The Welge–JBN method for determining relative permeability from unsteady-state waterflood test is commonly used for two-phase flows in porous media. We discuss the theoretical criteria that limits application of the basic Buckley–Leverett model and Welge–JBN method and the operational criteria of the accuracy of measurements during core waterflood tests. The objective is determination of the waterflood test parameters (core length, flow velocity and effluent sampling frequency) that fulfil the theoretical and operational criteria. The overall set of criteria results in five inequalities in three-dimensional Euclidian space of these parameters. For known rock and fluid properties, a formula for minimum core length to fulfil Welge–JBN criteria is derived. For cases where the core length is given, formulae for test’s flow velocity and sampling period are provided to satisfy the test admissibility conditions. The application of the proposed methodology is illustrated by two coreflood tests.

中文翻译：

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两相岩心驱和楔形-JBN 方法的容许参数

Welge-JBN 方法用于从非稳态注水试验中确定相对渗透率，通常用于多孔介质中的两相流。我们讨论了限制基本 Buckley-Leverett 模型和 Welge-JBN 方法应用的理论标准以及岩心注水测试期间测量精度的操作标准。目标是确定满足理论和操作标准的注水测试参数（岩心长度、流速和污水采样频率）。整个标准集在这些参数的三维欧几里得空间中产生五个不等式。对于已知的岩石和流体特性，推导出满足 Welge-JBN 标准的最小岩心长度公式。对于给定磁芯长度的情况，给出了试验流速和采样周期的公式，以满足试验的容许条件。所提出的方法的应用通过两个岩心泛滥测试来说明。