Use of geology in the interpretation of core-scale relative permeability data

A number of factors, such as wettability, pore size distribution and core-scale heterogeneity, are known to affect the measured relative permeability in core plug samples. This paper focuses on the influence of geological structure at the laminaset scale on water-oil imbibition relative permeability curves. The endpoint positions and curve shapes vary as a function of the type of internal heterogeneity, the flow rate, and the assumptions on the pore-scale petrophysics (e.g. wettability). Interaction between the capillary forces and heterogeneity can occur at the cm-dm scale which results in widely varying two-phase flow behaviour for rocks with the same single-phase permeability. The geometry of heterogeneity as expressed in standard geological descriptions (e.g. cross-laminated, ripple-laminated, plane-laminated) can be translated into features of the expected relative permeability behaviour for each rock type, thus aiding the interpretation of relative permeability data. We illustrate how our findings can help to interpret sets of relative permeability data from the field, using some examples from the Admire sand, El Dorado Field, Kansas.