超低渗浅层砂岩油藏储层非线性渗流模型

以鄂尔多斯盆地渭北地区延长组浅层超低渗砂岩油藏为研究对象,基于储层岩石的应力-应变关系及应力敏感性实验研究认为,流体在渗流过程中,启动压力梯度是动态变化的。利用介质变形、应力敏感性及动态启动压力梯度等参数,采用实验方法、线性回归方法和对比法,根据非达西渗流方程,建立了超低渗浅层砂岩油藏渗流模型。结果表明:超低渗浅层砂岩油藏应力敏感模型与正常埋深储层的应力敏感性模型相似;相对于考虑静态启动压力梯度的超低渗砂岩油藏渗流模型,考虑动态启动压力梯度的超低渗砂岩油藏渗流模型,在同一泄油半径内日产油量小,并且随着泄油半径的增加,日产油量减小幅度越来越大,生产井"压降漏斗"变小、变缓。此结果与油田生产实际相吻合。

Non-linear seepage models for sandstone reservoirs of ultra-low permeability and shallow layers

Based on the study of ultra-low permeability and shallow layers sandstone reservoir in the Ordos Basin and the stress sensitivity experiments for rock stress-strain relationships,the threshold pressure gradient is changing in flowing and the dynamic threshold gradient is defined.Application of experimental methods,linear regression method and comparison method,considering media deformation,stress sensitivity and dynamic threshold pressure gradient,the ultra-low permeability and shallow layers sandstone reservoir seepage model based on the non-Darcy flow equation was established.The results show that the stress sensitivity model of ultra-low permeability shallow sandstone reservoir is similar to the stress sensitivity model of normal buried reservoir,compared with the seepage model of ultra-low permeability sandstone reservoir considering static starting pressure gradient,the gradient of the ultra-low permeability sandstone reservoir seepage model considering the dynamic starting pressure is small at the same drain radius,and with the increase of the oil discharge radius,the daily production oil decreases more and more,and the production well "pressure drop funnel" becomes smaller and smaller.The results of theoretical analysis are consistent with the actual production of oil field.