Study On Up-scaling Technique Of Reservoir Modeling Base On The Reservoir Characteristics

Different coarsening parameters can be determined based on the statistical characteristics of the reservoir.In this way,original geological features of the reservoir are reserved and reflected as much as possible when the model grid is coarsened.It is an efficient model coarsening method that can reflect the geologic features of the reservoir.Reservoir model's coarsening technique had been well studied in current research.Coarsening mathematical algorithms were constantly improved.However,the division of coarsening mesh was mainly conducted from the mathematical perspective and different sedimentary units were inclined to adopt the unified coarsening mesh,ignoring the disparity in reservoir's geologic features.During the study,on the basis of analyzing the reservoir characteristics of target reservoir in the studied area,the research on the upscale parameter of the fine model grid is carried out.According to the actual geological condition,a model grid upscale method that can immediately reflect the actual seismic feature of the reservoir,minimize the number of grids and improve the efficiency of simulation calculation is to be established.Coarsening parameters of each sublayer in the study area are determined under the guidance of the method.Also,the fine model is refined to evaluate the relationship between the coarsening precision and the computing efficiency.Xing X pure oil zone is located in the southern Xingshugang anticline of Daqing placanticline,in the central sag area of Songliao Basin,and it belongs to the large river-delta sedimentary system.Parameter distribution rules of each sedimentary unit's reservoir thickness,property and structure,reservoir position,reservoir spacing,intercalation thickness and water washing thickness ratio are analyzed respectively to comprehensively grasp the characteristics of reservoir distribution.The study area is divided into five types of reservoirs combined with types of reservoir and corresponding LOG.Meanwhile,a coarsening experimental study is conducted on the curve characteristic parameters of the reservoir.The results show that the form of LOGs is a complex reservoir that is thick,in general,with a water washing thickness reaching around 90%.When the sampling interval is 1/4 of the thickness of the reservoir,the basic characteristics of reservoir physical property change can be reflected.LOG features thin reservoirs with finger-forms below 0.8m.A grid can be used for characterizing internal physical properties due to slight differences.And LOG features a funnel-shaped and bell-shaped reservoir with a thickness above 0.8m,in general.At least 1/2 thickness of the reservoir thickness will be needed as the vertical grid parameter when a reservoir model is established.When 1/5 of the reservoir thickness is selected as a vertical grid parameter,the boundary of differences in physical properties can be accurately described.LOG features a reservoir combining bell-shaped and funnel-shaped.Thus,at least 1/2 thickness of the reservoir thickness will be needed as the vertical grid parameter when the model is established.Moreover,when 1/5 thickness of the reservoir thickness is selected as a vertical grid parameter,the boundary of differences in physical properties can be accurately described.When LOG features a bell-box type reservoir with slight differences in internal physical properties,1/2 thickness of the thickness of the reservoir will be needed as the vertical grid parameter.Nevertheless,if precise description of boundary points of the reservoir,the sampling interval should not be greater than 1m under the constraint of 1/2 thickness.Guided by the above experimental conclusions,three sets of grid parameter classification schemes,i.e.,three-level parameter division schemes including “precise parameters”,“moderate parameters” and “efficient parameters” that are suitable for different research objectives have been established on the basis of the principle of distinguishing the reservoir thickness and reflecting the internal physical properties of the reservoir according to actual conditions.Specific coarsening parameters of each deposition unit in the study area under the three different schemes have been determined according to the differences in the reservoir characteristics of the 72 sedimentary units in the target layer of the study area.