特低渗砂岩储层临界启动渗透率分析

Analysis of the threshold permeability of ultra-low permeability sandstone reservoir

根据特低渗油藏启动压力梯度的概念提出了临界启动渗透率概念.以鄂尔多斯盆地延长组特低渗砂岩储层岩心实验结果为基础,得到了拟启动压力梯度与储层渗透率之间的关系,建立了注采井间驱动压力梯度的变化规律分析.根据拟启动压力梯度与驱动压力梯度的关系,给出了临界启动渗透率的计算方法,以及注采井间临界启动渗透率的变化规律.结果表明,拟启动压力梯度的变化存在临界点;注、采井附近临界启动渗透率下限最低;在两井间中心附近临界启动渗透率下限达到最大.可见,建立有效的驱替压力系统,增大注采井间驱动压力梯度,降低临界启动渗透率,是实现特低渗储层高效开发的主要措施.

According to the concept of threshold pressure gradient,the threshold permeability of ultra-low permeability sandstone reservoir is put forward.The relation between the threshold pressure gradient and reservoir permeability is obtained according to the core laboratory results of the ultra-low permeability sandstone reservoir in Yanchang formation,Ordos Basin.The varying law of the driving pressure gradient between water-injection well and production well is derived.The distribution law of the threshold permeability between water-injection well and production well is presented according to the relationship between the threshold pressure gradient and the driving pressure gradient,which shows that there is maximum of threshold permeability near the center between water-injection well and production well and there are minimums of threshold permeability near the water-injection well and the production well.