低渗透高饱和油藏能量合理补充时机研究

Study on reasonable energy supplement timing for low permeability and high saturation reservoirs

陈民锋 赵梦盼 王敏 盖建 时建虎

中国石油大学（北京）石油工程学院，北京 102249

College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China

低渗透高饱和油藏储层具有启动压力梯度，原油饱和压力较高，地层饱和压差较小，油藏开发受到诸多条件的限制。文中基于低渗透高饱和油藏基本渗流特征，分析了衰竭开发阶段储层流体不稳定渗流过程，采用稳定逐次逼近法，求解包含启动压力梯度项的渗流方程；考虑启动压力梯度影响，在低渗透高饱和油藏早期开发阶段，建立油藏能量合理补充时机的确定方法。结合实际油田情况，分析了衰竭开发阶段储层中压力分布和油井产量变化规律。研究表明，要综合考虑储层性质和流体条件的影响以及油田开发条件的要求，确定合理开采速度下的能量合理补充时机，才能获得较好的开发效果。

Development of low permeability and high saturation reservoirs is restricted by more conditions because of the existence of threshold pressure gradient, high saturation pressure and low formation-saturation pressure difference. Based on the characteristics of porous flow in low permeability and high saturation reservoirs and using the method of steady-state successive approach, this paper analyzes the unsteady flow driven by natural elastic energy and gets the solution of flow equation which takes into account the influence of threshold pressure gradient. During the early development stage of low permeability and high saturation reservoirs, a method which takes into account the effect of threshold pressure gradient is built for the determination of reasonable energy supplement timing to meet development requirement. Combining with the practical examples in oilfield, the change of reservoir pressure distribution and well production rate during natural elastic energy stage is determined. The results indicate that after making an all-around consideration of the impact on reservoir property, fluid condition and development condition, the reasonable energy supplement timing under rational exploitation velocity is determined and the reservoirs can be exploited more effectively.

10.6056/dkyqt201404013