孔隙压力对微裂隙低渗透介质变形的影响实验研究

应力敏感作用对低渗透储层的渗流有重要的影响。为了明确微裂隙低渗透储层的应力敏感特征,首先分析了储层的变形机理;然后通过改变孔隙压力实验,模拟测定微裂隙低渗透储层的应力敏感特征;最后分析了应力敏感对生产的影响。研究表明:超低渗透研究区微裂隙比较发育,使其储层砂岩具有应力敏感特征;渗透率模数能够较好的描述研究区的介质变形特征;孔隙压力降低,超低渗透岩心渗透率下降幅度远远高于其它各类储层岩心,表明油藏开发过程中,超低渗储层介质变形非常严重。随着生产压差增大,超低渗介质变形油藏单井产能随之增加,油井开采过程中,选择合理的生产压差是减小介质变形对油井产能造成伤害的关键。

The Effect of Pore Pressure on the media deformation of Microcrack Low Permeability Reservoir

The stress sensitivity has an important effect on the seepage of low permeability reservoir. In order to study the stress sensitive features of microcrack low permeability reservoir, we first analyzed deformation mechanism of the reservoir and then the experiments were conducted under different pore pressure to reveal the deformation features. At last, the influence of deformation on the production was analyzed. The results show that: The microcracks are developmental in ultra-low permeability area leading to obvious stress sensitive features. The permeability modulus can describe the permeability stress sensitive characteristic well. The permeability of ultra-low permeability cores declines more greatly than that of high permeability as the pore pressure reduces. It indicates that the media deformation of ultra-low permeability reservoir is very serious. As the production differential pressure increases, the productivity in ultra-low permeability reservoir increases, so the oil wells should be produced in reasonable production differential pressure in order to reduce the deformation damage to the oil well productivity.