Evaluación de correlaciones empíricas en el cálculo de factor de desviación “Z” para gas natural asociado del oriente ecuatoriano

Abstract

One of the most important and used parameters in petroleum engineering is the gas deviation factor “Z”, this parameter can be measured experimentally. However, several empirical correlations have been developed in order to calculate Z factor for natural gas. The five empirical correlations tested in this document were initially developed for calculating Z factor for non-associated natural gas. Free gas normally contains high quantity of methane and low quantity of impurities. However, in this document the correlations were tested for associated gas, this gas normally contains high quantity of impurities such as carbon dioxide. Since Z factor is required for engineering projects such as designing a gas compressor or gas lines, it is necessary to find out whether a correlation can be used for calculating Z factor for associated gas. Seven current PVT reports were given by Petroamazonas Company, on these reports, experimental values of Z factor by differential vaporization were obtained. Afterwards, the values of gas deviation factors Z were calculated by the five empirical correlations, then, the percentage errors, differences of values and the gas composition effects were analyzed. Two of the five correlations analyzed in this work are relatively current; these correlations were presented in SPE conferences and exhibitions in 2010 and 2013. This document shows that gas deviation factors Z for associated gas can be calculated by empirical correlations and the correlation with the best results is identified.