Study On Reservoir Geological Characteristics In Liugou Area Of Wuqi Oilfield

In this paper,the Liugou area of Wuqi Oilfield in the Ordos Basin is the main research block.The main oil-producing layers are Yan9,Yan10 and Chang2 in Yanan Formation.In this study,the Yanan Formation Yan9 and Yan10 reservoirs are As the research object,through multidisciplinary research methods such as sedimentary petrology,sequence science,and oil and gas accumulation geology,combined with a series of data such as cores,scanning electron microscopy,logging,drilling,logging,and oil testing and production testing,qualitative and quantitative The formation thickness,structural characteristics,sedimentary characteristics,reservoir characteristics and oil reservoir characteristics in the study area are studied in order to find the most favorable sublayers for oil production.Firstly,the strata in the study area are divided into five sub-layers,namely Yan 9¹,Yan 9²,Yan 10^1-1,Yan 10^1-2and Yan 10²by means of marker layer and deposition cycle control.Structural characteristics research,it is found that it is consistent with the regional geological structure,it is a gentle monoclinic dipping westward,with good inheritance;secondly,on the basis of the division of small layers and structural characteristics,macroscopic observation of outcrops and microscopic observation of rock thin sections are used.method,carry out research on sedimentary characteristics,and discuss the spatial distribution law and characteristics of sand bodies under the constraints of sedimentary facies belt;use mercury intrusion method to study pore types and pore-throat structure,and analyze reservoir non-linearity through reservoir parameters.Homogeneity and sensitivity;finally,use fluid properties,reservoir profile and plane characteristics,and oil-water distribution laws to study reservoir characteristics,and use volumetric method to calculate reservoir reserves,for efficient development and rationalization of target intervals in the study area.The arrangement of injection-production well pattern and enhanced oil recovery provides a solid geological foundation.The research shows that:（1）the thickness of the Yan 9 formation in the Jurassic Yan’an Formation in the study area is 40-60 m,the thickness of the Yan 101 formation is 15-30 m,and the thickness of the Yan 102 formation is 20-40 m;（2）Sedimentary microfacies such as side beaches and river floodplains are developed;（3）The rock types of Yan 9 reservoir are mainly lithic sandstone,feldspar lithic sandstone,and lithic quartz sandstone;the interstitial species are mainly kaolinite,hydromica,iron minerals And anhydrite,followed by calcite,dolomite,siliceous,etc.The sandstone is mainly distributary channel sand with fine particle size.The Yan 10 sandstone is mainly composed of light gray,gray-white fine-medium-grained feldspar quartz sandstone,and the interstitial materials are mainly composed of kaolinite,hydromica,iron dolomite and siliceous.Mainly sub-circular,well sorted and medium,the cementation type is mainly enlarged-porous type,with a small amount of pore type;（4）Yan 10 oil layer group is a set of mesoporous-medium permeability reservoirs with strong heterogeneity;（5）The Yan 10 reservoir is weakly water-sensitive,no velocity-sensitive,weakly acid-sensitive,and moderately highly alkaline-sensitive;（6）The Yan 10 crude oil in this area has low specific gravity,low viscosity,low asphaltene,low freezing point,and initial boiling point.Low,high wax content,sulfur-free characteristics;（7）The distribution of oil and gas in the Yan9 and Yan 10 layers of the Jurassic Yan’an Formation in the study area is mainly controlled by paleochannels and paleogeomorphology,and is restricted by the dual factors of lithology and structure,mainly forming structural-lithologic traps;（8）Using the volume method to calculate the proven geological reserves of Yan 9 and Yan 10 layers,the total reserves are 1560.7×10⁴t,which has great development value.After the above research,it is concluded that the most favorable sublayers in the Yan’an Formation in the study area are:Yan 9¹,Yan 10^1-2,and Yan10².