西峰油田特低渗弱亲油储层微观水驱油特征

目的研究特低渗弱亲油储层水驱油过程、水驱油效率及其影响因素。方法运用岩心实验和真实砂岩模型实验研究方法。结果西峰油田特低渗弱亲油储层微观水驱油效率平均49．3％，无水期驱油效率21．3％；孔隙中水主要是以活塞式驱油为主，非活塞式驱油少见；微观残余油主要以绕流和油膜形式存在；提高注水压力可使该类储层微观水驱油效率提高12％，并且当注水倍数大于2PV时对最终水驱油效率影响不大；表面活性剂能够提高此类储层的微观水驱油效率10％左右。结论弱亲油储层与亲水、弱亲水、中性特低渗储层的微观水驱油效率相当或无显著的差别，但无水期微观水驱油效率明显低于亲水性储层；孔隙结构是决定特低渗储层微观水驱油效率的主要因素。

Micro-flowing behaviors of water displacing oil in low permeability weak oil-wet reservoirs, Xifeng Oilfield

Aim To study the water displacing oil efficiency of weak oil-wet low permeability reservoirs, displacing process and affecting factors.Methods Core and micromdel experiment methods are used.Results The average water displacing oil efficiency of low permeability weak-oil wet reservoirs in Xifeng Oilfield is 49.3%, the water displacing oil efficiency in water free oil production period is 21.3%. Piston-like displacement is the main mechanism of water displacing oil in pore-throats.Residual oil is at existents of oil membrane and by-pass oil. Improving the pressure of water injection, water displacing oil efficiency will be increased by 12% at most. When water injection volumes are more than 2PV, it does not effect the water displacing oil efficiency seriously. Surfactants can improve the water displacing oil efficiency by about 10%.Conclusion It is the same as other wettability low-permeability reservoir's water displacing efficiency and the water displacing oil efficiency in water free oil production period is lower than low permeability water-wet reservoirs obviously. The pore structure is the most important factor that effects water displacing efficiency.