New idea of lithofacies modeling for tight sandstone reservoir
The types and spatial transition of lithofacies in tight sandstone reservoirs are complicated,with inter-well predic-tion being very difficult.Therefore,it is difficult to accurately characterize and make three-dimensional geological modeling with conventional modeling methods.In this study,taking well zone Dk13 of Daniudi gas field in Ordos Basin as an exam-ple,combining cores,logging,and field outcrop data,four types of lithofacies are divided,including fine conglomerate-gi-ant grained sandstones,coarse-grained sandstones,mid-fine grained sandstones and siltstones,and distribution character-istics of each lithofacies are defined.On this basis,a new lithofacies modeling idea of"zoning constraints and embedding step by step"is proposed:under the constraint of the maximum boundary of lithofacies plane distribution,facies modeling is carried out within the boundaries of fine conglomerate-giant grained sandstones facies and coarse sandstone facies respec-tively,and then each lithofacies model is embedded into the mid-fine grained sandstones facies model in turn to complete the modeling.The results show that the model is in line with the geological distribution characteristics,with high accuracy and stability.The average match rate of lithofacies in a single layer is over 90%.Compared with the conventional modeling idea,this idea does not use the completely random method in the prediction of inter-well lithofacies but uses the results of reservoir architecture analysis more,greatly improves the accuracy of inter-well lithofacies prediction,reproduces the com-plex spatial distribution pattern of lithofacies.
tight sandstonelithofaciesreservoir modelingDaniudi gas fieldreservoir architecture
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