疏松砂岩油藏出砂应力敏感实验研究

Experimental Study on Sanding Stress Sensitivity in Unconsolidated Sandstone Reservoirs

为研究疏松砂岩储层应力敏感特征,模拟出砂对储层渗透性的影响,制作了全直径人造疏松砂岩油藏岩心,利用研制的疏松砂岩油藏应力敏感测试实验装置,采用不同驱替压差和驱动流速,模拟研究储层不出砂及出砂情况下储层渗透率和相对渗透率的变化规律。实验结果表明,疏松砂岩储层具有较大的压实空间,当轴向压缩率超过2%以后,渗透率的下降幅度均超过50%;在轴向压缩率范围内,两相共流区均从55%降低到20%,但在同样的轴向压缩率下,出砂会降低两相共流区的缩减速度。研究表明,疏松砂岩储层渗透率具有较强的应力敏感特征,适度出砂可以减小渗透率的降幅,降低油水两相共渗区的缩减速度,在一定程度上有助于保持油井产能。

In order to study stress sensitivity of unconsolidated sandstone reservoirs and simulate the influence of sanding to reservoir permeability,on the basis of man-made loose sand core and using experi- mental apparatus for stress sensitivity test, the variations in reservoir permeability and relative permeability under sanding or non-sanding conditions were simulated at various pressures and flow velocity in the stress sensitivity experimental study by using Synthetic core. It is indicated that permeability drop would be over 50 %when the axial deformation exceeds 2 %due to its large degree of compaction for the unconsolidated sandstone reservoir,and the two phase flow zone reduced from 55 % to 20% while sanding could lower the reduction speed of the two phase zone. So the results showed that unconsolidated sand reservoir has strong stress sensitivity and moderate sanding could slow permeability drop and lower the reduction speed of the two phase flow zone so as to maintain well production capacity to some extent.