Evaluation On Characteristics Of Deltaic Front Sand Bodies Of Gao-Tai-Zi Reservoir In Changling Depression, Southen Songliao Basin

This thesis is mainly aimed at the evaluations of Deltaic front SandBodies of Gao-Tai-Zi reservoir in Changlin Deperssion, Southern SongliaoBasin. The aim of this paper is providing scientific foundation ofexploration and development for low-permeability reservoirs in this area,and perfectly setting up synthetically quantitative evaluation methodsaiming at low-permeability sand reservoirs, and enriching and developingcontinental reservoir sedimentary theory in Chinese characteristics.On the basis of sedimentary microfacies study, the author discussesthe properties of genetic units in the line with reservoir heterogeneityanalysis and with the emphasis on microscopic structures of reservoir pores.The research work is carried out from macro-scale to micro-scale and fromqualitative to quantitative analysis based on large number of laboratorymeasurements and previous studies. The reservoir features of Gao-Tai-Zireservoir and others are integrated studied in Changli Depression and itssurrounding areas in Southern Songliao Basin and mostly addressed in thefollowing seven aspects: (1) Relations between reservoir heterogeneity anddistribution pattern of oil and water;(2) Analysis od reservoirconstituents and their controlling factors including reservoir petrology,distribution and conversion of clay minerals, diagenesis and its effectson reservoir petrophysics, etc.;(3) Description of pore structures andits application;(4) Detailed dissection analysis on reservoir rocks withthe application of a special test of mercury injection pumping with constantrate;(5) Reservoir analyses of microscopic heterogeneity and permeableproperties;(6) Appraisals of reservoir sensitivities and furtherprotection proposal for reservoir;and (7) Systematic evaluation andsorting on reservoirs. The main innovational production of the paper isas follows:(1)Quantitative analysis of the distribution and conversion of clayminerals with the combination of Scanning Electronic Microscopy and EnergySpectrum analysis. Test results show that the vertical distribution patternof clay minerals in this area is the abnormal conversion type (II type),which could be correlated with the II-a type of vertical distribution ofclay minerals in Chinese oil-bearing basins. This pattern is controlledby the unconformity between the late Cretaceous and Tertiary. This studyprovides the quantitative fundamentals on reservoir protection in theproduction processes. The paper analyzes this kind of transformcharacteristics ,and the source matter and ancient sedimentary environmentare the most controlling factors, and diagenesis is only differentalteration to original sediments(2)Quantitative description on distributions and correlations ofreservoir pores and throats with the application of an innovativetechnology of mercury injection with constant pumping rate. This workconstructs the functions between the throat radius and permeability, andfurthermore discovers the microscopic properties of pore throat whichaffect permeability directly.(3)Firstly establishing a series of models for different layersincluding the model among porosity, permeability and mineral assemblage,and the model among different structure parameters of reservoir. It is notedthat the secondary porosity is controlled by the dissolution of unstableconstituents, and the content of potassium is one of the importantcontrolling factor of reservoir porosity.(4)There is an obvious positive correlation between the median ofcapillary radius and oil bearing (saturation) in Daqingzi area. Reservoirproperty gets more favorable with the increasing of R50, and verse versa.(5)The prediction model of production is constructed from the solutionheight (Hcwwo) under the condition of boundary water. The calculation formulaof Hcwwofrom porosity and permeability is given, and it can be applied topredict the features and potential of productions with the use of a largenumber of porosity and permeability values from log interpretation.On the basis of the systematic description and evaluation of variousproperties, the forming rules of reservoir are concluded and the nextrationalization work proposals are supplied combined with productionpractice, and accepted by Jilin oilfields.