When originally developed, the Koval theory was meant to interpret the core-scale production of oil by a miscible displacement by solvent injection. An essential parameter in the theory is the Koval factor, K_V, which combines both the viscosity contrast effect (E) and the heterogeneity effect (H_K) as K_V = E H_K. The Koval method has done an excellent job of interpreting oil recovery; however, the physical origin of this simple model is not clear. To address the physical significance of these factors, this paper explains a novel approach to derive the Koval factor using petrophysical data and vertical equilibrium theory. The study examines core data from 112 vertical production wells from fields located in the United States and Algeria. The heterogeneity factor is estimated from the flow- and storage-capacity relations, according to the Koval theory. Then, using fractional flow theory and assuming vertical equilibrium, we derive a mathematical expression that conveys the physical interpretation of the Koval factor. The results indicate that the physical explanation of the Koval factor is that of a product of the mobility ratio and the heterogeneity of the reservoir. The Koval factor simplifies computations of oil recovery by transforming the original reservoir to one with uniform layers, in vertical equilibrium, and piston-like displacement within each using only the flow and storage capacities. The physical interpretation of the Koval factor could offer new insights to examine previous results obtained from the theory itself.

最初开发时，科瓦尔理论旨在解释通过溶剂注入的混溶驱替来实现石油的核心规模生产。该理论中的一个重要参数是科瓦尔系数K _V，它结合了粘度对比效应（E）和非均质效应（H _K），K _V  =  EH _K。Koval方法在解释石油采收率方面做得非常出色。但是，此简单模型的物理来源尚不清楚。为了解决这些因素的物理意义，本文解释了一种利用岩石物理数据和垂直平衡理论推导科瓦尔系数的新方法。这项研究检查了来自美国和阿尔及利亚的112口垂直生产井的核心数据。根据Koval理论，根据流量和存储容量关系来估算异质性因子。然后，使用分流理论并假设垂直平衡，我们得出了一个数学表达式，表达了对科瓦尔因数的物理解释。结果表明，Koval因子的物理解释是迁移率与储层非均质性的乘积。Koval系数通过将原始油藏转换成具有均匀层，垂直平衡，且仅使用流量和存储能力在每个油层中产生活塞状位移的方式简化了采油量的计算。Koval因子的物理解释可以提供新的见解，以检验从理论本身获得的先前结果。