Developing a simple and accurate correlation for initial estimation of hydrate formation temperature of sweet natural gases using an eclectic approach

Formation of natural-gas hydrates which are crystalline solids composed of water and gas has been a problem to the natural-gas industry in production, processing facilities and transportation and caused substantial economic risks. Therefore, in order to overcome hydrate-related issues, it is important to predict the temperature and pressure under which gas hydrates form. Since the start of hydrates studies, several correlations have been proposed to predict their formation temperature (HFT) under circumstances of different known data such as indeterminate gas composition. However; most of these models have failed to give a good prediction of HFT over a wide range of pressure and gas gravity variation; furthermore, the presented models often require complicated and long computations. The purpose of this study is to present an accurate and simple correlation with only one set of coefficients, achieved using a novel fitting method which can apply for the large range of temperatures (273-299 K), pressures (350-30,000 kPa) and molecular weights (16-29 g/mol). The new proposed correlation shows to be the most accurate one among all the available correlations. The coefficient of determination (R2) of this new formula is 0.9874 and the maximum absolute error is 1.3% for 545 experimental data. The results of the correlation are compared with seven widely used correlations along with a neural network model for predicting hydrate formation conditions using back propagation.