Research On The Reservoir Characteristics Of The Chang-8Member And High-yield Of The Geological Factors In Zhenjing Oilfield

Chang8formation of Zhenjing in the south of Tianhuan depression in Ordosbasin is a reservoir with large area,low abundance,low permeability, strongheterogeneity in planar and vertical scale.The enrichment of oil and gas and the levelof capacity is closely related with the distribution of effective reservoir and theformation of fracture development, etc.In-depth study of the internal factors of highproductive of oil and gas of Chang8formation,to form the regular understanding,andprovide strong geological evidence for Zhenjing oilfield to increase reserves andproduction of important guiding significance for the Chang8formation of the nextexploration and development.So far, a large number of exploration and development work has done forZhenjing oilfield of Chang8formation. On the basis of the results of previous studies,the sedimentary characteristics of the reservoir, the physical properties and fracturecharacteristics are analyzed, combined with dynamic characteristics of single well oflong8reservoir production Wells, to summarized the main factor of oil and gas highproduction from the effective thickness, physical property, fracture development ofreservoir.The study showed that: chang8formation of Zhenjing is a braided river deltafront deposits, specifically divided into5microfacies.Including subaqueousdistributary channel, subaqueous natural barrier, subsea crevass-splay, mouth-bar,subaqueous interdistributary embayment.,subaqueous distributary channel andmouth-bar always development reservoir of delta depositional system.Chang8of thereservoir rocks are mainly gray, gray-green, dark gray, middle-fine grained feldspathiclitharenite sandstone, lithic arkose sandstone,the average effective porosity of8.5%,the average effective permeability of0.3×10-3μm2, comprehensive evaluation of thereservoir to the low porosity and permeability, the fine pore throat and poor sorting.Core fracture observations indicate that the study area are mainly vertical fracture andhigh-angle oblique fracture, its occurrence is mainly concentrated in the more than70。.Fracture in conventional logging has a significantly lower resistivity and intervaltransit time and neutron increases, the density decreases, the well diameter holeexpanding; the faults and regional stress field2fracture development of the maincontrol factors has been determined,the study found that the fault of fracture densityhas details with the distance from the fault and the fault scale; on this basis,The3-dfinite element method of the town of the area chang-8strata printed branches andYanshan and Himalayan3crack formation of ancient tectonic stress field, establishedthe simulated rock damage degree and close relationship between fracture development, completing chang-8stratigraphic area of cracks in the distributionforecasting and evaluation. Results show that the reservoir structural fracturedevelopment zone and the development zone is mainly distributed in the fault zone,with core observation, logging interpretation fracture development section has goodexperimental data.Through the analysis of characteristics of single well productionperformance, well and well productivity of big differences, the productioncharacteristics obviously difference There are3types production of dynamiccharacteristics of high-yield straight well. Class Ⅰ for high-yield and stableproduction type; Class Ⅱ for the lower yield can be stable production type;class Ⅲfor production decline, and lower production can not be normal production type;dynamic characteristics of high-yield horizontal wells for2types, class Ⅰ forproduction stable water content increase slowly type, class II water content increaseand production decline fast type. Through to chang8reservoir characteristics andsingle well dynamic research, determined three main control factors of affecting thehigh-yield of the oil and gas: the reservoir of the total effective thickness, the physicalproperty of reservoir parameters and reservoir fracture development; On this basis,according to the character of sandstone exhibition, petrophysical property distributionand fracture prediction of reservoir properties favorable areas, combined withhigh-yield well distribution characteristics of the plane, and finally determined thatHH37, HH73area are two high-yield enrichment advantageous area.Through the study of the above, forming low permeability reservoir geologicalfactors of high-yield enrichment of the basic ideas and methods, deepen theunderstanding of the effect factors of the single well productivity of Zhenjing, providescientific basis for the reservoir of efficient development.