The Subarea And Cause Of Reservoir Sandstore Based On Delta Front In Yanchang Formation Trias Of YanChi—Jiyuan Area,Odors Basin

Low-angle slope delta front is a most important reservoir position in depression lacus sedimentary system. So it is always a hotspot in research work about delta. In this paper, Yanchang Formation of Upper Triassic in the Yanchi-Jiyuan area of the basin is select, analyse the types of microfacies, the subarea of delta front and cause of reservoir sandstore, through the research above, we can draw the conclusions:Chang6-Chang2 oil-group in Yanchang Formation of Upper Triassic in Odors basin begin to shrink. Northeast is low-angle slope, develop constructive potamic-lake delta. Through the synthetical analyse about artesian well and log datum, we strike up the log response pattern and compartmentalize delta into three types of subfacies and the types of microficies. At same time, we establish the differentiate symbol and suit sedimentary pattern based on sandstone evolvement distributing in different period.The understand about low-angle slope delta front has great evolve. Based on the identity of three circumscription and two zone, The delta front in this area can be divide into " mesa delta front" and " sloping delta front" . The deposition models of delta along gentle slop is proposed based on the strength of the current in distributary channel and the depth of water in the lake. Based on research of underwater distributary channel, recombination bars and mouse bar , we can set up assorted scheme and discriminating characteristic . For example, "mesa delta front" microfacies are composed of truncated underwater distributary channels and downside remains recombination bars; and " sloping delta front" microfacies are composed of underwater superposition channels, upside remains recombination bars, integral recombination bars and river mouse bars.In Yanchang Formation Trias of YanChi-Jiyuan Area, develop three types and six subtypes reservoir sandstore. These types be c controlled by water deepness and fluvial energy.On the basis of analysis of different kinds of reservoir petrologic feature, porosity, rate of percolation, we can conclude that the reservoir physical characterization in most cases controlled by depositional facies. There are different reservoir's physical characterization in differentsedimentary location. The reservoir physical characterization in sloping delta front excelled that of mesa delta front.