The Research On Geologic Characteristic Of Yan-7 Reservoir Of Jiyuan Oilfield In Luo 226 Area,Ordos Basin

This paper takes Yan 7 layer of Yan'an Formation in L226 area of Jiyuan Oilfield in Southwestern Ordos Basin as the research object,guided by sedimentology and reservoir geology,and based on core,drilling,well logging,experimental testing,oil testing and development dynamic data,using scanning electron microscopy,high pressure mercury injection,real sandstone model visual seepage flow and other experimental methods,combines macro with micro organically,structural characteristics and distribution characteristics of sedimentary microfacies are studied on the basis of stratigraphic division and correlation,the distribution of sand body is depicted on the basis of facies-controlled,and the micro-pore structure,reservoir heterogeneity and oil-water seepage flow are studied carefully.The reservoir type is determined,the energy of edge and bottom water in reservoirs is evaluated and the productivity control and influencing factors are analyzed,to provide a solid geological foundation to study the rational,scientific and efficient development of the target area.The results show that:?1?Yan 7 layer of L226 area is a nearly EW-trending nasal uplift structure composed of several sub-nasal uplift structures with good inheritance in each layer;?2?Yan 7 layer of L226 Area is braided river delta plain subfacies deposit;Yan 7 has developed 1-2 channels,generally extending north-south,with good inheritance in each stage,hydraulic power increased slightly from Yan7₂ to Yan7₁,the distributary channel is the dominant facies zone of oil.On the basis of facies-control,the distribution of sand bodies is depicted,and the continuity of sand bodies in L226 area Yan7₁ and 7₂ is well;?3?The lithology of Yan7 reservoir is dominated by coarse-medium feldspathic quartz sandstone,with7.9%interstitial material,mainly siliceous cements and iron calcite.The pore throat structure is well-developed,the mercury removal efficiency is 24.9%,and the displacement pressure is0.042 Mpa.?4?Yan 7 reservoir has a porosity of 12%-18%,an average of 15.8%,a permeability of 50×10^-3 um ²-400×10^-33 um ²,an average of 255.8×10^-3 um²,which belongs to medium porosity-medium permeability and medium-weak heterogeneous reservoir;?5?The oil-bearing and productivity of Yan 7 reservoir in L226 area are mainly controlled by structure,and the sedimentary facies belt and physical properties of reservoir also have some influence,which is lithologic-structural reservoir;?6?Yan 7 reservoir has a certain amount of edge and bottom water,and the volume method is used to calculate the water-oil volume ratio.It is considered that the bottom water of Yan 7₁ reservoir is developed but not active.However there are also local water breakthrough affecting productivity.How to control water and stabilize oil production is the key to the next stable production of Yan 7₁ reservoir.