The Study On Characteristics Of Chang 6 Reservoir And Favorable Area Prediction In Shijiapan Area In Ordos Basin

This paper takes the Chang 6 petroleum reservoir in the Shijiapan area as the target reservoir group,based on logging,core and other data,combined with dynamic data such as oil testing and production,and adopts the guidance of sedimentology and reservoir geology,using a variety of experimental analysis test methods to study the stratigraphic division and contrast,structure,sedimentary facies and reservoir characteristics of Chang 6 reservoir group in this area.Based on the above content,studied the reservoir characteristics,and with thepetroleum accumulation regulation and the development status to predict the favorable area.According to the regional marking layer,the lithological rhythm and the distribution of sedimentary cycles,the Chang 6 reservoir group of the study area is divided into Chang 6₁,Chang 6₂,Chang 6₃ and Chang 6₄,further subdivided into Chang 6₁¹,Chang 6₁²,Chang 6₁³,Chang.6₂¹,Chang 6₂²,Chang 6₂³,Chang 6₃¹,Chang 6₃²,Chang 6₄.On the basis of fine stratigraphic contrast,studied the top surface structural features of each small layer.The structural feature of research area is a gentle westward and monoclinic structure.The Chang 6oil layer group in the Shijiapan area is delta facies deposits,belonging to the delta plain subfacies,the microfacies include diversion channels and their flank,diversion intertwined land,natural dikes and crevasse fans.The main channel in the area is distributed from northeast to southwest,and the diversion channel and flank are the most favorable sedimentary facies.The Chang 6 reservoir sandstone types are mainly fine particles,followed by medium-fine feldspar sandstone and lithic feldspar sandstone.The study of reservoir diagenesis shows that the diagenetic evolution of the Chang 6 reservoir had reached the stage A of the middle diagenetic stage.The reservoir has poor physical properties and belongs to extra-low pore,ultra-low pore and ultra-low permeability reservoirs.The pore type is dominated by intergranular pores,followed by dissolution pores.The pore structure mainly includes small pores-fine throat type,small pore type-fine throat type and fine pore type-micro throat type.The interlayer heterogeneity of the reservoir is strong,and the in-layer heterogeneity of each of the Chang 6₂ layers is much stronger than that of the Chang 6₁ layers.The reservoir type in the research area is mainly lithologic reservoirs.The accumulation of Chang 6 reservoirs is mainly controlled by sedimentary microfacies and sand body characteristics,reservoir physical properties and oil content.The oil and gas is mainly distributed in the area where the main body of the distributary channel is thick and the thickness of the oil layer is large and relatively high-porosity and high-permeability.According to these characteristics,combined with the actual production situation of the research area,the favorable areas of Chang 6₁ and Chang 6₂ were screened,predicted 13favorable areas of Class I,24 favorable areas of Class II,and 6 favorable areas of Class III.Therefore,it can provide some guidance for the subsequent exploration and development of the research area.