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孔隙几何形状影响岩石电导率的方式,对沉积岩油气潜力评价非常重要。实际上,所有测井地层评价都采用了至今从未有人给出过满意物理基础的阿尔奇经验公式。我们根据由导电相几何形状决定的含水岩石电流传导效率导出的新模型,作为阿尔奇公式的替代形式。在岩石孔隙系统中,整个导电相的电流密度是不均匀的。数值模拟研究表明,在孔隙喉道处电流密度大,在孔隙系统隔离部分中近乎停滞的空间,电流密度低。岩石电效率是孔隙系统中所有含水部分产生的平均功率一个长度和岩石含水体积与岩石相同的直管中产生的功率之比。它并不受岩石中水的总体积影响,仅由孔隙系统中孔隙几何形状和油气所导致的不均匀电流分布所决定。电效率可以通过先验给定导电相的几何分布来计算。可用电效率和含水量的经验关系根据测井资料计算油气饱和度。
The way in which pore geometry affects rock conductivity is very important for the evaluation of hydrocarbon potential in sedimentary rocks. In fact, all logging formation evaluations use the Archie experience formula that has never given anyone a satisfactory physical basis before. We derive a new model based on the current conduction efficiency of aqueous rock, determined by the geometry of the conductive phase, as an alternative to the Archie formula. In rock pore systems, the current density of the entire conductive phase is not uniform. Numerical simulations show that the current density is high at pore throats and near stagnation in the isolated part of the pore system, and the current density is low. Rock electrical efficiency is the ratio of the average power produced by all the water-bearing parts of a pore system to a length and the power produced in a straight tube of rock with the same volume of water as the rock. It is not affected by the total volume of water in the rock, but only by the pore geometry in the pore system and by the uneven current distribution caused by the oil and gas. Electrical efficiency can be calculated by a priori given the geometric distribution of the conductive phase. Empirical relationships between electrical efficiency and water cut can be used to calculate hydrocarbon saturation from well logs.