Quantitative study on multi-factor production capacity chart for ultra-high temperature, high pressure, and low permeability gas reservoirs
Production capacity evaluation is a critical task during the early development stages of gas reservoirs. Clarifying the impact of reservoir petrophysical properties, water saturation, and CO2 volume fraction in fluid composition on gas well production capacity is of great significance for accurately...
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| Format: | Article |
| Language: | Chinese |
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Editorial Department of Petroleum Reservoir Evaluation and Development
2025-08-01
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| Series: | Youqicang pingjia yu kaifa |
| Subjects: | |
| Online Access: | https://red.magtech.org.cn/fileup/2095-1426/PDF/1752896040736-128298450.pdf |
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| Summary: | Production capacity evaluation is a critical task during the early development stages of gas reservoirs. Clarifying the impact of reservoir petrophysical properties, water saturation, and CO2 volume fraction in fluid composition on gas well production capacity is of great significance for accurately evaluating the production capacity of low-permeability gas reservoirs. This study focused on typical ultra-high temperature, high pressure, and low-permeability gas reservoirs in the Yinggehai Basin. Using the gas-water steady-state flow experiments, the influence of water saturation and CO2 volume fraction on gas-phase permeability of cores with varying petrophysical characteristics was clarified. Based on the principle of flow velocity approximation, a quantitative multi-factor production capacity chart was established. The results showed that: (1) As water saturation in the rock increased, gas-phase permeability decreased. When water saturation in the target reservoir cores was below the irreducible water saturation (40%), every 10% increase in water saturation corresponded to an average production capacity loss of approximately 12%. When movable water existed, two-phase gas-water flow led to a sharp decline in gas-phase permeability. Specifically, as water saturation rose from 40% to 50%, gas production capacity decreased by about 70%. (2) In ultra-high temperature and high-pressure formations, the presence of CO2 in the gas composition significantly reduced the gas well production capacity. When the CO2 content was 28%, the production capacity loss rate was about 12%. As the CO2 volume fraction increased, its impact on production capacity gradually intensified. When the CO2 volume fraction reached 70%, the production capacity loss rate was around 60%. A multi-factor production capacity evaluation chart was established, incorporating the reservoir petrophysical properties, water saturation, CO2 volume fraction, and production pressure differentials. This chart provides essential theoretical support and practical guidance for the development of similar gas reservoirs. |
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| ISSN: | 2095-1426 |