摘要
鄂尔多斯盆地分布有黄陇、陕北、神东、宁东4个煤炭基地,主要开采侏罗系延安组煤层,顶板水害是区内煤矿开采的主要灾害,直罗组是主要突水水源之一。为研究直罗组含水层富水性特征,采用地学信息系统编图、微观孔隙结构测试与统计分析等手段,分析了直罗组含(隔)水岩组空间赋存特征,微观孔隙结构特征及其与富水性的关系。结果表明:受沉积环境的控制,直罗组可分为上、中、下3段,主要含水岩组为风化基岩段,粗粒砂岩、中粒砂岩和细粒砂岩段,主要隔水岩组为粉砂岩、砂质泥岩和泥岩段。风化基岩含水层段主要位于基岩顶部3.04~83.46 m,呈南北向条带状分布于研究区中部,风化基岩厚度和风化程度从中部向南北两侧逐渐变薄和减弱;直罗组下段砂岩含水岩组厚度、砂地比明显大于中上段,且下段砂体展布形态呈现出泛连式,连续性明显好于中上段;直罗组下段隔水岩组累计厚度、层数明显小于中上段,中上段含(隔)水岩组非均质性明显强于下段;对于直罗组正常基岩而言,直罗组中上段砂岩孔隙度类型以低孔为主,渗透率类型以超低渗~特低渗为主。直罗组下段砂岩孔隙度类型以中孔为主,渗透率类型以中渗为主,相比中上段,下段孔隙度和渗透率较大。直罗组遭受风化后,岩石微裂隙明显发育,相比正常基岩,风化基岩孔隙度和渗透率较大,孔隙度类型总体以中-高孔为主,渗透率类型以中-高渗为主,储水空间相比正常基岩较发育。通过分形理论将直罗组砂岩孔隙结构类型划分为4类,直罗组下段主要以I类孔隙为主,中上段以Ⅱ,Ⅲ和Ⅳ类孔隙为主;根据Pearson系数法相关性分析结果,直罗组下段砂体厚度、直罗组下段砂地比以及直罗组下段隔水岩组厚度从宏观尺度上对直罗组富水性具有明显的控制作用,下段是直罗组富水性的主要“贡献”层段,根据3项指标将直罗组下段砂体分为3级;通过典型钻孔直罗组下段孔隙结构与富水性之间关系的分析,孔隙结构从微观尺度上对直罗组下段富水性具有一定的控制作用,微观孔隙越发育,富水性越好;通过相关性分析和抽水试验数据对比发现,风化作用使得直罗组下段砂体富水性明显增强,直罗组下段风化砂体厚度和风化程度对风化基岩富水性控制作用较为明显;通过层次分析法对直罗组下段富水性进行了评价,基岩风化区富水性总体强于未风化区域,一级砂体区域富水性强于二级砂体及三级砂体区域。
There are four coal bases in the Ordos Basin,namely Huanglong,Northern Shaanxi,Shendong and Ningdong,in which the Jurassic Yan’an Formation coal seams are mainly mined.Roof water damage is the main disaster of coal mining in the area.The Zhiluo Formation is one of the main water inrush sources.In order to study the water-rich characteristics of the aquifers in the Zhiluo Formation,the spatial occurrence characteristics of the aquifers in the Zhiluo Formation,the characteristics of the microscopic pore structure and their relationship with water richness were analyzed by means of geoscience information system mapping,microscopic pore structure testing and statistical analysis.The results show that controlled by the depositional environment,the Zhiluo Formation can be divided into upper,middle and lower members.The main water-bearing rock groups are weathered bedrock sections,coarse-grained sandstone,medium-grained sandstone and fine-grained sandstone sections.The main water-blocking rock groups are siltstone,sandy mudstone and mudstone sections.The weathered bedrock aquifer section is mainly located at 3.04-83.46 m at the top of the bedrock,and distributed in the middle of the study area in a north-south strip.The thickness and weathering degree of the weathered bedrock gradually thins and weakens from the middle to the north and south sides.The sandstone water-bearing formation thickness and sand-to-formation ratio of the lower member of the Zhiluo Formation are obviously larger than those of the middle and upper members,and the sand body distribution shape of the lower member shows a general connection type,and the continuity is obviously better than that of the middle and upper members.The cumulative thickness and number of layers of the water-blocking rock group in the lower member of the Zhiluo Formation are obviously smaller than those in the middle and upper member,and the heterogeneity of the water-blocking rock group in the middle and upper member is obviously stronger than that in the lower member.For the normal bedrock of the Zhiluo Formation,the sandstones in the middle and upper members of the Zhiluo Formation are dominated by low porosity and ultra-low permeability to ultra-low permeability.The sandstone in the lower member of the Zhiluo Formation is dominated by mesoporosity,and the permeability is dominated by medium