fluids Article Klinkenberg-Corrected and Water Permeability Correlation for a Sarawak Carbonate Field Izzat Ahmad, Maqsood Ahmad * and Imtiaz Ali   Citation: Ahmad, I.; Ahmad, M.; Ali, I. Klinkenberg-Corrected and Water Permeability Correlation for a Sarawak Carbonate Field. Fluids 2021, 6, 339. https://doi.org/10.3390/ fluids6100339 Academic Editor: Faik Hamad Received: 15 July 2021 Accepted: 31 August 2021 Published: 27 September 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). Department of Petroleum Engineering, Universiti Teknologi PETRONAS, Persiaran UTP, Seri Iskandar 32610, Perak, Malaysia; izzat_18001840@utp.edu.my (I.A.); imtiaz_17003333@utp.edu.my (I.A.) * Correspondence: maqsood.ahmad@utp.edu.my Abstract: Klinkenberg-corrected permeability (k ∞ ) or water permeability (k w ) is an important input parameter for hydrocarbon reservoir simulation studies. The theoretical concept that a core sample’s k ∞ is comparable to its k w is flawed and has to be verified, since experimental evidence indicates that k ∞ and k w are clearly different. Thus, a series of gas and water permeability measurements were conducted on eight carbonate core plug samples from Sarawak, Malaysia to develop a correlation between both permeability values. The new k ∞ vs. k w correlation clearly proved the differences between both permeability values for all samples. The findings were in agreement with FESEM-EDX and total suspended solids (TSS) analysis, which proved the migration of fines and clay particles that blocked the pore throats, thus reducing k w values. The new k ∞ vs. k w correlation was validated using four different samples from the PETRONS-2 well using its k ∞ values and comparing them with the respective measured k w values. The new correlation will reduce the amount of time and cost needed to obtain absolute liquid permeability values but may be further improved by conducting permeability measurements on more samples from the PETRONS field, which will improve the accuracy of hydrocarbon reservoir simulation of the PETRONS field. Keywords: gas permeability; water permeability; water injection; carbonate reservoir; fines migration; Klinkenberg effect; Klinkenberg-corrected permeability 1. Introduction Absolute liquid permeability value is an important parameter for conducting dy- namic reservoir simulation for any oil and gas reservoir. Industrial practice is to use either Klinkenberg-corrected permeability or water permeability as an absolute liquid permeabil- ity value [1,2]. Theoretically, Klinkenberg-corrected permeability and water permeability of a sample should be similar; however, experimental work shows clear differences between Klinkenberg-corrected permeability and water permeability values. Measured gas permeability is subjected to gas slippage effect, also known as Klinken- berg effect, which can result in overestimation of gas permeability value. This theory was first established by L. Klinkenberg et al. [3]. Later, M. Muskat et al. [4] observed significant differences in permeability values between air and water [5]. Thus, L. Klinkenberg [3] defined that Klinkenberg effect occurs when the mean free path of gas molecules in any porous media approaches the pore dimension. This phenomenon will lead to more fre- quent collision between gas molecules and the pore wall than the collisions between gas molecules, which reduces viscous drag, thus enhancing gas slip flow and increasing the gas permeability values [2,6–8]. As a result, gas permeability must be corrected to Klinkenberg-corrected permeability after applying infinite differential pore pressure [7]. Since at infinite differential pore pressure, gas flows as a liquid-like fluid, theoretically Klinkenberg-corrected permeability of a core sample must be similar to its water permeabil- ity value. This observation is supported by [5,7,9,10], which state that the permeability of a sample should be independent of its pore fluid. However, experimental results have shown that Klinkenberg-corrected permeability and its respective water permeability values show Fluids 2021, 6, 339. https://doi.org/10.3390/fluids6100339 https://www.mdpi.com/journal/fluids