| Chang 3 reservoir of Weibei 2 wellblock belongs to low permeability reservoir which has large content of oil and gas resources,and the development potential is tremendous.Aiming at this kind of reservoir for elaborate reservoir description,it is the basis to potential exploration in old area and to improving recovery efficiency,it is also the key to stable work at the developed oilfield.This passage is based on sedimentology,petroleum geology,sequence stratigraphy,geophysics,geostatistics and the stochastic modeling disciplines for methods,using all aspects information such as geological,drilling,logging,well logging,testing,core analysis and dynamic production to accomplish major reservoir elaborate description and 3D geological model of reservoir research in Weibei 2 wellblock.On the basis of predecessors' research results,with the actual formation lithology,electrical combination feature as the starting point,and on the basis of the original segment small layers standard,and dividing chang 331 layer into three segment layer which is chang331-1,chang331-2,chang331-3,dividing chang 332 layer into 2 segment layers which is chang332-1and chang332-2,dividing chang 333 layer into 2 segment layers which is chang333-1and chang333-2,study shows that microfacies of chang3 of weibei oilfield mainly has delta front underwater distributary channel,distributary bay,river mouth bars,channel flank,etc.they are made up of delta front subfacies.presenting for advancing lake basin delta sedimentary system,which is mainly underwater distributary channel microfacies.The reservoir in the study area with fine grained,is mainly very fine grain of lithic arkose,carbonate content is relatively small.With a high content of feldspar and lithic sandstone,quartz is relatively less,and has low composition maturity characteristics.Thus it determines its own permeability structure,reservoir with low porosity,low permeability,and high reservoir heterogeneity.Each layer porosity contour map and the statistical porosity analysis results show that the porosity of chang33 reservior concentrates on 9%~15%,and the average porosity is 12.37%,Statistical results of each layer analysis show that the reservoir of chang 33 permeability value range is larger,ranging from 0.045×10-3?m2 to 7.69×10-3?m2,and the average is about 0.886×10-3?m2,the permeability value concentrate on 0.3×10-3?m2~2×10-3?m2,most of them are less than 1.0×10-3?m2.Internal reservoir has no apparent oil-water separation phenomenon,and there is no boundless or bottom water,Saturation pressure is lower than the original formation pressure,and the pressure coefficient is smaller(<0.75),So it is Comprehensively determine reservoir is unsaturated abnormal and low pressure lithologic reservoir.reservoir original drive way is mainly the elastic drive,the other driver is complementary.Regarding the single sand layer segment as a unit,combined with the comprehensive evaluation results,calculate reserves after reservoir classification.Total reserves is 704×104t in the study area,of which type I reserves accounted for 29%,class II reserves accounted for 43.5%,class III reserves 27.5%,the difficulty development reserves producing exists difference.Lastly,on the basis of the comprehensive geological research.with the petrel software,on the basis of comprehensive geologic study of 3D geological model is set up,the image intuitively show how porosity and permeability of formation distribute,to estimate geological reserves.Research district estimate the geological reserves of chang 33 is 699.78 x 104 t,chang33 reservoir geological modeling and working area covers an area of 12.3 km2,the abundance is 56.89 x 104 t/km2.Results are compared with common geological reserves calculating method,error is less than 1%,the model set up successfully.This model makes a solid foundation for the further numerical simulation of reservoir engineering design. |
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