Characteristics of Paleogene lacustrine carbonate reservoirs and oil-bearing property analysis:A case study of the Yingxi area of western Qaidam basin
HUANG Chenggang
WANG Jiangong
WU Lirong
NI Xianglong
YANG Sen
WU Liangyu
Abstract：To study the reservoir space types and oil-bearing properties of tight lacustrine carbonate rocks of Paleogene E32 reservoirs in Yingxi area,systemic analysis on petrology and mineralogy,physical property and capillary pressure curve,ultra-micro crystal morphology,micro-area geochemical composition and so on were carried out.The results show that the pore types of the E32 reservoirs are mainly intercrystalline pores of dolomite and these pores are full of oil.A small amount of dissolution phenomenon of organic acids indicates the potential of large-scale oil and gas reservoirs.Under the microscope and scanning electron microscope,many intercrystalline pores are found developed in dolomite rocks,and the capillary pressure curve presents a "high-wide" platform with the symbolic meaning of "small bore and large quantity".The results of electron probe show that the molecular formula of dolomite is Ca (Mg0.96Fe0.04)(CO3)2.13.36％ plane porosity can be formed in ideal conditions.Statistical data show that the intercrystalline pores are enlarged by organic acids in a few samples,and there is no evidence neither for leaching dissolution of atmospheric water nor erosion of detrial feldspar.The measured value and the value deduced by the chemical theory shows that the pore diameters are about 0.40-1.07 μm,fully capable of not only storing oil,gas and its symbiosis substance,but also allowing them to flow or migrate within.
Keywords：intercrystalline pores of dolomitestorage capacitydissolutionLacustrine carbonate rocksPaleogeneYingxi areaQaidam basin
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：14( 1102-1115 )