不饱和油藏存在气顶的可能性探讨

Possibility Discussion of Gas-Cap in Unsaturated Oil Reservoir

通过油藏流体物性实验及带气顶稠油油藏特征研究,明确了M油田的流体性质及油藏特征,从而建立稠油氧化带模式,确定该油藏为带气顶、底水的不饱和特稠油油藏。研究结果表明,在长期油水气相互作用的过程中,油藏边缘形成了类似壳体的氧化带,其中胶质、沥青质含量高,并具有封隔作用,使原油氧化产生的伴生气难以回溶到地层原油中,在一定的储盖条件下形成气顶。该研究成果打破常规流体分析的思路,明确了油藏流体特征,可为油藏开发策略提供重要的参考。

Laboratory fluid test and reservoir property analysis of heavy-oil reservoir with gas-cap are used to determine the fluid and reservoir properties in M Oilfield. A heavy-oil oxidation zone mode is established and this reservoir is considered as an unsaturated extra-heavy oil reservoir with bottom-aquifer and gas-cap. Research shows that an oxidation zone with shell shape is created in the reservoir edge due to the long-term oil-water-gas interaction. This oxidation zone with high content of resin and asphaltene is taken as a barrier to prevent the associated gas generated by crude oil oxidation from migrating to formation oil,and a gas-cap is created by this part of associated gas. Conventional fluid analysis is broken through by this research,which could determine reservoir fluid properties and provide significant references for reservoir development strategy.