Multiple-point Geostatistics Modeling Of Upper Cretaceous U Sandstone Member In Mariann Oilfield,Oriente Basin

The Oriente Basin in Ecuador is the most oil-gas enriched area in the Andean foreland basin group in South America.Mariann oilfield is located in the northeast of Tarapoa block and has entered the stage of high water cut development.Every reservoir in Mariann oilfield has the characteristics of tidal controlled deposition,and the spatial distribution of the reservoir is complex.The fine characterization of the lithologic boundary and internal interlayer of the reservoir has always been a difficult problem in this area.In this paper,the Upper Cretaceous U sandstone member of Mariann oilfield is taken as an example,and the multiple-point geostatistical simulation method is used to carry out the research.Firstly,according to the logging and lithologic data,combined with 3D seismic data and paleontological data,the stratigraphic framework is divided into six third-order sequences,in which the Napo formation is divided into five third-order sequences KSQ2~KSQ6.According to the sedimentary facies indicators and the regional sedimentary evolution background of Oriente Basin,it is considered that the U member of the study area belongs to tidal sedimentary system,and the Lower U member belongs to tidal controlled estuary facies,with tidal bar,tidal channel,middle tidal flat,high tidal flat and other microfacies.The Upper U member is an inland shelf facies affected by tides,which mainly develops tidal sand ridges,tidal sand sheets,shelf mud,shelf sand mud interbedding and other microfacies.Then,based on the analysis of single well facies and cross-section facies,the plane distribution characteristics of sedimentary microfacies in the study area are analyzed,and the plane and cross-section facies models are summarized.Secondly,Google Earth software system is used to obtain a large number of measurement data and statistical analysis results of tidal sand bar and shelf tidal sand ridge in modern tidal control estuary.Combined with core,well logging,sedimentary microfacies plane distribution characteristics,well connection profile and seismic data in the study area,the geological knowledge base and Upper U tidal sand bar of tidal control estuary in Lower U section of the study area are established Geological knowledge base of tidal sand ridges in U section.Finally,according to the development characteristics of sedimentary microfacies obtained from the geological knowledge base,the training images of tidal sand bar and shelf tidal sand ridge in tidal controlled estuary were produced by using the target simulation method.Using multiple-point geostatistics method,according to the actual geological conditions of the study area,the three-dimensional geological models of sedimentary microfacies and sandbodies of Lower U and Upper U sections in the study area are established under the constraints of training images.So as to more accurately characterize the spatial geological structure of the reservoir,and provide geological basis for the next adjustment of the work area.