Summary: Permeability is an important parameter to evaluate reservoir rock quality, which determines the flow capacity of the reservoir. Probe permeametry has been conducted on core samples as a technique to obtain quick permeability data at a thick density of measurement points and is suitable for various rock types. Since the test method is performed on core samples containing liquid phase at ambient condition, the probe permeability values are usually different from gas/air permeability values at the same measuring points. In this study, a multi-purpose gas permeameter upgraded by the Vietnam Petroleum Institute (VPI) was used to measure probe permeability and gas permeability for 3 different sample groups (the good quality core sample, tight core sample and sidewall core sample with 1.5 inch diameter). The results allowed us to determine the probe permeability variability, namely that the probe permeability values were usually lower than the air permeability but the gas permeability and the probe permeability profiles were still close to each other. The difference between the two increased at low probe permeability. Fracturing in the samples likely caused the probe permeability to be higher than the gas permeability.

Key words: Air permeability, probe permeability, multi-purpose gas permeameter, steady-state flow, core sample.