permeability.Compared with the middle and upper members,the lower member has higher porosity and permeability.After the Zhiluo Formation was weathered,the rock micro-fractures developed obviously.Compared with the normal bedrock,the weathered bedrock has higher porosity and permeability.The porosity type is mainly medium-high porosity,and the permeability type is medium-high permeability.Mainly,the water storage space is more developed than the normal bedrock.The pore structure types of the Zhiluo Formation sandstone are divided into four types by fractal theory,the lower member of the Zhiluo Formation is mainly composed of type I pores,and the middle and upper members are mainly type II,III and IV pores.According to the correlation analysis results of the Pearson coefficient method,the sand body thickness of the lower member of the Zhiluo Formation,the sand-to-ground ratio of the lower member of the Zhiluo Formation,and the thickness of the water-blocking rock formation in the lower member of the Zhiluo Formation have obvious control effects on the water-richness of the Zhiluo Formation on the macro scale.It is the main“contributing”interval of the water-rich Zhiluo Formation.According to three indicators,the sand bodies of the lower member of the Zhiluo Formation are divided into three grades.Through the analysis of the relationship between the pore structure and water richness of the lower Zhiluo Formation in typical boreholes,the pore structure has a certain control on the water richness of the lower Zhiluo Formation from the microscopic scale.The more developed the microscopic pores,the better the water richness.Through the correlation analysis and comparison of water pumping test data,it is found that weathering makes the water richness of the sand bodies in the lower part of the Zhiluo Formation significantly enhanced,and the thickness and degree of weathering of the weathered sand bodies in the lower part of the Zhiluo Formation have obvious control effects on the water richness of weathered bedrocks.The water richness of the lower member of the Zhiluo Formation is evaluated by the method of AHP.The water richness of the weathered bedrock area is generally stronger than that of the unweathered area,and the water richness of the first-grade sand body area is stronger than that of the second-grade sand body and the third-grade sand body area.
作者
孙魁
苗彦平
陈小绳
王宏科
范立民
杨磊
马万超
路波
李成
陈建平
高帅
SUN Kui;MIAO Yanping;CHEN Xiaosheng;WANG Hongke;FAN Limin;YANG Lei;MA Wanchao;LU Bo;LI Cheng;CHEN Jianping;GAO Shuai(Key Laboratory of Mine Geological Hazards Mechanism and Control,MNR,Shaanxi Institute of Geo-Environment Monitoring,Xi’an 710054,China;School of Geology and Environment,Xi’an University of Science&Technology,Xi’an 710054;Hongliulin Mining Co.,Ltd.,Shaanxi Coal Group,Shenmu 719300,China;Northern Shaanxi Mining Co.,Ltd,,Yulin 719300,China;School of Mines,China University of Mining and Technology,Xuzhou 221116,China)
出处
《煤炭学报》
EI
CAS
CSCD
北大核心
2022年第10期3572-3598,共27页
Journal of China Coal Society
基金
陕西煤业化工集团有限公司2020年度重点科研资助项目(2020SMHKJ-B-J-27)
陕西省自然科学基础研究计划-陕煤联合基金重点资助项目(2019JLZ-03)
国家重点研发计划资助项目(2019YFC1805400)
关键词
含(隔)水层赋存特征
富水性
直罗组
鄂尔多斯盆地北部
微观孔隙结构
occurrence characteristics of containing(separated)water layers
water-rich
Zhiluo Formation
Northern Ordos Basin
microscopic pore structure
