芳深9井CO_2气藏CO_2气扩散特征及损失量

Diffusion characteristics and loss amount of carbon dioxide gas in FS9 well

为了准确评价CO_2气藏资源,研究了CO_2气在地下的扩散机制;分析了CO_2气在地层剖面上的扩散特征;并根据芳深9井CO_2气各扩散参数,估算了该气藏的累积扩散损失量。结果表明,CO_2气分子在地层水中主要以水合形式存在,在水中的溶解能力主要受其所处温度、压力条件及水矿化度的影响。随着CO_2气在地层水中溶解能力的变化,CO_2气在地层剖面上的扩散分为3段,小于0.50km埋深范围内,CO_2气向上扩散,作用较强;0.50～1.25km埋深中,CO_2气向下扩散;大于1.25km埋深,CO_2气向上扩散,作用较弱。芳深9井CO_2气藏最大损失量约为23.5×10~8m^3,约占其地质储量的17.5％。

To evaluate the resources of carbon dioxide gas, this paper discusses the diffusion mechanism of carbon dioxide gas in strata, analyzes the diffusion characteristics of carbon dioxide gas in strata section. According to each diffusion parameters of carbon dioxide gas reservoir in FS9 well, this paper estimates the total loss amount of carbon dioxide gas diffusion in the gas reservoir. The result indicates that the molecules of carbon dioxide exist in water in the hydration form. The dissolving ability in water is affected by temperature, pressure and salinity. According to the change of solubility of carbon dioxide gas in water, the diffusion of carbon dioxide in strata section is divided into three parts, carbon dioxide gas diffuses strongly upward when its depth is less than 0. 5km, and diffuses downward when its depth is within 0. 5km to 1. 25km. Carbon dioxide gas diffuses weakly upward when its depth is more than 1. 25km. The maximum loss amount of carbon dioxide gas diffusion in FS9 well is 23. 5X108 m3. It is a-bout 17. 5% of its geological reserve.