【摘要】 随着油气藏的开采,储层的应力状态发生变化,从而引起储层孔隙度及渗透率发生相应变化。大量的实验表明,孔隙度随有效应力的变化而产生的变化范围较小,而渗透率的变化范围较大。应用Terzaghi有效应力理论得到的结论是低渗透砂岩具有很强的渗透率应力敏感性以及弱孔隙度应力敏感性。引入双重有效应力理论,对孔渗随应力的变化关系进行重新校正和评价,表明随着应力变化,低渗透砂岩储层的孔隙度变化不大,而渗透率变化较大。而用双重有效应力计算出来的结果比用Terzaghi有效应力计算结果要小得多,表明低渗透储层对有效应力并不是非常敏感的,这在于按照双重有效应力理论,在计算本体有效应力时已在孔隙压力前乘上了一个修正因子,故在开发过程中地下岩石有效应力的变化范围就减少了很多,所以渗透率的变化幅度也就相应地减小了很多。更多还原

【Abstract】 The reservoir stress state will change resulting from the development of reservoir, which induces the change of reservoir’s physical properties such as permeability and porosity. The change resulting from the change of effective stress of porosity is smaller than that of permeability. By Terzaghi effective stress principle, it is concluded that the low-permeability sandstone has strong stress-sensibility for permeability and weak stress-sensitive for porosity. According to the dual effective stress theory, the relation between porosity/permeability and effective stress is re-corrected and re-evaluated. The results show that the change of permeability is larger than that of porosity as the effective stress changes in the sand reservoirs with low permeability. The results calculated by the dual effective stress are much smaller than that calculated by Terzaghi effective stress. It implies the low-permeability reservoirs are not stress sensitive. It is why the conclusion is produced that according to the dual effective stress theory the pore pressure is multiplied by a correction factor while calculating the effective stress, which makes the changing range decreasing much for the effective stress, so does that for the permeability.更多还原