油藏封存CO_2后扩散逃逸数学模型及实例应用

MATHEMATICAL MODEL OF CO_2 DIFFUSION LEAKAGE AFTER RESERVOIR STORAGE AND ITS SAMPLE APPLICATION

利用油藏封存CO_2是缓解温室效应的重要途径,CO_2扩散逃逸在整个封存体内广泛存在,因此有必要研究扩散逃逸对封存效果的破坏强度。通过理论分析,建立了能够描述油藏封存CO_2后扩散逃逸行为的物理模型和数学模型。结果表明:示范区在1万年累计逃逸量为0.178×104t,1万年累计逃逸量和封存量比值为0.067%,需要1470万年CO_2才能全部逃逸,扩散逃逸对封存破坏甚微。研究结果为CO_2封存效果评价提供了新指标,也为盆地级封存体扩散逃逸量计算提供了方法。

The reservoir CO2 storage is an important way to mitigate greenhouse effect. The CO2 diffusion leakage widely existed in the whole storage course. It is necessary to study the failure strength to storage effect caused by diffusion leakage during the long geological period. Through theoretical analysis,a mathematical model about CO2 diffusion leakage was presented. The amount of CO2 loss was calculated by the physical and mathematical model for CCUS demonstrative region in Jingbian Oilfield. The results showed the cumulative amount of CO2 loss was 0. 178 × 104 tons in ten thousand years. The ratio of loss amount and storage amount was 0. 067%. It could take 1470 × 104 years that the CO2 could loss overall based on diffusion leakage. The diffusion leakage caused minor damage to CO2 storage. The results provided the theory basis for safety evaluation about reservoir storage of CO2,and a way to calculate the mount caused by diffusion leakage for basin scale.