Three-Dimensional Characterization Of The Point Bar Sand Body Architecture Of The PU-I Formation In The North Of Saertu X Area Of Daqing Oilfield

The development of northern Saertu Development Zone in Daqing Oilfield is relatively high,and it has entered the stage of high water content and low recovery.However,due to the influence of interlayers in the reservoir,a large amount of remaining oil still exists in the top of the oil layer or the lateral accretionary layer.The study of sand body sedimentary model and fine geological modeling of point bar sand body can provide theoretical basis and practice for precise and efficient potential tapping of reservoirs in extra high water content period or research and fine modeling of meandering stream sand body structure in the future.Based on the high-resolution sequence stratigraphy,this study combines geological data and logging data under the condition of dense well,and uses the verification and control contrast technology of multi-step closed regional skeleton closed section to divide and compare the deposition time unit of the study area,then demonstrates the separability of PI5+6deposition unit and establishes the fine stratigraphic correlation framework of the PI oil layer.Through extensive literature research and sedimentary background analysis in the study area,the author subdivides the target layer into four subfacies of meandering stream,braided stream,delta plain and delta front.And under the guidance of modern sedimentary characteristics and sedimentology theory,the sedimentary microfacies maps of seven time units is completed by using the logging facies difference caused by the difference of energy facies of the plane river,then establishes sedimentary evolution characteristics and space extending model of sand bodies in target area: on the plane,PI1,PI2 and PI3 belong to the contiguous single sand body combination mode,PI5,PI6 and PI7 belong to the intertwined single sand body combination mode,and PI4 belongs to the band type single sand body combination mode;vertically,with the change of accommodation,migration and swing of sand body,PI1~PI7 units gradually transition from vertical cut pile mode to horizontal cut pile mode,in which the vertical cut pile of PI1~PI3 is serious,PI4~ PI7 are dominated by misalignment cut pile and misalignment-transverse cut pile.The author further finely dissect the internal structure of the PI1 unit point bar,synthesizing the anatomy of modern sediments,outcrops and dense wells,then recognizes that the meandering stream point bar has a configuration deposition mode characterized by the gradual growth of lateral aggradation along the river steam with the enlargement of meandering stream curvature.The authors recognize that the meandering river point dam has a configurational sedimentary model characterized by the gradual growth of the meandering river along the curvature of themeandering river.Then he uses the configuration parameters of point bar sand body as constraints,edits the space surface in lateral accretionary interlayer with the external coordinate editing method,establishes a three-dimensional geological model of the meandering stream point bar,performs three-dimensional characterization of the internal configuration,heterogeneity,and of distribution of porosity and permeability of point dams,and provides important theoretical support for the fine geological study of meandering stream point bar in the future.