Compressibility Factor Correlation for the Niger Delta Gas

Abstract Gas compressibility factor (z) is very essential in gas engineering. Apart from PVT Lab measurements and its subsequent calculations, correlations exist for the estimation of Niger Delta gas z-factor but the correlations were developed with data of gas samples from regions different from the Niger Delta so they do not always predict Niger Delta gas z-factor with good accuracy hence the need for a new correlation that would predict Niger Delta gas z-factor with high accuracy. Correlation for estimating the z-factor of Niger Delta gas was developed in this work using Microsoft Excel Data Analysis Tool and SPSS Statistics Software. 300 data points from PVT analyses of 14 fluid samples from Niger Delta were obtained for this study. The existing correlations were evaluated for Niger Delta gas z-factor to determine the best performing correlation using statistical parameters like percent mean relative error, %MRE, percent mean absolute relative error, %MAE, standard deviation, SD, correlation coefficient, R and performance plots. The developed correlation was compared with the best performing correlation selected using the same parameters. The new correlation was found to perform better than the best performing existing correlation selected, the new correlation had lower %MRE, %MAE and SD; higher R and better performance plot than the best existing correlation. The developed correlation found to outperform the existing correlations is for the Niger Delta gas but can be used for all types of gas with properties falling within the range of data used for its development.