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最近10年,在东南亚海域和南美东海岸发现一些高含CO_2的带有CO_2气顶的油环或底油油藏,对油气藏开发技术带来新的挑战。CO_2对原油中的中轻质组分的萃取作用显著,造成气顶气区以CO_2组分为主,底油或油环中的C_(7+)以上组分明显偏高,流体组成与分布特征既不同于传统的凝析气藏,又不同于混相驱油藏。基于油藏烃类取样样品组成,按照Kay混合法则、物质守恒原理及Span&Wagner状态方程等建立了CO_2充注改造前油藏流体组成恢复方法,恢复出古油藏烃类流体组成与分布,应用油藏数值模拟方法模拟CO_2充注改造油藏过程,达到平衡后获取高含CO_2油气藏的流体组成与空间分布特征。应用该方法对某深水高含CO_2油藏流体组成和空间分布进行了预测,预测结果与油藏取样结果基本相符,表明该方法是可行的。
In the recent 10 years, some oil-ring or base oil reservoirs with CO 2 gas cap with high CO 2 content were found in the sea area of Southeast Asia and the east coast of South America, which posed new challenges for the development of oil and gas reservoirs. CO_2 had a significant effect on the extraction of light and medium components in crude oil, which led to the CO_2 component in the gas cap zone, the C_ (7+) component in the bottom oil or oil ring was obviously higher, and the fluid composition and distribution Characteristics are different from the traditional condensate gas reservoir, but also different from the miscible displacement reservoir. Based on the sample composition of hydrocarbon samples collected from reservoirs, the fluid composition recovery method of pre-charge CO2 reservoir was established according to Kay’s law of mixing, conservation of matter and Span & Wagner equation of state to recover the composition and distribution of hydrocarbon fluids in the ancient reservoirs. The application of oil The reservoir numerical simulation method simulates the filling process of CO2 reservoir to achieve the composition and spatial distribution of the fluid in the high CO2 bearing oil reservoir after the equilibrium is reached. The method is applied to predict the fluid composition and spatial distribution of a deep-water high CO_2 reservoir. The prediction results are basically consistent with the reservoir sampling results, indicating that this method is feasible.