Analysis method of pulse decay tests for dual-porosity cores

Homogeneous models are typically used to analyze the results of pulse-decay tests for low permeability cores. However, this poses a problem because some samples are dual-porosity media with microcracks/macropores and micropores. In this study, numerical simulations were conducted and the results showed that the pulse decay curves of the dual-porosity models are different from those for the homogeneous model. The results indicated that the volumes of the upstream and downstream vessels play an important role in identifying dual-porosity media and the early time and late time are mainly influenced by the storativity ratio and interporosity flow coefficient, respectively. A pressure derivative method was proposed in this work in order to identify dualporosity media at the early time and distinguish the interporosity flow models. This method is applicable for vessel volumes within one-tenth to ten times the pore volume. The proposed method was verified against the experimental data of other researchers.