Progress of research on key technologies for hydrogeochemical prospecting in North China type coalfield

North China type coalfield is an important coal base in China, and hydrogeochemical prospecting is an important means to solve a series of hydrogeological problems in the process of coal mining. The typical hydrogeological problems under the influence of mining were analyzed based on the generalization of the typical hydrogeological structure of North China type coalfield. Meanwhile, the multi-field coupling relationship of groundwater and the mechanism of hydrogeochemical prospecting in North China type coalfield, as well as its testing, analysis and treatment technology, were revealed. Besides, the reliability of hydrogeochemical prospecting technology in North China type coalfield was pointed out by reviewing the development history of hydrogeochemical theory. In addition, the commonly used hydrogeochemical components and the testing instruments of groundwater were summarized, and the technical means of hydrogeochemical prospecting were elaborated from graphical method, mathematical statistical method, physical simulation and numerical simulation, etc. On this basis, the progress of research on application of key technologies for hydrogeochemical prospecting under the multi-field coupling in North China type coalfield was reviewed from the aspects of groundwater resource evaluation, dynamic identification of water inrush sources, spatiotemporal evolution of hydrogeochemistry, anomaly inversion of groundwater dynamics, geological structure anomaly inversion, construction of groundwater mixed mode and hydrothermal resources exploration, etc. Hence, the superiority and operability of hydrogeochemical prospecting was clarified. Moreover, the typical technical core of hydrogeochemical prospecting in North China type coalfield was proposed in combination with the hydrogeological conditions of North China type coalfield, and the existing problems were pointed out, indicating the effort direction in the research of hydrogeochemical prospecting technology.