Study On The Upper Paleozoic Source Rocks In Yanlong Area,the Southern North China Basin

Taking Upper Paleozoic source rocks in Yanlong Area of the Southern North China Basin as the study objective,this paper systematically studies the formation and lithology of the Upper Paleozoic source rock and evaluates and analyze the influence from environment to source rock through the actual surface exploration and drilling core observation combining with the plates and X-ray diffraction analysis.Main perception:(1)Benxi formation is controlled by the karstification of the base carbonate rock,mainly developed in Coastal lagoon facies;The sedimentary environment of Taiyuan formation is closely related with epicontinental sea,which belongs to tidal flat deposits;the lower part of Shanxi formation mainly develops marsh environment,while the river function increases in the upper part;Xiashihezi formation is mainly delta plain;Shangshihezi formation is also mainly delta plain,but distributary channel sandstones significantly increased,and the Pingdingshan sandstone in the upper part of this group may be a begin for a new sedimentary stage which is mainly fluvial sedimentary;Sunjiagou formation belongs to typical continental sedimentary.(2)Source rocks mainly develop in the lower formation of Carboniferous-Permian: the lower part of Benxi formation,Taiyuan formation,and Shanxi formation(II1 coal)are continuous.Mudstone,coal,and limestone contain high organic carbon,which are good source rocks,and the organic matter type is mainly Type III.The organic carbon of the Taiyuan formation is very high,and the organic matter is type III.The overall contents of organic matter in the formation above the upper part of Shanxi formation are very low and cannot reach the standard of source rocks.The high evolution degree of this set of source rock and low hydrocarbon generation potential is probably connected with the heating catalysis of the anomaly high hot flow and pozzolanic matter caused by abstraction at the beginning of Carboniferous-Permian sedimentary.(3)The organic carbon content of coals and carbonate rocks are high,but the content of mudstones in the source rock is quite different.The tidal flat facies mudstones and swamp facies mudstones with high organic carbon content are influenced by the transgression.Due to weathering or decomposition of organic matter,the content of organic carbon is very low in the lagoon facies mudstones.Mudstones of the lower delta plain and the upper delta plain is probably affected by the river,and the organic carbon content is low.The early Paleozoic of Yanlong Area is affected by sudden transgression,and later affected by the river action.The development of source rocks mainly concerns position.The east and north part of the research area are the main favorable areas of the Carboniferous-Permian source rocks distribution.