| The Southern Sichuan Basin could be divided into Jiulong Mountain anticline structural belt,Chixi depression,Tongnanba anticline structural belt and CangxiBazhong low and steep structural belt,which has a long history oil and gas exploration.According to the record of industrial gas wells,the Feixianguan Formation has excellent hydrocarbon potential.However,due to the lack of Feixianguan Formation outcrops,the high accuracy isochronous stratigraphic framework un established spatial change,which lead to the research of the plate margin geometry evolution,internal structure sedimentary system and it's spatial change on basic of high accuracy isochronous stratigraphic framework is relatively locked.This paper take out of research about the sedimentary of plate margin in Yuanba region in Feixianguan Formation Northeast Sichuan baisin,combined with previous data and drilling data,the research of wavelet transform and Fischer plots had been taken out,which inored to establish the high accuracy isochronous stratigraphic framework,analyzed the structure sedimentary system and it's spatial deposion and oolitic types of spatial evolution,get the following conclusions and understanding:(1)Feixianguan formation can be divided into SQ1 and SQ2 two three order sequences and two sequences were lack of low system tract,composed of high systems tract and transgressive system tract,the exposure unconformity surface and lithology transformation surface of two kinds of sequence interface had been identified in in Yuanba region in Northeast of Sichuan.The first and second part of Feixianguan Formation is SQ1,the third and fourth part of Feixianguan Formation is SQ2.In the constrained seismic and drilling data,to carry out the division of hi-stratigraphy sequence combined with wavelet transform and Fischer diagram under the constraints of work and comparison,aimed to fill and level up the Kaijiang-Liangping trough during the SQ1 period,sedimentary thickness of continental shelf facies zone other than the two phase region,hi-frequency sequence development is not the equilibrium,the carbonate platform in Guangyuan formation,hi-frequency sequence development more balancedduring the SQ2 period.Overall that comprehensive analysis of two methods of composite can effectively carry out the high resolution sequence stratigraphy,but Fischer in different phase difference position structure is obvious,for the selective application with different phase.(2)Based on the seismic and drilling data,outcrop comprehensive analysis,carried out in sedimentary facies of Guangyuan area in Feixianguan formation,can be identified out of restricted platform,open platform,platform margin,platform margin slope,shelf facies,and further divided the sedimentary microfacies types and reveals their basic characteristics.(3)The oolitic type and vertical distribution characteristics of platform edge and oolitic with multiple genetic characteristics has been reveals systemly.Identified true oolitic,formed oolitic,radiational oolitic,multicore oolitic,concentric oolite and other primary sedimentary oolite,and dolomitization oolitic,compaction deformation oolitic,negative recrystallization and rupture oolitic and the late transformation of ooliticby microscopic.At the same time,the oolitic with multi segment distribution characteristicsduring the first to third periods of Feixianguan Formation was revealed,the second periods of Feixianguan Formation is obviously,and reveals the characteristics of the oolitic type has a certain difference in the vertical direction.(4)Based on the seismic and drilling data,the system carried out sedimentary structure characteristics and evolution of sea level and transform platform study in Feixianguan Formation,reveal the sedimentary structure the overall platform margin obviously to the East during Feixianguan Foremation,and with early SQ1 TST transgressive retrogradational,SQ1 HST early with slow transgression,oolitic the beach began to grow,the late SQ2,rapidly regression of oolitic beach development of a large area,and fast to the sedimentary structure characteristics of East before the product.the late of second periods of Feixianguan formation,cause of the Kaijiang-Liangping shelf fill and level up was completed.The mainly evolution of the study area is limited platform-platform evaporates.Formed,sedimentary structure style at the first periods of Feixianguan Formation is transgression,the second Feixianguan Formation is regression and the third-forth periods of Feixianguan Formation is accretionary.The plane distribution characteristics of oolitic at the early-middle-late periods are different during the second period of Feixianguan Formation.Based on the sedimentary structure,the correspondence of the oolitic beach distribution has been formed,and established the deposition mode of migrationduringthe early Feixianguan formation. |
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