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Evaluation On Reservoir Characteristics And Distribution Of Lower Paleozoic Era In Central Tarim Basin

Posted on:2012-06-20Degree:MasterType:Thesis
Country:ChinaCandidate:G Q HouFull Text:PDF
GTID:2210330338967842Subject:Oil and gas field development geology
Abstract/Summary:PDF Full Text Request
The exploration prospect of Lower Paleozoic carbonate reservoirs in Tazhong area is quite good, but the existisng researches have shown that the types of carbonate reservoirs in this area are characterized by diversity and complication, and the reservoirs are of strong heterogeneity. In addition to the condition that the reservoir distribution rule is not quite clear, the exploration process is constrained. So, it is quite necessary to proceed further study about carbonate reservoirs in Tazhong area and objectively evaluate the reservoir quality and its spatial distribution characteristics.On the basis of previous studies and by full use of analysis data like mud logging, drilling, logging and well test data, the author has researched the reservoir physical property, pore structure characteristics and storage space, and has finished the evaluation of reservoir characteristics and spatial distribution characteristics.The core test results have shown that the Ordovician reservoirs belong to low-porosity and low-permeability rocks. The reservoir in Lianglitage Formation and Yingshan Formation develop better; porosity of samples in some layers is higher than 4%, which indicates better reservoir performance; porosity of dolomites is higher than limestone. The formation matrix permeability is quite low, but there are samples in Lianglitage Formation and Yingshan Formation have very high permeability, which indicates micro-fractures in the reservoir. The pore types in studying area are diverse, some reservoirs are with big pores and thick throats, but most the rocks belong to dense carbonate reservoirs. The researches have also shown that dolomites are the main reservoir types in studying area, and intercrystalline pore and intercrystalline dissolved pore, corroded pore and cave and cleft in karst are the most important and developed infiltration and storage space.Based on principles of BP neural network theory, the author has interpreted the porosity of 19 wells and has archived good results. On the basis of interpreted porosity, the reservoirs of every single well have been classified and evaluated. TypeⅠa nd typemⅡreservoirs mainly distribute in Lianglitage Formation, Yingshan Formation and Penglaiba Formation; the ratio of typeⅠand typeⅡreservoirs'thickness to total formation's thickness is 0.2-0.3. The reservoirs distribute laminatedly in the formation and reservoir of which thickness is higher than 10m could also be found.Lianglitage Formation reef and shoal facies is the advantageous area for reservoir distribution. Dissolved pores and dissolved caves are developed in grain limestone, because the pores and caves are small, the reservoirs belong to dissolved vug reservoir. The reservoirs mainly distribute in the upper shale strip limestone section and the middle grain limestone section. The prospect area for reef and shoal facies reservoirs of Lianglitage Formation is located in Tazhong No.1 fault belt and reservoirs of Lianglitage Formation in Katake No.1 block are not developed.Pore types of Yingshan Formation and Penglaiba Formation are mainly intercrystalline dissolved pore, dissolved pore, dissolved vug and karst fracture-cavity, but the vugs and pores are small. The reservoirs belong to dissolved vug limestone reservoir. Yingshan Formation mainly develops in the upper section. The reservoir in Yingshan Formation and Penglaiba Formation are well developed in areas where Sangtamu Formation is lost in the top of Ordivision system.
Keywords/Search Tags:Tazhong Area, Ordovician system, Reservoir Physical Property, Pore type, Reservoir Evaluation
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