Application of Thermodynamic Models to Hydrate Formation Prediction during Surface Production Well Testing Using the Ratio Factor Method [ READ ]
Green, I. S., Jimmy, D. E. and Wami, E. N.
Hydrate formation, one of the problems encountered during surface production well testing, is governed by many factors including, the kinetics and thermodynamics of the system. In this paper, a thermodynamic model which centres on changes in the Langmuir constant of the guest molecule(s) under operating field conditions as crucial parameter in hydrate formation process is presented. Acquired surface production well testing data (pressure, temperature and choke size) from a hydrate well using a real time data acquisition system were used to determine the effect of choke size variation on Langmuir constant and thus on hydrate formation. A generalized correlation for evaluating Langmuir constant for large cage/cavity under field conditions was developed and expanded to incorporate variations on the choke sizes. The developed model shows that as the choke size increases, Langmuir constant decreases leading to decrease in the rate of hydrate formation. Since the driving force for hydrate formation is the product of fugacity and Langmuir constant, it then follows that as Langmuir constant approaches zero due to increasing choke size, this product also approaches zero thereby leading to zero hydrate formation.
Green, I. S., Jimmy, D. E. and Wami, E. N.
Hydrate formation, one of the problems encountered during surface production well testing, is governed by many factors including, the kinetics and thermodynamics of the system. In this paper, a thermodynamic model which centres on changes in the Langmuir constant of the guest molecule(s) under operating field conditions as crucial parameter in hydrate formation process is presented. Acquired surface production well testing data (pressure, temperature and choke size) from a hydrate well using a real time data acquisition system were used to determine the effect of choke size variation on Langmuir constant and thus on hydrate formation. A generalized correlation for evaluating Langmuir constant for large cage/cavity under field conditions was developed and expanded to incorporate variations on the choke sizes. The developed model shows that as the choke size increases, Langmuir constant decreases leading to decrease in the rate of hydrate formation. Since the driving force for hydrate formation is the product of fugacity and Langmuir constant, it then follows that as Langmuir constant approaches zero due to increasing choke size, this product also approaches zero thereby leading to zero hydrate formation.
