重整化群法在静北潜山油藏储层渗透性研究中的应用

PERMEABILITY OF FRACTURED RESERVOIRS IN THE JINGBEI BURIED HILL POOL, CENTRAL LIAONING PROVINCE: A RENORMALIZATION GROUP APPROACH

重整化群法与渗滤理论的结合是目前研究裂缝网络连通性的有效方法。该方法在静北潜山油藏裂缝性储层中的应用结果表明 :①储层的总体裂缝概率在岩心尺度上都超过临界值 ,裂缝网络完全能够自由渗滤 ,这意味着储层总体上等价于高孔隙度的砂岩层 ;②断层 (包括确定断层和小断层 )的存在对储层渗透率有着显著影响。当断层起遮挡作用时 ,在井网间距的尺度上储层渗透率只为数毫达西 ,因而不利于地下流体的侧向流动 ;相反地 ,当断层起导流作用时 ,储层渗透率随着观察尺度的加大而增加 ,且在较大的尺度下 ,断层网络自身能够进行自由渗滤。实际情形应该介于这两种极端情形之间 。

The renormalization group method coupled on the percolation theory provides an effective way to calculate fracture connectivity and to describe the scale dependence of rock permeability. An example is taken from the fractured reservoirs of sandstone and dolomite in the Jingbei buried hill pool within central Liaoning province, Northeast China. In the cores of A67 well, total fracture probabilities calculated within the core scale may be larger than 0.5 or the critical probability for 2D fracture network. This indicates the utmost connection of fracture networks in reservoirs, thus corresponding to the abundance of pores in sandstones. On the other hand, these fractured reservoirs are overprinted by numerous faults in the pool. Whether conductive or not, small faults referred to as those under the resolution, will undoubtfully have an impact on the reservoir permeability. Modified renormalization group method is herein used. If small faults are inconductive,calculated permeabilities decrease from 22mD in fractured matrix to several mD within the scale of well spacing; and if conductive, increase with the observation scale.