A Study On Heterogeneities And Development Characteristics Of Chang 4+5 And Chang 6 Reservoirs In Hujianshan Area

Hujianshan area is located in the mid-western slope of the northern slope of the Ordos Basin in the northern part of the Ordos Basin.This area develops low-porosity and low-permeability reservoirs.The pore structure is complex,the content of clay minerals is high,and the diagenesis is intense.The heterogeneity of the reservoir is severe,and the production and development of the oil field is imposing.not effectively.Therefore,it is necessary to carry out research on reservoir heterogeneity.According to previous studies by Hujianshan,the chang 4+5-chang 6 oil layer group can be divided into five small layers of chang 4+5₁,chang 4+5₂,chang 6₁,chang 6₂,and chang 6₃.Based on drilling data,mudlog data,logging data,core data,test data,and production data,the division of sedimentary microfacies and the identification of structural features were performed.Based on this,the study area was studied from the microscopic and macroscopic perspectives.Reservoir heterogeneity was studied.The study found that the chang 4+5 chang 6 reservoir in Hujianshan area has a weak tectonic structure and is located in a deltaic sedimentary system.It develops a trigonal frontal subfacies controlled by the source of northwest and northeast intersections,and the main sedimentary microfacies are underwater distributary channels.Diversion Bay etc.The heterogeneity of the reservoir is mainly controlled by the sedimentary facies and is affected by later diagenesis.The type of rock in the study area is dominated by fine feldspathic sandstone and lithic feldspathic sandstone.The sorting is moderate,the particles are generally subangular,and the roundness is poor.The types of diagenesis in the study area include compaction,pressure-solution,cementation,dissolution,and metasomatic diagenesis,which have a certain impact on the reservoir’s reservoir performance.The pore type of the reservoir is mainly intergranular and feldspar.The throat type is mainly flake throat.The combination of pore throat is mainly small pore-micro throat,fine pore-micro throat.The pore structure is characterized by the overall low expulsion pressure,high mercury saturation and mercury removal efficiency,medium sortability,and slightly rough throat distribution.From the distribution of interlayers,the intra-layer heterogeneity of the chang 4+5 oil layer group is stronger than that of the chang6 oil layer group.By analyzing the stratification coefficients,sandstone densities,and inter-layer permeability heterogeneities in the layers of the chang 4+5and chang 6 oil reservoirs,comprehensive considerations reveal that the inter-layer heterogeneities are chang 4+5₁,chang 4+5₂,chang 6₁,chang 6₂,chang 6₃.It was found that the plane heterogeneity was mainly controlled by the connectivity of sedimentary facies and sand bodies.The plane heterogeneity of the chang 4+5 and chang 6 oil layer groups was relatively strong,and the physical properties of the chang6₁ were relatively good.Body connectivity is relatively good.In order to comprehensively evaluate reservoir heterogeneity,a factor analysis method was introduced to quantitatively characterize the macroscopic heterogeneity of the reservoir.According to the comprehensive evaluation of reservoir heterogeneity,the heterogeneity of each layer is in the order of chang 4+5₁,chang 4+5₂,chang 6₃,chang 6₂ and chang 6₁respectively.Finally,the influence of reservoir heterogeneity on development characteristics is analyzed from three aspects of interlayer,layer and plane,and the internal relationship between reservoir heterogeneity and development characteristics is analyzed and studied,which has certain guiding significance for production and development.