Prediction Of Qaidam Basin In Mahai Potassium Rich Brine Reservoir Characteristics And Favorable Area

Mahai Salt Lake is located in the eastern part of the Qaidam Basin,and its Quaternary strata is rich in potash.In recent years,due to large-scale development and utilization,shallow potassium-rich brine consumption is rapid,submerged water level dropped significantly,resulting in a large number of superficial solid potassium-poor ore was "overhead",the loss of the original natural state solid-liquid conversion Of the good conditions,the development and utilization of more and more difficult.It can be seen that it is important to study the reservoir characteristics of potassium-rich brine,especially deep confined water,to predict the potash-favorable area and to further realize the sustainable development of potash mineral resources in this area.Based on the field geological survey,combined with the geological stratigraphic comparison and analysis of the aquifers in the 76 boreholes in the mining area,the petrography of the pressurized brine reservoirs was studied in this paper.Research,porosity analysis and water analysis.The study shows that the Quaternary strata of Mahai Salt Lake are mainly clastic rocks and evaporite sediments.The clastic rocks are mainly composed of silt,fine sand and clay,and silt is mainly gypsum,Mainly.According to the longitudinal evolution characteristics of strata lithology in boreholes,four evaporite sedimentary cycles were identified,which were named cycles I,II,III and IV,corresponding to Holocene,Holocene-Late Pleistocene,late renewal The Middle Pleistocene,the early Pleistocene.Since the early Pleistocene,Mahai Salt Lake has mainly developed alluvial facies,lake facies,shallow lake facies and salt lake facies facies.Based on the salinity and stratigraphic thickness contour maps,the central migration of the Quaternary salt lake in the mining area is studied.The results show that the center of the ancient salt lake is mainly located in the southeast of the mining area The center of the ancient salt lake is located in the middle of the mining area,near the location of the drilling ZK7008;the cycle II late Pleistocene-Holocene,the ancient salt lake center is located in the eastern part of the study area,drilling ZK7808 near the location;cycle I Holocene stage,Salt Lake Center is located in the northeast of the study area.It can be seen that since the early Pleistocene,the ancient salt lake center in Mahai area has a tendency to migrate from the southeastern part to the eastern part of the basin,which may be related to the basin subgrade depression caused by the tectonic movement in the basin.The study of potassium-rich pressurized brine reservoirs shows that the Quaternaryhoneycombite salt and the mirabilite salt layer with honeycomb-like structure are the most important reservoirs for pressurized brine.The honeycomb rock salt rock is often overburdened and compacted massive lacustrine salt rock,such stone salt pore development is not developed,smoke gray,gray,clay or relatively pure.The honeycomb-shaped salt rock forms a complete halide-containing unit with its superficial and underlying compact lumpy salt rock and clay layers.The filling and cementation of clay and silt greatly reduced the porosity and wateriness of the stone salt rock,which indicated that the basin was stable and the area affected by the debris supply had the condition of forming the effective reservoir.Based on the characteristics of reservoir distribution and the migration process of salt lake,this paper holds that the middle part of Mahai area is the main potential area of potassium-rich brine resources,and the favorable horizon is the late-Pleistocene-Meso-Pleistocene epoch-making.The eastern part of the study area is secondary Potential area,corresponding to the stratum of the Holocene-late Pleistocene cycle ?.