| Water damage is the main geological disaster which causes the mass casualty accidents in coal mines.It is a major scientific proposition to study the mechanism and law of the geological control of the occurrence of underground water in the coal mine and predict the distribution of the rich water area.There are many large modern mines in the bordering area of the Inner Mongolia Autonomous Region and Shaanxi.Coal production is often threatened by floods.In this paper,based on the theory of sedimentary geology,sequence stratigraphy,hydrogeology and lithofacies palaeogeography,the 3-1 coal seam(first coal seam)of the Yanan formation to the Zhiluo formation of the Uxin Banner and Hengshan region is the key layer,and the methods of field investigation,sample analysis,information integration and qualitative and quantitative combination are adopted.The sequence stratigraphy control,lithofacies palaeogeographic features and water rich geological control mechanism and regularity of hydrogeological structure in the study area are analyzed from the transport and diagenesis,and the distribution of the rich water area is predicted.The results show that:(1)There are 6 sequence boundaries in the region.The Aalenian-Baijocian sequence is divided into 3(three grade)sequences(sequence I,sequence II,sequence III),and 2(three grade)sequences(sequence IV and sequence V)in Bathonian-Callovian period,and each sequence is composed of low system tract(LST),water into system domain(TST)and high system tract(HST).Sequence III: water system tract and high system tract are poorly preserved because of erosion and upper channel erosion;sequence tracts IV and V have relatively complete tracts.The 3-1 coal seam roof to the Zhilou aquifer mainly endowed with sequence III,sequence IV,sequence V low system tract,sequence IV and sequence V water into the distributary channel.The aquifers are mainly developed in the high system tract delta plain flood plain and marsh environment.(2)Baijocian sequence II(high)+ III(low)source from NE,ancient flow to NE-SW;sequence Bathonian sequence IV and Callovian phase V phase V source from NW,paleo flow to NW-SE.The Baijocian period 3-1 coal seam to 2-2 coal seam,2-2 coal seam to 2-1 coal seam sand body is distributary channel deposit,Baijocian period "Zhenwudonge sandstone",Bathonian period "Qliizhen sandstone" and Callovian period "Gaoqiao sandstone" are deposited in river and distributary channel.(3)The aquifers in the top of the 3-1 coal seam are divided into four types: coarse grained sandstone,medium grain sandstone,fine grained sandstone and siltstone.The aquifers are divided into four types: argillaceous(powder)sandstone,sandy mudstone,silty mudstone and mudstone.The aquifer is mainly composed of pores,and the aquifer is divided into confined,medium and weakly permeable pore aquifers.The sequence II(high)+ III(low)coarse sandstone aquifers are pressurized permeable pore aquifers,and sequence II(high)+ III(low)medium grain sandstone,sequence IV,V coarse,and medium sandstone aquifers are confined medium permeable pore aquifers.Sequence II(high)+ III(low),sequence IV,V fine grained sandstone and siltstone aquifer are confined and weakly permeable pore aquifers.(4)The channel sand body separation,grinding roundness better than the distributary channel,better than the mouth fan,natural embankment,flood plain,river floodplain,effective porosity and permeability,high permeability,the same ancient river,the channel edge to the center of the effective porosity and permeability of the sand body,permeability enhancement.On the plane,the upper and lower reaches of the river are: the better the sorting and the degree of roundness,the lower the matrix content,the higher the effective porosity and permeability.(distributary)the single layer sand in the center of the river course is large in thickness,coarse in size and high in sand ratio,smaller in thickness on both sides,finer in grain size and lower in sand to ground ratio.The porosity and permeability conditions of sandstone are sequence II(high)+ III(low)> sequence IV > sequence V rule.After the diagenesis,the sandbody is homogeneous,and the pore permeability and permeability are improved.The permeability coefficient of aquifers increases exponentially with the increase of effective porosity.With the increase of effective porosity to a certain extent,the small changes in the porosity will cause a large change in the permeability coefficient,and the effective porosity has a positive linear relationship with the water content.The plastic bending deformation,directional arrangement,brittle mineral contact contact,calcareous,muddy cementation,quartz and feldspar increase in the aquifer sandstone,which make the porosity and permeability worse,the high pervious ability of the calcium content,and the dissolution of the feldspar to improve the physical property of the coal seam roof.(5)The five degree method is used to evaluate the type of rich water zone between the 3-1 coal seam and the Zhilou group,which is the strong water rich area,the stronger water rich area,the medium rich water area,the weaker rich water area and the weak rich area.The strong water rich areas are mainly distributed in the center of the paleo channel or the downstream of the distributary channel,and the strong water rich areas are mainly distributed in the center of the edge of the river or the central part of the upstream of the distributary channel,and the middle rich area is mainly distributed in the edge of the river and the upper part of the distributary channel,and the weaker water rich areas are mainly distributed on the edge of the ancient river road and the river.Floodplain,flood plain and other parts;weak water rich areas are mainly distributed in floodplain,flood plain and swamp.The prediction results proved to be correct in the 311306 working face and 311201 working face mining in Bayangaole coal mine. |
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