Research On Sedimentary Facies Of Coal-bearing Strata In Early-middle Permian In Yuzhou Henan Province And Region Coal Accumulation Characteristics In Lower Shihezi Formation

The studied area is based on the Yuzhou in Henan Province and the South Huabei basin,involving the southeastern margin of the Ordos Basin and the southwestern margin of the Qinshui Basin.The main stem of the study is the sedimentology.It analyses the characteristics of coal bearing coal in the Lower Shihezi Formation,the coal accumulation law and the main controlling factors of coal accumulation,and provides guidance for the exploration of coal bed gas and shale gas in the future.On the basis of the work done by the predecessors,this paper has collected the drilling data and other monographs and documents in Yuzhou and the surrounding area of Henan Province,according to the outcrop,rock sample and thin film under the mirror,selecting the field outcrop of the Yuzhou wind mouth as the key measured profile,and studied the sedimentary system and the sedimentary class synthetically.The temporal and spatial variation of sedimentary facies in the Yuzhou and its surrounding areas in Henan Province is analyzed.The characteristics of the coal seam,the change of the regional coal bearing characteristics,the characteristics of the coal accumulation and the related sedimentary facies.the well map and the thickness map of the coal seam are discussed.The law of coal accumulation and main controlling factors of coal accumulation in Lower Shihezi Formation in Yuzhou area,Henan are discussed.Applying modern sedimentology theory,the sedimentary facies and submicrofacies of Taiyuan formation,Shanxi formation and Lower Shihezi Formation in Yuzhou,Henan,are analyzed in detail,and the sedimentary facies are divided into epicontinental sea,lagoon Bay and delta plain.The Taiyuan formation in this area is a land surface sea deposit,the bottom is a carbonate platform and a set of tidal flat clastic rocks that are sandwiched in the middle,with the bottom of the Shanxi formation being the lagoon Bay facies,the tidal flat and the peat swamp are mainly the delta plain facies,and the estuarine dam,the distributary channel and the flood basin are developed.The top water is deepened and the lake facies is deepened to the lake facies.The bottom of the Lower Shihezi Formation,being a delta plain,is deposited in the Shanxi formation,which is a lacustrine facies,a distributary channel-a distributary Bay-overflow basin,which is a cycle of this sedimentary model in the delta plain.The well map and lithofacies paleogeographic map of the studied area are drawn,and focus lies on the coal bearing strata in the Lower Shihezi Formation.In the delta plain of the area,due to the increase of bifurcations of distributary channels and the development of distributary Bay,only some unstable thin coal seams are formed,and only three 9 can be exploited.However,in the southeastern part of Yuzhou,the delta distributary Bay becomes more open,and after filling and silting,a larger distributary swamp can be formed.The partially abandoned deltaic body and the broad Bay edge environment are also conducive to the extensive development of coal accumulation.The number of coal beds is numorous,the thickness is large,and it is more stable.The main coal gathering environment in the study area is the peat bogs in the diverting Bay,and the coal gathering environment of the peat flat is not developed.With the continuous advance of the Delta,the scope of coal accumulation is also increased.The main controlling factors of regional coal accumulation,such as sedimentary environment and paleoclimate,are analyzed and summarized.