Sedimentary Facies Feature Research On Z Reservoir Of Block N Of Tamtsag Oilfield In Mongolia

Z reservoir of Block N of Tamtsag oilfield in Mongolia is a duplex fault structure with faulting in the east and overlying in the west, which is characterized by widespread strata erosion and loss, unconspicuous mark layers, multiple provenances, frequently changed facies and multiple overlapped fan. Because stratigraphic correlation and sedimentary microfacies research are difficult, and research area has not yet carried out a unified fine reservoir description work, it is necessary to study of stratigraphic division, stratigraphic framework, sedimentary facies types and their distribution characteristics.This paper through the establishment of the "four level" mark layer system in research area, unifying the stratified boundaries of each fault block, establishing a unified stratigraphic framework. On the basis of previous research achievements, we study on sedimentary characteristics and establish sedimentary model for the first time. Using the "three steps"drawing process, we draw 14 Sedimentary microfacies charts and conclude about the characteristics of sedimentary distribution.This research results showed that the research area belongs to neritic subaqueous fan deposition model, including 3 subphases, 5 microphases, and identified separately lithology and electrical characteristics of each microphases. Sedimentary distribution characteristics is summarized as double-source supplied from east and west, large area of lacustrine facies in the middle part, and turbidite scattered across the lacustrine facies. Summed up the regional sedimentary distribution characteristics, advantages of main channel and characteristics of braided waterway development, and the control of dominant reservoirs.