段钙与盐度的相关性变化显著，钙含量降低的原因可能是矿物溶解、混合以及阴阳离子交换的影响。研究区地层孔隙度与钙呈现相反趋势，孔隙度先增大后减小。本文的创新之处在于通过比较三个不同开采阶段地下卤水储存介质的水化学特征和孔隙度，分析人工溶解开采对地层结构扰动的原因和机制。本文的研究为盐湖地区卤水储量计算及地下卤水的可持续开发提供了理论依据。
