| Ordos basin is a multiple cyclic composite type basin, oil and gas geology resources are rich, has the very high oil and gas exploration and development value. FanXue district is located in the northern shaanxi ordos basin slope of the Midwest, is to extend the oilfield company in ordos basin in DingBian an important oil-producing areas, is also extend oilfield company so far the only YiDunJi get ready to oil region. The Jurassic Yan'an Formati is the main oil FanXue oil region one of the layer.FanXue oil region Yan'an Formati rich county Jurassic formation denudation, since the suffer in tableland's highlands, the lower reservoir Formati delay Yan'an Formati 10 is missing, only to save delay 9-4 delay formation reservoir, with the formation distribution stability. Yan'an formation total about 180 m thick～250 m, the coal development, delay, delay 7 and 9,6 top three sets of coal seam delay stable development, thickness of coal seam general 1 m～3 m, is the formation of Yan'an division and correlation of main mark layer.The research results show that the study area of 8, deferred Yan'an delay 9 reservoir structure being successive Formati, in east west in the background of the forward, development because the formation of difference of the formation of the compaction north east, south west-south to show the cloth nasal shape uplift, tectonic relatively simple. FanXue oil region of 8, deferred Yan'an Formati delay 9 sedimentary facies reservoir Formati mainly for delta plain mesh river, swamp facies, and development of distributary channel, river rooms, crevasse-splays, natural mention, lakes, swamps sedimentary microfacies, distributary channel reservoir sedimentary control the distribution of cloth and development.The study area of 8, deferred Yan'an Formati delay 9 oil reservoir development Formati, single small thickness, heterogeneity is higher. Exploratory Wells core analysis shows that, FanXue oil reservoir Formati delay 9 Yan'an Formati reservoir are mainly grain of gray, gray quartz sandstone feldspar, time for cutting feldspar sandstone, feldspar sandstone, quartz average was 74.3%, the content of 18.2% average feldspar, cutting average content 7.4%. Miscellaneous base mainly kaolinite Lord; A small chlorite, cementation content with secondary quartz primarily, cementation types to silicon cementation is given priority to, followed by calcium cementation, and a small amount of iron cementation. Lithologic dense medium degree, weathering degree medium; A particle size 50 to 200μm between, to pad type contact, sorting characteristics of medium, ground roundness medium-is poorer, main development primary pores, mix pore, fracture porosity and born secondary intercrystal pore; Delay 8 Formatis reservoir reservoir mainly by quartz, feldspar, debris composition, miscellaneous base mainly by illite, kaolinite Lord; Cementation content with magnesium calcite, iron dolomite is given priority to, followed by secondary quartz. Cementation types to calcium cementation is given priority to, followed by silicon cementation. Delay and oil reservoir lithology density degree of medium-is poorer, weathering degree is strong; A particle size 50 to 500μm between, give priority to with line contact, sorting the gender is good, good, a medium mill roundness, main development primary pores, mix pore, fracture porosity and born secondary porosity, quartz sandstone for feldspar, debris feldspar sandstone, feldspar sandstone.Yan'an Formati delay 8,9 delay Formatis reservoir main reservoir porosity distribution between 0.5%～23.72%, the average 17.9%, mainly permeability distribution in 12 x 10-3μm2-89 x 10-3μm2 between, average and x 10-3μm2, belong to the special low porosity, extra-low permeability reservoir. The typical capillary pressure curve analysis shows that, Yan'an Formati delay and oil reservoir pore structure of big hole in the larynx and holes, small and medium-sized throat primarily. Row flooding for 0.035 Mpa pressure, the median 0.175 Mpa pressure, larynx way median radius is bigger (3.55 u m), pore throat sorting is poorer, sorting coefficient is 3.6, the refund 45.45% efficient mercury, into mercury saturation is as high as 92.2%, in an average of more than 90%. Yan'an Formati delay 8 Formatis reservoir pore reservoir average 83μm, row flooding pressure is 0.027 MPa, median pressure 0.155 MPa, median radius 3.53μm, the biggest into mercury saturation 93.5%, the refund 43.15% efficient mercury, larynx way sorting coefficient 4.3, the pore structure of holes, holes in the fine throat type.FanXue oil region of 8, deferred Yan'an Formati delay 9 reservoir Formatis reservoir diagenesis type more, diagenesis relatively intense, mainly has cementation, compaction effect, account function, dissolve role as well as the pressure dissolve role, etc.Research shows that the study area of Yan'an Formati y8, deferred 9 oil reservoirs of mainly affected by the development of the reservoir sedimentary facies, reservoir porosity and permeability of the development conditions, heterogeneity and diagenesis influence. Delta plain mesh river distributary channel control the reservoirs of the exhibition cloth, development of the reservoir thickness, reservoir physical properties and pore throat structure is heterogeneity and diagenesis, the influence of porosity, permeability of reservoir determined the oil performance. Use of changqing oil field Yan'an Formati reservoir evaluation standard of the study area of Yan'an Formati y8 I Jurassic reservoir average of 5%,Ⅱreservoir average of 85.0%,Ⅲkind of reservoir average 15.0%, delay and I kind of reservoir average 15%Ⅱreservoir average of 75.0%, III kind of reservoir average 10.0%, and the overall evaluation of low permeable holes for rough throat type. |
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