| The research areais located tectonicallyin the middle Shanbei Slope of Ordos Basin and the major oil reservoirs are Chang4+5 and Chang6.The Chang4+5 reservoir in the late development of oilfield has many problems, including the declining production of oil and gas, the injection of water, the protruding injection and production contradiction. Therefore, the key of solving the problem in the development of oilfield lies in reservoir fine description at Change4+5 and building three-dimensional geological model.According to the study result of research of others, combing the regional geologic structural and sedimentary evolution characteristics at the study region, pulling together the cores, well logs, production, testing data, the paper has a fine stratigraphic division and correlation, well logging data re-evaluation, sedimentary facies research, study of reservoir characteristics at the objective layer Chang4+5 under the guidance of reservoir geology, reservoir geophysics, reservoir sedimentology and other geological scientific research methods of multidisciplinary, and use Petrel software to construct a true reflection of the subsurface three-dimensional geological model The main achievements obtained in the following results:(1) Chang4+5 strata is divided two layers (Chang4+5~1? Chang4+5~2) from the top to the bottom and stratigraphic correlation characteristic is obvious,each layer top surface structure overall is featured as the altitude of the east area higher than the west, the formation of local has small nose shaped uplift.(2)According to the well logging data,core analysis and testing data, the Chang4+5 reservoir porosity, permeability, saturation, shale content model have been established. And the lowest limit values of the reservoir physical propertyhave been determined,where the porosity lower limit value is 8 percent, the lower limit value of permeability is 0.3mD. The well logging data has been re-evaluation,evaluation results compared with the results of physical analysis, the error is very small, showing that the result is satisfying.(3)Identification and division of sedimentary results shows that:Chang4+5 reservoir sedimentary system mainly belongs to the delta plain and develop mainly the micro facies including distributary channel and distributary bay.(4)Chang4+5 reservoir lithology is featured mainly fieldspar sandstone,the average porosity is 10.32 percent, the average permeability is 0.36mD.The pore throat is typical for low porosity with narrow throat and low porosity with micro throat, the reservoir has rather higher heterogeneity.(5)Chang4+5 reservoir three dimensional geological model show that:the Chang4+5 formation thickness of each layer is relatively uniform, the structure inherited the regional structure features, feathered as the altitude of the east area higher than the west, some local areas have small ups and downs of nose uplift;Chang 4+5~2 reservoir sandstone facies model develop better than Chang4+5~1,but the standstone scatterdistribution, and mainly cocentrate in the local area of Northeasternarea of the study area and the West; reservoir attribute modelsare in the high coincidence with lithofacies models, reservoir attribute model could reflect the change of reservoir lithology, reflecting the heterogeneity of the reservoir.(6) The builtthree dimensional geological models have been inspected and evaluated.The results show that simulation model of porosity, permeability values and the physical parameter valueswhich have been calculated according to the physical interpretation model have a small difference, and the matching degree between attribute modesl controlled by reservoir facies and facies model is higher, the three-dimensional geological model is more reasonable and credible. |
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