TANG Yong, CHEN Kun, HU Xiaohu, et al. Phase behavior and development characteristics of shale condensate gas in confined space[J]. Petroleum Reservoir Evaluation and Development, 2024, 14(3): 343-351. DOI: 10.13809/j.cnki.cn32-1825/te.2024.03.004.
The exploration of Well-Fuye-10 in the Dongyuemiao section has provided valuable characteristic parameters of typical continental shale
revealing a reservoir with well-developed mesopores and macropores and significant heterogeneity. The predominant pore sizes are around 10 nm. Notably
deviations in the critical parameters of the confined fluids alter the condensate gas properties within these nanopores
differentiating them from conventional laboratory results. This study combines indoor phase state experiments
critical parameter migration calculations
and numerical simulations of confined fluids to analyze the phase state characteristics and extraction properties of shale condensate gas. The findings elucidate the phase state transformation and extraction dynamics of the condensate gas. Adjustments in the calculations for condensate gas phase characteristics to account for critical parameter offsets indicate that as pore radius decreases
there is a corresponding reduction in critical temperature and pressure of the system components. This results in a contraction of the phase diagram towards the lower left
a decrease in dew point pressure
reduced gas phase viscosity
an increase in deviation factor
and a gradual decrease in retrograde condensate saturation. Additionally
a mechanism model was employed to assess the impact of critical parameter shifts on depletion extraction effectiveness. Results demonstrate that while the recovery rate of natural gas remains relatively unchanged
the recovery rate of condensate oil shows a significant increase
rising by 9.93% as the pore radius decreases to 10 nm. These insights offer pivotal guidance for the development of shale condensate gas reservoirs
particularly in managing the unique phase behavior and optimizing recovery strategies.