Comparative Evaluation of Laboratory Permeability Measurement Approaches of a Carbonate Formation

As the phenomenon of gas slippage in rock pores is considered, the relationships between liquid equivalent permeability and absolute air permeability of 171 core plug samples of a carbonate reservoir from Dalan Formation were evaluated. Conventional absolute gas permeability measurement is generally much cheaper and faster than liquid permeability measurement. In this study, a comparative laboratory investigation of the permeability determination of carbonate rocks is represented. Air permeability, Klinkenberg corrected, and absolute water permeability experiments were performed. The gas permeability measurements at steady-state, unsteady-state, atmospheric flow, and back pressure flow modes were also examined in this research. The samples were divided into two permeability ranges of 0.1 to 1 mD and 1 to 1000 mD. The exponential relationship provided the best fit between absolute water, Klinkenberg, and air permeability values. It is best to use the constant back pressure method for samples with higher permeability to avoid errors in calculating the Klinkenberg factor, b. The Klinkenberg permeability was up to 7.2 times larger than the absolute water permeability due to the polar nature of water molecules. These results are helpful in providing a better basis for the prediction of Klinkenberg and water permeability values for this formation and similar carbonate reservoirs than the available correlations.