Outcrop and drill hole data show that the Jurassic coal measures in the northeastern Ordos Basin are composed mainly of the Yan’an Formation and the lowstand system tract of the Zhiluo Formation, and there is a regio...Outcrop and drill hole data show that the Jurassic coal measures in the northeastern Ordos Basin are composed mainly of the Yan’an Formation and the lowstand system tract of the Zhiluo Formation, and there is a regional unconformity between them. The Dongsheng uranium deposit is associated with the Jurassic coal measures. Research data indicate that the Jurassic coal measures in the study area have a certain hydrocarbon-generating capacity, although the metamorphic grade is low （Ro=0.40%–0.58%）. In the Dongsheng region alone, the accumulative amount of generated coalbed methane （CBM） is about 2028.29 × 108 –2218.72 × 108 m3; the residual amount is about 50.92 × 108 m3, and the lost amount is about 1977 × 108 m3. Analysis of the burial history of the host rocks and the evolutionary history of the Dongsheng uranium deposit suggests that the Jurassic coal measures generated hydrocarbon mainly from Middle Jurassic to Early Crataceous, which is the main mineralization phase of the Dongsheng uranium deposit. By the Late Cretaceous, a mass of CBM dissipated due to the strong tectonic uplift, and the Dongsheng uranium deposit stepped into the preservation phase. Therefore, the low-mature hydrocarbon-containing fluid in the Jurassic coal measures not only served as a reducing agent for the formation of sandstone-type uranium deposits, but also rendered the second reduction of paleo-interlayer oxidation zone and become the primary reducing agent for ore conservation. Regional strata correlation reveals that the sandstone-type uranium reservoir at the bottom of the Zhiluo Formation is in contact with the underlying industrial coal seams in the Yan’an Formation through incision or in the form of an unconformity surface. In the Dongsheng region with poorly developed fault systems, the unconformity surface and scour surface served as the main migration pathways for low-mature hydrocarbon-containing fluid migrating to the uranium reservoir.展开更多
Sandstone is a common lithology in a number of groundwater reservoirs. Studying the skeleton sandstone architectural units, therefore, lays the basis for characterizing aquifer systems, groundwater quality, and resour...Sandstone is a common lithology in a number of groundwater reservoirs. Studying the skeleton sandstone architectural units, therefore, lays the basis for characterizing aquifer systems, groundwater quality, and resource evaluation. This comprehensive analysis of Cretaceous aquiferous sandstones in the Ordos basin, China, shows that there exists a basin-scale skeleton sandstone in the Luohe Formation which contains 11 isolated barrier beds, 12 small skeleton sandstone bodies in Huanhe Formation, and 3 in the Luohandong Formation. The spatial structure and superimposed relationship as well as the medium properties of these skeleton sandstones and isolated barrier beds can be shown by 3D visualization models. Simultaneously, resource quantity can be evaluated with the 3D inquiry functions. The comparison between property models and structural models indicates that the salinity of groundwater of the Luohe Formation has a close connection with the locations of isolated barrier beds that contain abundant gypsum. Through quantitative calculation, groundwater resource of the Cretaceous Luohe and Luohandong formations is estimated to be 1.6×10-（12） m-3, and the total groundwater resource of the Cretaceous system in the Ordos basin is more than 2×10-（12） m-3.展开更多
基金sponsored by the National Natural Science Foundation Program of China (Nos.40772072 and 40802023)the Uranium Deposit Geological Program of Bureau of Geology,CNNC,the National Important Basic Research Program of China (No.2003CB214603 and No.2015CB453003)the Dongsheng coal and uranium exploration program of Central Geological exploration Fund (No.2008150013)
文摘Outcrop and drill hole data show that the Jurassic coal measures in the northeastern Ordos Basin are composed mainly of the Yan’an Formation and the lowstand system tract of the Zhiluo Formation, and there is a regional unconformity between them. The Dongsheng uranium deposit is associated with the Jurassic coal measures. Research data indicate that the Jurassic coal measures in the study area have a certain hydrocarbon-generating capacity, although the metamorphic grade is low （Ro=0.40%–0.58%）. In the Dongsheng region alone, the accumulative amount of generated coalbed methane （CBM） is about 2028.29 × 108 –2218.72 × 108 m3; the residual amount is about 50.92 × 108 m3, and the lost amount is about 1977 × 108 m3. Analysis of the burial history of the host rocks and the evolutionary history of the Dongsheng uranium deposit suggests that the Jurassic coal measures generated hydrocarbon mainly from Middle Jurassic to Early Crataceous, which is the main mineralization phase of the Dongsheng uranium deposit. By the Late Cretaceous, a mass of CBM dissipated due to the strong tectonic uplift, and the Dongsheng uranium deposit stepped into the preservation phase. Therefore, the low-mature hydrocarbon-containing fluid in the Jurassic coal measures not only served as a reducing agent for the formation of sandstone-type uranium deposits, but also rendered the second reduction of paleo-interlayer oxidation zone and become the primary reducing agent for ore conservation. Regional strata correlation reveals that the sandstone-type uranium reservoir at the bottom of the Zhiluo Formation is in contact with the underlying industrial coal seams in the Yan’an Formation through incision or in the form of an unconformity surface. In the Dongsheng region with poorly developed fault systems, the unconformity surface and scour surface served as the main migration pathways for low-mature hydrocarbon-containing fluid migrating to the uranium reservoir.
基金sponsored by the Special Fund for Geological Survey of the Central Government (No.12120115013701)the National Important Basic Research Program of China (No.2015CB453003)China Geological Survey Project (No.1212010331302ZT6)
文摘Sandstone is a common lithology in a number of groundwater reservoirs. Studying the skeleton sandstone architectural units, therefore, lays the basis for characterizing aquifer systems, groundwater quality, and resource evaluation. This comprehensive analysis of Cretaceous aquiferous sandstones in the Ordos basin, China, shows that there exists a basin-scale skeleton sandstone in the Luohe Formation which contains 11 isolated barrier beds, 12 small skeleton sandstone bodies in Huanhe Formation, and 3 in the Luohandong Formation. The spatial structure and superimposed relationship as well as the medium properties of these skeleton sandstones and isolated barrier beds can be shown by 3D visualization models. Simultaneously, resource quantity can be evaluated with the 3D inquiry functions. The comparison between property models and structural models indicates that the salinity of groundwater of the Luohe Formation has a close connection with the locations of isolated barrier beds that contain abundant gypsum. Through quantitative calculation, groundwater resource of the Cretaceous Luohe and Luohandong formations is estimated to be 1.6×10-（12） m-3, and the total groundwater resource of the Cretaceous system in the Ordos basin is more than 2×10-（12） m-3.
