The Study Of Geological Modelling Of Chang-8₁ Reservoir In Luo1 Area, Jiyuan Oilfield, Ordos Basin

Chang 8₁ reservoir of Luo1 area in Jiyuan oilfield of Ordos basin are characterized by low porosity and permeability,rapid change of lithology and facies, and strong heterogeneity.The later work has been restricted because it is in the early development stage,lacking of accurate reservoir evaluation and reservoir parameters. Therefore,it is very important to evaluate reservoir comprehensively and build accurate three-dimensional geological model.On the basis of comprehensive study of cores,log wells and so on,taking the high resolution sequence stratigraphic theory as a direction,the sequence framework has been established and the distribution and evolution laws of microfacies have been analyzed.Then the text studied in-layer heterogeneity,between-layer heterogeneity and plane heterogeneity of Chang 8₁ reservoir by using log interpretation parameters, evaluated reservoir comprehensively on the theory of grey correlation analysis,and predicted the favorable reservoirs.At last,under the control of sequence and sedimentary,built the geological model with the software of Petrel.Follwing achievements have been obtained in this thesis:1.Chang 8₁ reservoir can be divided into four short-cycles in ascending order (SC1,SC2,SC3 and SC4),which were corresponding to Chang 8₁^2-2,Chang8₁^2-1, Chang8₁^1-2 and Chang8₁^1-1 respectively.2.Chang 8₁ reservoir belongs to delta front deposition,which can be divided into subaqueous distributary channel,subaqueous interdistributary bay,mouth bar and subaqueous natural barrier.And subaqueous distributary channel is the major microfacies,which mainly developed in Chang 8₁^1-1 and Chang 8₁^1-23.The reservoir shows middle-strong heterogeneity,and the reservoir heterogeneity of Chang 8₁^1-1 and Chang 8₁^1-2 are stronger,because the migration of the subaqueous distributary channels are frequent,and the interbeds are more and thin. While the the interbeds of Chang 8₁^2-1 are less and thick,the reservoir heterogeneity of it is weak,and the reservoir heterogeneity of Chang 8₁^2-2 is medium.4.According to comprehensive reservoir evaluation,Chang 8₁ reservoir can be divided into three types,the first type is the best,the second type is better,and the third type is the worst.Chang 8₁^1-1 and Chang 8₁^1-2 mainly develop the first type and the second type,and high quality reservoir of Chang 8₁^1-1 are located in northwest,and those of Chang 8₁^1-2 are located in southwest.While Chang 8₁^2-1 mainly develop the second type and the third type,and Chang 8₁^2-2 mainly develop the third type.5.With the software of Petrel,using the stochastic methods of Sequence Indicator Simulation and Sequence Guass Simulation,established the geological models of Chang 8₁ reservoir,which include sedimentary facies model,sand model,porosity model,permeability model and water saturation model.The reasonable prediction results are consistent to geological knowledge,which realize the lateral prediction of reservoir.