Reservoir Heterogeneity Of Upper Es₄ Formation In The Wang 146 Area Of Wang Jiagang Oilfield

Reservoir heterogeneity is the core issue of reservoir description, which has a significant control upon the distribution of oil and gas and waterflooding. Reservoir of upper Es4 formation in the Wang 146 area of Wang Jiagang Oilfield is mainly developed in Beach-bar facies.The reservoir is characterized by thin sand bodies,low permeability and serious heterogeneity. This leads to complex development of the reservoir. To increase the efficiency of rolling exploration and development,this paper conducted research onreservoir heterogeneity of Beach-bar reservoir. The inner layer heterogeneity, interlayer heterogeneity and areal heterogeneity are described and characterized in details. On the basis of reservoir heterogeneity,this paper discussed comprehensive reservoir evaluation. Predicting the area of favorable reservoir and providing some basis for oilfield development plan.Firstly,the sequence stratigraphic framework of the study area is established and the reservoir is divided into 8 sand groups, 29 members and 64 single sand bodys according to the Principle:“cycle correlation and classification control”. Then with the combination of the structure shapes and sedimentary facies data this paper conducted research on the geostatistical inversion algorithm,predicted sand body and physical property distribution of reservoiris established.On the basis of the results of the geostatistical inversion algorithm,the inner layer heterogeneity, interlayer heterogeneity and areal heterogeneity are described and characterized by sand bodies and physical property distribution of reservoir, characteristics of barrier and interbeds and permeability heterogeneity parameters. After that,control of reservoir heterogeneity on layer scale and the distribution of oil and gas is analyzed. The study found that the lateral reservoir heterogeneity is controlled by sedimentary facies and degree of connectivity of sand bodies. The formation and distribution of beach-bar sand-body are controlled by sedimentation cycles,by palaeogeomorphology in in vertical extent. It concluded 3 modes of reservoir permeability heterogeneity and the differences of reservoir physical property and the thickness of sand bodies, which are caused by different sedimentary environment, arethe main reason for the difference of distribution of oil and gas.On the basis of the results of reservoir heterogeneity, the paper indicates porosity、permeability、permeability variation coefficient、effective thickness、net/gross ratio、density of the interlayers and shale content for a total of 7 parameters to appraising reservoir comprehensively of the CX3 sandstone units.According to REI,the paper divides the reservoir into 4 types. The Ⅱclass reservoir is theprincipal producing formation of the researched region. Then combined with the data of the structure shapes and formation, the paper predicted the area of favorable reservoir. The Ⅰ classreservoir and the Ⅱclassreservoir,which had excellent trap conditions,are profitable reservoirs. According to this, the paper predicted 3 areas of favorable reservoir.