Three dimensional distribution characteristics of water-richness of main water flling aquifers based on continental sedimentary

The northern Ordos Basin belongs to the Mesozoic continental deposit,which is controlled by the factors such as strong rainfall infiltration in Maowusu D esert and large water storage space of loose layer.In the deep buried coalfield area adjacent to Inner Mongolia and Shaanxi,the main water flling aquifer of coal seam「 oof with " high water pressure,large water volume and uneven water rich" has been formed.In order to find out the spatial distribution characteristics of water abundanc e of the aquifer,taking the No.2 Coal Mine of Nalinhe as the research object,the sequence stratigraphic framework,rock particle size distribution,sand and mudstone spa tial distribution were studied using sedimentary facies analysis method,and the three-dimensional structural characteristics of the roof water bearing layer of the workin g face were detected by audio frequency electric penetration technology,and the geophysical exploration results were carried out using the underground drainage boreh oles inspection and verification.The results showed that Zhenwudong sandstone was developed in the middle and upper part of the third member of Yan'an formation,wi th a thickness of5.0 ~ 20.0 m and good continuity.The first member of Zhiluo formation was parallel unconformity on the Yan'an formation,with a thickness of 70.0 ~ 9 0.0 m.The Qilizhen sandstone at the bottom of Zhiluo formation was 5.0 ~ 23.0 m thick,with good continuity and low value on the natural gamma curve.The sandstone aquifers of Yan'an formation and Zhiluo formation were controlled by fluvial facies deposition,and the water abundance was distributed in strips.The third member of Ya n'an formation was distributed along NE-SW direction,and the water abundance was gradually weakened from southeast to northwest; the first member of Zhiluo formati on was distributed along the north-south direction,and the sand to land ratio in the center of the ancient channel is 0.4 ~ 0.7.The water abundance was gradually weak ened from northwest to southeast,and the water abundance in the middle of the mine was relatively strong. The aquifer rich areas of Yan'an formation and Zhiluo formati on were distributed in northwest southeast and northeast southwest.The overall water yield of Zhiluo formation was stronger than that of Yan'an formation,and has verti cal connectivity with Yan'an formation aquifer.In the key abnormal area determined by audio frequency electric penetration three-dimensional detection,the water inflow( > 100 m3/h) and water pressure of 31101 working face roof are relatively large,and the distribution characteristics of water abundance of roof aquifer in 31116 working fa ce are also consistent with the results of geophysical exploration,which proves that there are regional differences in water abundance of coal seam roof aquifer within th e scope of No.2 Minefield of Nalinhe,and there is also water rich difference of aquifer within the scope of single working face normal area.