Cent. Eur. J. Eng. • 1(1) • 2011 • 81-88 DOI: 10.2478/s13531-011-0011-z Central European Journal of Engineering Prediction of Moisture Content of Natural Gases Using Simple Arrhenius-type Function Research Article Alireza Bahadori ∗ School of Chemical and Petroleum Engineering, Curtin University, GPO Box U1987, Perth, WA, 6845 Australia Received 22 January 2011; accepted 16 February 2011 Abstract: Natural gas extracted from underground reservoirs is saturated with water. The accurate prediction of moisture content in natural gas is extremely important. The presence of water vapor can lead to potentially disastrous consequences. The lifetime of a pipeline is governed by the rate at which corrosion occurs, which is directly linked to the available moisture in the gas resulting in oxidation. In addition, the formation of hydrates due to presence of water in natural gas can lead to safety hazards to production/transportation systems and to substantial economic risks. In this paper, an attempt has been made to develop an easy-to-use Arrhenius-type asymptotic exponential function combined with the Vandermonde matrix to arrive at an appropriate estimation of saturated water content of sour natural gases for pressures up to 69000 kPa and the temperature range between 20 to 180˚C. Percent average absolute deviation of the proposed method is found to be around 2%, demonstrating the excellent performance of the developed predictive tool. The tool will be of great practical value for chemical and petroleum engineers to have a quick check on the water content of sour natural gases at various temperatures and pressures without performing any experimental measurements. Keywords: Natural gas • water content • Arrhenius function • predictive tool • Vandemonde matrix • Matlab program © Versita Sp. z o.o. 1. Introduction Moisture removal is a key stage of natural gas condi- tioning and processing prior to sale and its efficiency is important in order to satisfy fiscal contractual obligations and to ensure that the gas is safe to transport and con- tains the right properties for subsequent use [1]. When the gas is produced there is a simultaneous production of water as well. Some of this water is produced water from ∗ E-mail: alireza.bahadori@postgrad.curtin.edu.au, Tel: +61 8 9266 1782, Fax: +61 8 9266 2681 the reservoir directly [2]. In the transmission of natural gas, further condensation of water is problematic. It can increase pressure drop in the line, often leading to corro- sion problems and gas hydrate formation [1, 2] which can reduce pipeline flow capacities, blockages and potential damage to process filters, valves and compressors. Such hydrates are caused by the combination of excessive wa- ter vapor with liquid hydrocarbons, which may condense out of the gas in the course of transmission to form emul- sions that, under process pressure conditions, are solid masses. There are numerous methods available for deter- mining water content of natural gases [3–8]. In some of these models the vapor pressure of pure water is required 81