凝析油蒸发动态特征  

Re-vaporization and retrograde vaporization of the liquid condensate

作　　者：吴蕾[1] 袁士义[2] 胡永乐[2] 刘合年[2] 李海平[3] 

机构地区：[1]石油大学(北京) [2]中国石油勘探开发研究院 [3]中国石油天然气股份有限公司

出　　处：《石油勘探与开发》2004年第2期122-124,共3页Petroleum Exploration and Development

摘　　要：凝析气藏开采到压力降到露点压力以后 ,会在储集层中产生液态凝析油 ,凝析油饱和度常小于临界凝析油饱和度 ,凝析油黏度大会产生流度差异效应 ,往往导致凝析油滞留在储集层中。由于相平衡效应 ,会产生 3种不同的凝析油蒸发动态情形 :①压力低于最大反凝析压力后的凝析油蒸发效应 ;②保持压力过程中的凝析油再蒸发效应 ;③注入流体使地层压力上升过程中的凝析油反蒸发效应。在降压开采过程中 ,液态凝析油体积逐渐减小 ,这主要是由于整个压力衰竭过程中平衡气相的中间组分和重组分含量越来越少 ,为了达到相态平衡 ,液相中的相应组分重新分配到气相中 ,从而出现凝析油的蒸发现象。富凝析气藏常常采用注气开发 ,注入气体与原始凝析气藏流体进行组分交换 ,使凝析油在地下蒸发现象明显 ,注入干气不仅能蒸发凝析油中的中间烃类 ,而且也能蒸发C2 0 + 以上的重烃。实际凝析气藏在高注采比条件下 ,产出凝析油中较重组分含量增加幅度较大 ,说明当凝析油析出后 ,通过注气提高地层压力 ,可以将反凝析的重组分部分反蒸发而采出。图 2表 1参The liquid phase often condenses in the reservoir when the fluid pressure drops below the dew point pressure. The condensate often remains as an immobile phase in the porous media with low recovery because the saturation point of liquid condensate is usually less than that of the critical condensate and the mobility effect occurs due to larger viscosity of condensate. Due to the effect of phase equilibria, the reservoir fluid may exhibit one, or a combination, of the following three types of vaporization: ① the re-vaporization of condensate, when the pressure is below the maximum condensation pressure, ② the equilibria revaporization due to the extraction effect of lean gas during gas injection, ③ the retrograde vaporization of condensate, when the reservoir pressure builds up as a result of more voids being replaced by injected gas. With pressure depletion, the liquid volume will be reduced continuously. For rich gas condensate reservoirs, due to the component exchange between the injection gas and the condensed liquid, the re-vaporization is obvious. The tests show that the lean gas can vaporize the intermediate as well as the heavier fraction such as C_(20+). In the natural reservoir, under the condition of high injection-production ratio, the composition of heavy components will increase and the heavy components can be extracted to the surface through partial vaporization.

关 键 词：凝析气 反凝析 定容 蒸发 反蒸发 注气 

分 类 号：TE311[石油与天然气工程—油气田开发工程]