Study On Sequence Stratigraphic Correlation And Sedimentary System Of The Lower Jurassic Badaowan Formation In The Fukang Fault Zone And The Northern Margin

The Fukang fault zone and its northern margin are rich in coal resources and coalbed methane resources,with a predicted coal resource of 8.4 billion tons and a predicted coalbed methane resource of about 45 billion m~3.The Baiyanghe well area and CSD well area in the middle of the Fukang fault zone are the first to obtain the breakthrough of China's medium-low coal rank coalbed methane industrialization.Now more than 100 coalbed methane production wells have been drilled,with an annual production capacity of 60 million m~3,effectively alleviating Urumqi is currently in a state of shortage of natural gas.However,due to the fact that the predecessors did not elaborate on the sequence and sedimentary study of the Fukang fault zone and its northern margin,the sequence stratigraphic correlation,sedimentary evolution law and coal accumulation law are unclear,which seriously restricts the progress of the subsequent resource exploration and development work in the study area..Based on this,this study takes the Fukang fault zone and the Lower Jurassic Badaowan Formation in the northern margin as the research object,guided by high-resolution sequence stratigraphy and sedimentology theory,drilling core,logging,and logging.Based on the seismic data,the study of sequence stratigraphy and sedimentary systems in the area was carried out.The isochronous stratigraphic frameworks in the area were established and the stratigraphic correlation of the whole area was carried out to identify the sedimentary systems in the area.The law of sedimentary evolution is clarified under the isochronous stratigraphic framework,and the law of coal seam distribution is revealed.Finally,the coal accumulation law is summarized.Based on the analysis and comparison of lithology,color,sandstone mark,coal seam mark and paleontological characteristics,through the identification of the sequence interface,a comparison plan for the quasi-south-eastern Badaowan Formation was established.This sequence division scheme allows for a good comparison between the drilling profiles throughout the region.In the early Early Jurassic,there were sedimentary features that were filled in and filled out and overturned.The typical sedimentary facies sequence was established by field outcrop section observation and core description,and four sedimentary systems of braided river,shallow lake,deep lake-semi-deep lake and marsh were identified.The main coal-enriched environment was the braided river triangle plain-front Marginal marshes are most developed.The sedimentary evolution of the study area can be summarized as four stages:filling and filling period,first coal accumulation period,coal accumulation migration period and continuous water intake period.The slope-break zone,the lake level and the sedimentary environment jointly control the coal-collecting mode of the area.The first-level structure in the basin and the structural bulge in the periphery jointly control the paleo-geographical pattern of the quasi-south-east and determine the location of the rich coal belt.Extend the direction.The slope zone and the fault zone in the basin determine the basic characteristics of the sedimentary system and the location and development of the coal-rich center.Finally,four coal gathering centers in Shagou,Baiyang River,Coal Ring and Xigou were formed in the Fukang mining area.