混合泥质砂岩双电层电导率理论模型

A Theoretical Model Based on Double Layer Conductivity of Laminated and Dispersed Shaly Sand

基于层状泥质与分散泥质砂岩并联导电理论,以及悬浮于电解液中三维周期排列带电球体导电理论,建立了分散泥质和层状泥质同时存在的混合泥质砂岩通用双电层电导率理论模型。分析了模型影响的因素。结果表明,随总含水饱和度的增大,分散粘土阳离子交换容量、胶结指数对混合泥质砂岩电导率与总含水饱和度关系曲线的影响增大;而饱和度指数对混合泥质砂岩电导率与总含水饱和度的关系曲线的影响在总含水饱和度较大时随总含水饱和度的增大而减小。通过2组分散泥质砂岩岩样和1组混合泥质砂岩岩样实验测量数据计算,表明该模型既适用于分散泥质砂岩地层解释,又适用于层状泥质砂岩地层解释,同时还适用于含有分散泥质和层状泥质的混合泥质砂岩地层解释。

Based on the hypothesis that the laminated shale and dispersed shaly sand are parallel conduction, and the conduction theory for 3-dimensional periodic array of charged spheres immersing in electrolyte, a new generalized double layer conductivity model is proposed for laminated and dispersed shale coexisting in shaly sand. The analysis on influence factors of the model shows that the effect of cation exchange concentration QV of dispersed shale and cementation exponent on the relationship curve between formation conductivity Cl and total water saturation Swt increases as the Swt increases; whereas the effect of saturation exponent n on the Cl-Swt curve decreases as the Swt increases in its higher range. Calculation on data of 2 sets of dispersed shaly sand samples and 1 set of artificial synthetic rock samples in laminated and dispersed shaly sand show that this model may be applied not only in dispersed shaly sand but also in laminated shaly sand, also may be applied in mixed laminated and dispersed shaly sands.