A general correlation for predicting the suppression of hydrate dissociation temperature in the presence of thermodynamic inhibitors

Predicting hydrate stability zones of petroleum fluids using sound velocity data of salt aqueous solutions

“…Table 1 shows maximum weight percents of salts and number of data of the learning sets on hydrate suppression temperature and sound velocity in aqueous solutions used in this study. All the aqueous systems were assumed to be in contact with methane and the hydrate suppression temperatures for these systems were calculated at 20 MPa from a previously reported predictive method [10]. The reliability of this predictive method for estimating hydrate inhibition effects of inhibitors has already been demonstrated in many publications [20].…”

“…15 engineering purposes [1]. It should be mentioned that the hydrate suppression temperature is generally a function of various factors such as pressure and petroleum fluid compositions [10]. These factors can be ignored for engineering purposes in calculating hydrate suppression temperatures due to the presence of salt aqueous solutions.…”

“…The results coming from a general predictive method [10] for hydrate suppression temperature due to the presence of salt in aqueous solution were used as pseudo-experimental hydrate suppression temperature. All the aqueous systems were assumed to be in contact with methane and the hydrate suppression temperatures for these systems were calculated at 20 MPa from the predictive method [10]). experimental hydrate suppression temperatures employed for training and calculated hydrate suppression temperatures from the ANN equals to 0.6 K).…”

“…The feed-forward (back propagation) neural network (FNN) method with a modified Levenberg-Marquardt algorithm [5][6][7][8] is employed among various ANNs reported in the literature, as it is known to be effective to represent the nonlinear relationships between variables in complex systems and can be regarded as a large regression method between input and output variables [9]. The predictions of a comprehensive predictive method [10] for hydrate suppression temperatures (the difference between hydrate dissociation temperature in the presence of salt aqueous solution and hydrate dissociation temperature in the presence of distilled water at a given pressure) [10] as pseudo-experimental data and literature data [11,12] of sound velocity in aqueous phase due to the presence of salt (NaCl, KCl, NaBr, KBr, BaCl 2 , MgCl 2 , Na 2 SO 4 , HCOONa) are then used to adjust neural network parameters. The developed method is then used to predict independent data (not used in training and developing of the method).…”

Thermodynamic inhibition of 4-methylmorpholine while forming sH hydrate with methane

“…Recently, the gas hydrate has become one of the major issues in flow assurance, as it may block flowlines during the production and transportation of petroleum fluids (Sloan, 2005). To deal with this severe problem, some hydrate research has focused on identifying stable regions for safe production, and searching for hydrate inhibitors that shift the equilibrium phase boundary of gas hydrates into the inhibited region so that the operational conditions can reside outside the hydrate formation region (Gbaruko et al, 2007;Ostergaard et al, 2005).…”