Sedimentary Microfacies Characteristics And Distribution Of Pinghu Formation In Kongqueting Region,xihu Sag Of East China Sea

Kongqueting gas field is located in the nose uplift in the westen slope of Xihu sedimentary sag.There are 7 exploration well and 7 development well in the study area.All of them have industrial oil and gas flow.Great exploration potential of this area has been revealed.Pinghu formation is one of the main producing layers of the Kongqueting gas field.Hence,studying the sedimentary microfacies types of the Pinghu formation in the area,and intensive study the vertical distribution and the plane distribution characteristics of sedimentary microfacies of each sand groups of the Pinghu formation reservoir,analyzing the characteristics of the sand body plane distribution of each target sand groups are of great significants for further exploration and development of the Kongqueting gas field.During this research,firstly,according to the principles of classic sequence stratigraphy and the characteristics of target strata and lithology,I completed the sand group stratigraphic division and the small layer division of target sand group.using the latest core,logging,and all kinds of test data,analysing all kinds of phase markers of kongqueting gas field in Pinghu formation,including rock composition,size structure,mudstone color,sedimentary structure and logging curve characteristics,Judgeing the Pinghu formation of the Kongqueting gas field are developed tidal flat facies and braided river delta facies,which further divide into 4 subfacies and 10 microfacies types.The braided river delta facies is divided into braided river delta plain subfacies and braided river delta front subfacies,and then subdivided into five microfacies: braided channel,Vietnam shore deposit,underwater distributary channel,distributary channel and estuary dam.The tidal flat facies is divided into two subfacies,including the upper tidal zone and the intertidal zone,and then the five microfacies of the swamps,sand flat,mixed flat,mud flat and tidal channel are further subdivided.The response template of each phase and various phase marks was established,and the single well phase analysis was carried out for each well.According to the results of seismic attribute inversion provided by the first party and the calculation of the sandstone thickness value and sand ratio of each sand groupthe,Basing on the above sedimentary environmental correlation analysis,the distribution characteristics of microfacies in each sand group are analyzed and sand thickness and surface distribution contour map of each sand group in the Pinghu formation of the study area are drawn.