| Tarim Basin is the largest petroleum basin in China,its Ordovician carbonate rocks have made significant breakthrough in oil and gas exploration.As an important strata of exploration in Basin,Yingshan Formation has great exploration potential.The thesis takes the Shuntuoguole lower uplift as the research area,and the Yingshan Formation of Ordovician as the research object,used field geological data,drilling core data,seismic and logging data,guided by multidisciplinary theory,the characteristics of rock microfacies,sedimentary facies and sedimentary evolution of Yingshan Formation in the study area has been studied.The results provide basic data for further exploration in Yingshan Formation.The Yingshan Formation of Ordovician in Shuntuoguole lower uplift is a set of carbonate deposition,and the strata is stable.According to logging,core data and the characteristics of the lithology,the Yingshan Formation can be divided into two sections,upper Yingshan Formation and lower Yingshan Formation.The upper Yingshan Formation is dominated by micrite limestone and granular limestone,while the lower Yingshan Formation is mainly deposits dolomitic limestone,dolomite,silty-fine dolomite and micrite limestone.Through the systematic study of the petrology characteristics of the Yingshan Formation.There were three major types of rock are identified in the study area,which is limestone,dolomite and transitional rocks.Based on the structural characteristics,nine major rock microfacies types are further classified(MF1-MF9).Besides,established four main rock microfacies sequences,including thin-layer low-energy beach microfacies sequence(MA1),thin-layer middle-energy beach microfacies sequence(MA2),high-energy sand Beach microfacies sequence(MA3),high-energy algal beach microfacies sequence(MA4).The sedimentary facies types and characteristics of the Ordovician Yingshan Formation in the Shuntogol lower uplift are defined,divided into three sedimentary facies,which is restricted platform,open platform and platform margin,and five subfacies and eleven sedimentary microfacies types.Seismic facies characteristics have been studied,and there are ten kinds of seismic reflection characteristics in the study area,such as medium amplitude,medium continuity,low frequency,medium-strong amplitude,medium-difference continuity and medium-low frequency.Through the interpretation of these seismic facies,the transformation between seismic facies and sedimentary facies was realized,which provides a basis for the subsequent compilation of sedimentary facies.Based on the analysis of the plane distribution characteristics and evolution of sedimentary facies of Yingshan Formation in the study area,it is considered that the Yingshan Formation has developed restricted platform facies,open platform facies and platform margin facies from west to east,and narrow ring-like platform margin slope facies and basin facies was developed in the periphery of platform margin facies.In the early stage of Yingshan Formation,developed restricted facies,platform shoal and limited platform subfacies.The size of granular shoal was small,and the sedimentary thickness was not large,mainly deposited fine-grained dolomite with a small amount of limestone.With the gradual rise of the sea level,the sedimentary environment of the late Yingshan Formation began to change to an open platform,due to frequent fluctuation of water,many sets of sedimentary cycles of intra-platform and interbank sea subfacies were developed.Vertically,the beach was superimposed,and was generally isolated and discontinuous in the plane,mainly composed of medium-low energy sandy beach,and the lithology was grainstone,sparite limestone and micritic limestone. |
PDF Full Text Request