复杂孔隙结构低阻油层含水饱和度解释新方法

A New Method of Explaining the Water Saturation of Low Resistivity Reservoir with Complex Pore Structure

北部湾乌石区流沙港组含砾砂岩储层因受到岩性、分选性、孔喉分布复杂变化的因素,油层出现电阻率比泥岩低、与水层相似的特征,采用多孔微观岩石结构"球管"模型,对孔隙结构与岩石电阻率的响应规律进行了数值模拟,证明岩石复杂的孔隙结构是形成含砾砂岩特有低电阻油层的重要原因。基于复杂孔隙结构导致的实验"弯曲"岩电数据提出了阿尔奇修正方程,修正后的阿尔奇公式适用于具有不同孔隙结构的储层,乌石A油田含砾砂岩储层利用新方法进行评价,能有效提高含油饱和度,且与岩芯实验毛管压力、核磁束缚水更加匹配。

The gravelly sandstone reservoirs of the Liusha Formation in Wushi, Beibu Gulf are subject to complicated changes in lithology, sorting and distribution of pore throats, the resistivity of the oil layer is lower than that of the mudstone and is similar to that of the water layer, the porous tube microstructure model was used to simulate the response of pore structure and rock resistivity. It is proved that the complex pore structure of rock is an important reason for the formation of peculiar low resistivity reservoir of gravel sandstone. The Archie correction equation is proposed based on experimental "bent" rock electrical data caused by complex pore structures. The modified Archie formula is applicable to reservoirs with different pore structures. The Wushi A Oilfield gravel sandstone reservoir is evaluated by a new method, can effectively improve the oil saturation, and the results are more compatible with core capillary pressures and NMR-bound water.