低渗透油藏水锁伤害机理及解水锁实验研究

Study of Water Locking Damage Mechanism and Water Unlocking of Low Permeability Reservoir

针对地层压力低(压力系数小于1)、油井含水率低(小于50%)的低渗油井,水锁伤害普遍存在的问题,研究了毛细管效应和贾敏效应对产生水锁现象的机理认识。通过实验数据结果分析,得到了水锁现象与渗透率的关系,即:渗透率越低,水锁程度越严重,10.00mD以下的岩芯,压力升高值基本在25%左右,而大于10.00mD的岩芯压力升高值在15%左右。注入表面活性剂后,解除水锁效果非常明显,特别是渗透率越低,效果越明显,最高驱替压力值下降幅度达到了近50%。说明表面活性剂对解水锁具有很好的效果。

Water locking phenomenon is the typical of low and extra low permeability reservoir. Which is a common problem in low permeability oil wells, and is of low formation pressure （pressure coefficient less than 1 ）and of low water cut （less than 50%）. Capillary effect and Jiamin effect is the main mechanism of the occurrence of water locking phenomenon. Through experimental analysis we find out that the lower the permeability is, the worse the water locking degree is. The pressure of the core which is less than 10 mD rise about 25%. But the pressure of the core which is more than 10 mD rise about 15%. The injection of a surfactant displayed remarkable water unlocking effect, especially when the permeability is low, and the maximum displacement value of pressure drops by almost 50%, which proves that surfactant is very effective in water unlocking.