The lower limits of physical properties for deep clastic reservoirs in north Songliao basin and its relationship with microscopic features

TLDR: In this paper, the lower limits of effective porosity and permeability for reservoirs where oil can be accumulated and produced are determined based on the research on lithology, physical properties, pore structure, and pore microscopic features of sandstone and conglomerate reservoirs with different productivity.

Abstract: Based on the research on lithology,physical properties, pore structure,and pore microscopic features of sandstone and conglomerate reservoirs with different productivity,the porosity permeability versus productivity charts for sandstone and conglomerate have been established with the consideration of gas testing results.According to the research,the lower limits of effective porosity and permeability for reservoirs where oil can be accumulated and produced are determined.The lower limit of porosity for sandstone is 4.1%5.5%,and that of permeability is 0.06×10-3μm2.The lower limit of porosity for conglomerate is only 2.7%,and that of permeability is 0.05×10-3μm2,because the single conglomerate layer is thick,the microfractures are vegetal and the expulsion pressure is low.Further study indicates that the difference of the main pore type,capillary pressure curve characteristics,diagenetic features and the dominant factors for reservoirs between the gas pay and dry formation results in the gas-bearing difference of reservoirs.Due to the great difference of microscopic features,such as pore type and expulsion pressure,between sandstone and conglomerate,the lower limits of physical properties vary greatly.