The Research Of Sedimentary Facies Of The 2^nd Member Of Baikouquan Formation In The Area Of Ma131 Well,Junggar Basin

Mahu Sag is a hot area of oil and gas exploration in Junggar Basin,the Triassic Baikouquan Formation is main oil and gas exploration target.But at present,there are many questions restricting the process of exploration such as the shallow exploration degree,the controversial source direction,sedimentary facies,glutenite genesis,and so on,which makes it is necessary to do some researches of sedimentology,sequence strstigraphy and reservoir.Guiding by the geology,sedimentology and geophysics,combining with the core and logging facies,the observation and description of core,the analysis of experimental data and antecedent information,this paper defined the types of sedimentary facies and their distribution model by identification of the markers of sedimentary facies,and predicted the distribution of favorable reservoirs by analysis of the controlling factors of reservoir quality.Base on the comprehensive analysis of core,drilling and well logging data,the Triassic Baikouquan Formation belongs to one 3rd order sequence,and the target is one 4th order sequence.According to the macroscopic and microscopic observation and description of a large number of drilling cores,the lithological characteristics are summarized.The main rock types are gray and green grey glutenite,conglomerate and pebbly sandstone with coarse size and poor sorting.The mudstone is brown and green grey.In the composition,debris occupied the high range,while quartz is relatively than less,an feldspar is the least.Calcite is the main cement.Gravity flow and traction flow are the main sedimentary mechanism with strong hydrodynamic force.It has been put forward that the principal provenance in the study area mainly is from northeast direction by utilizing the variety of data comprehensively.Twelve types of core facies are identified by core analysis.According to the characteristics of single well facies & connecting well facies and facies markers,fan-delta is determined and with the obvious depositional sub facies zones.According to the evolution rules and controlling factors,the evolution pattern of sedimentary face is established.Based on the study sedimentary facies and analysis of the characteristics of reservoir rocks,physical properties and diagenesis,this study revealed that matrix content,grain size and diagenesis are the main factors controlling reservoir quality.The subaqueous distributary channel in fan delta front is the favorable reservoir in the study area.