Changes in the water permeability coefficient of the metegero-ichersky aquifer within the Mirny kimberlite field (Yakutia)

Abstract

Introduction: The Metegero-Ichersky aquifer forms 90% of the total volume of drainage water in the section of the mining of the main deposits of the Mirny kimberlite field, the Internationalnaya and the Mir pipes. The reservoirs of the Metegero-Ichersky aquifer are also used for the re-injection of brine into the Earth's interior. For this reason, the study of changes in the filtration characteristics of this area within the overall Mirny kimberlite field is an important goal that has to be achieved for the full development of the Internationalnaya and Mir deposits to the full depth of the discovered reserves. Methodology: To study the filtration characteristics and to calculate the water permeability coefficient, we conducted calculations and analysis throughout the entire observation network that consisted of 131 wells. We used observations from monitoring that was performed as well as the results of single and cluster pumping tests performed over the past 20 years. We processed and analysed over 500 groundwater inflow tests and over 50 thousand groundwater level surveys performed throughout the entire regime network. Results and discussion: As a result, we obtained information on the changes in the water permeability coefficient within the studied area. A brief hydrogeological description of the Metegero-Ichersky aquifer and the circulating natural brines was presented. We created a map of the changes in the water permeability coefficient. We studied the aspects and special features of the influence of tectonic disturbances on the hydrodynamic and capacity properties of the reservoirs of the Metegero-Ichersky aquifer. Areal zoning was performed, and individual zone blocks were defined. Conclusions: The conducted work allowed studying the changes in the coefficient of water permeability within the Mirny kimberlite field and to specify the hydrogeological conditions of the area. The dynamic effect of deep faults leads to the formation of an increased fissure displacement of the rocks in the area of study. It is related to multiple tectonic disturbances producing feathering and it leads to the formation of linear zones with increased filtration parameters. The identified pattern is taken into account during the construction of re-injection sites as well as during their expansion, when boring new wells, and searching for additional promising re-injection areas.