Compared with the sandstone reservoirs,acidic volcanic reservoir is characterized by larger pore throat radius ratio and more complex pore structure,which results in larger saturation index.Rock resistivity experimental data show that complex pore structure enhancces complexity of the physical relationship between resistivity and water saturation and fixed rock electrical parameter is difficult to reflect the complexity of the volcanic rock pore structure.Through researching rock electrical experimental data and the impact of the pore structure on the rock electrical parameters,we introduce a non-homogeneous equilibrium constant C,first propose a new resistance increment rate function of the reservoir with bigger pore throat radius ratio.When Sw is small,influence of saturation index n on calculation is big; when Sw is large,the influence of nonhomogeneous constant C on calculation is also big.The acidic volcanic reservoir with bigger bonding index mm has the best correlation with the reservoir quality factor.When n is more than 3,the acidic reservoir has better correlation with the pore throat radius ratio.Changes of m and n reflect the porestructures.We have established a new gas saturation interpretation model based on pore structure and determine model parameters.The new model has reduced the influence of pore structure on the calculation of gas saturation and revealed the influence of pore structure on the physical relationship of the resistivity and water saturation.The model is applied to gas saturation explanation of 35 wells in the studied area,and the calculation result is excellent.%与砂岩储层相比,研究区酸性火山岩储层具有孔喉半径比大及孔隙结构更加复杂的特征,导致该类储层饱和度指数较大.岩电实验资料研究表明,孔隙结构复杂使Rt与Sw的物理关系变得复杂,且固定的岩电参数难以反映孔隙结构的变化.通过研究岩电实验数据以及孔隙结构对岩电参数的影响,引入非均质平衡常数C,提出对于孔喉半径比大的储层电阻增大率函数的新形式,指出饱和度指数n在储层含水饱和度Sw较小时对计算结果影响较大,非均质常数C在储层Sw较大时对计算结果影响较大.酸性火山岩储层胶结指数m较大时与储层品质指数相关性最好；n＞3时与孔喉半径比相关性最好；m和n的变化反映孔隙结构的变化.采用变模型参数的方法反映储层孔隙结构变化,建立基于孔隙结构的饱和度解释模型,确定参数的计算模型.该模型较好地解决了孔隙结构对饱和度计算的影响,揭示了孔隙结构对电阻率与含水饱和度之间物理关系的影响.在研究区35口井中进行应用,效果较好.
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