Analytical models for capillary imbibition: Multidimensional matrix blocks

This study has evaluated numerous analytical models for countercurrent capi llary imbibition for use as matrix-fracture transfer functions in waterfloo d models for naturally fractured reservoirs. Relationships between the vari ous models were developed and were used to reformulate the models into comm on terms so they could be compared. Laboratory imbibition data were obtaine d to validate the models. From this analysis, the strengths and weaknesses of each model were determined. An extended-square-root model was the best m odel for the early-time period when the finite size of the matrix block did not impact imbibition. An exponential model provided the best overall mode l for imbibition through the entire imbibition process, although it was not accurate for the very early times.