Determination method of retrograde condensate oil saturation in sandstone condensate gas reservoirs developed by depletion

Abstract

The invention discloses a method for determining retrograde condensation oil saturability in a depletion development sandstone condensate gas reservoir reservoir. The method comprises the following steps: 1, obtaining a core of the actual reservoir, and cleaning and drying the core; 2, testing the gas phase effective permeability Kegi under different oil saturation Soi conditions, and determining the values of the parameter a and the pameter b in the formula Soi=aln (kegi) +b; 3, preparing formation fluid samples; 4, restoring the core to the original reservoir state; 5, lowering the pore pressure in the core, and recording the core inlet end pressure, the outlet end pressure and the core outlet end output air volume; 6, calculating the gas phase effective permeability Kfegi under the mean pressure condition in the core depletion process; 7, calculating the retrograde condensation oil saturability Soi in the sandstone condensate gas reservoir under different pressure conditions. The method is reliable in principle, simple and applicable, influence of porous media, water saturation and condensate oil flowing is taken into consideration comprehensively, and wide market prospect is achieved.

Description

technical field [0001] The invention relates to a method for determining the reverse condensate oil saturation in the depletion-type development of sandstone condensate gas pool reservoirs in the field of petroleum and natural gas exploration and development. Background technique [0002] Condensate gas reservoirs refer to the hydrocarbons accumulated underground under the temperature and pressure of the reservoir, the heavy components of gasoline fractions to kerosene fractions and a small amount of high molecular hydrocarbons are dispersed in the natural gas in a uniform vapor state, when the reservoir pressure is lower than When the dew point pressure is reached, heavy components (condensate oil) in the system will precipitate and exist in the pores in the form of liquid phase, reducing the flow capacity of the gas phase. Therefore, determining the reverse condensate oil saturation under different pressure conditions is of great significance for the quantitative evaluatio...

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Problems solved by technology

However, because conventional volumetric depletion experiments do not consider the effects of porous media, water saturation, and condensate flow, the determined retrograde condensate saturation is quite different from that in porous media (Wang Zhouhua. Influence of oil-type condensate gas phase state, Drilling and Production Technology, 2009, 32(3), 56-59); In addition, using ultrasonic and other modern physical testing techniques to directly test the oil saturation of porous media retrograde condensate, the experimental test is complicated and difficult (Guo Ping, Application of Ultrasonic in Testing Critical Flow Saturation of Condensate Oil, Natural Gas Industry, 2001, 21(3): 22-25)

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