Study On The Law Of Sandstone Sedimentation Control In Luohe Group In Gaojiabao Coal Mine

Gaojiabao Coal Mine is located in the southwest margin of Ordos Basin and northwest of Binchang Mining Area.It belongs to Huanglong Jurassic coalfield.The main recoverable coal seam is 4#coal,4-1 coal and 4 upper coal.With the mining of coal seam,the water-conducting fissure zone has developed the upper overburden Luohe formation sandstone aquifer.The thickness of the aquifer is huge,which provides a good storage and migration space for groundwater,and is the main aquifer that threatens the safe production of the mine.Therefore,the study of water control law of the sandstone aquifer of Luohe group is an important part of the mine water control work.Based on the theories of geology,hydrogeology,mineralogy,mathematical geology,sedimentology and sequence stratigraphy,this paper studies the sedimentary water-controlling law of Luohe formation aquifer and a water-rich partition is carried out,by collecting relevant geological data,sampling and indoor experiments,computational processing.The findings of the study are as follows:(1)Based on the analysis of logging curves and lithologic columns,the lithofacies types in the study area are divided into 21 subclasses,and the combination of rock phases of the development of sedimentary phases in the region is discussed.(2)The sedimentary environment of the Luohe Formation in the study area is a transitional zone on the edge of desert.Sandstone of the dune has typical characteristics of desert-derived sandstone,mainly calcareous cementation,loose cementation,but by the stronger action of flowing water,the grain size is coarser.(3)On the basis of the sequence stratigraphy theory,the Luohe Formation in the study area is divided into a super-large spin back SSC1 and three large spin back BSC1,BSC2 and BSC3,each large-scale spin back into three medium-sized spin back MSC1,MSC2,MSC3.(4)The porosity and permeability of sandstone in Luohe formation are as follows:BSC2>BSC1>BSC3;in sedimentary facies are the characteristics of sand dunes>arid valleys>desert lakes.BSC2 is mainly calcareous cementation,the lithic composition is mainly quartz and feldspar,the muddy content is very little,and the pores are developed;BSC3 and BSC1 are mainly muddy cementation,the muddy content is high,the porosity connectivity is poor,and the permeability is general.(5)The new five-scale method-scale method is introduced to predict and evaluate the water-rich areas of the Luohe Formation in the minefield.