特低渗透砂岩油田开发贾敏效应探讨--以鄂尔多斯盆地中生界延长组为例

Jamin Effect in the Ultra-low Permeability Sandstone Oil Field Development:An Example from Yanchang Formation of Mesozoic Strata

鄂尔多斯盆地中生界延长组储层是典型的特低渗透砂岩储层,属于细孔微喉型,非均质性强,注水开发中贾敏效应异常强烈。通过微观砂岩模型水驱油实验发现贾敏效应是油田注水开发中不可忽视的阻力。实验中贾敏效应主要表现为:①水驱油过程中注水压力不断变化;②贾敏效应的循环作用;③油滴受贾敏效应作用无法运移;④贾敏效应致使水驱中油相渗透率急剧下降,水相渗透率缓慢上升。通过注采系统提高注水压力无法消除贾敏效应,因此在注水开发中要以预防贾敏效应为主。

The Yanchang Formation of Mesozoic strata in the Ordos Basin is characterized by ultra-low permeability with minute pores and microscopic throats, which results in severe Jamin effect in the lithologically heterogeneous formations. By the laboratory work of real sandstone micro-models, the resistance of Jamin effect should not be ignored. The Jamin effect is manifested in the following： when the pressure changes continuously, the oil drop cannot be removed and the oil relative permeability curve sharply descends, while the water relative permeability curve slowly ascends. However, the improvement of the injection pressure will not prevent Jamin effect. Hence, the prevention of this effect sould be emphasized in the waterflood development.