Measurements and Predictions of Hydrate Equilibrium Conditions

Abstract

The main objective of this study was to demonstrate the importance of reliable hydrate equilibrium data for thorough mitigation and remediation of hydrate problems. Hydrate prevention strategies generally rely on extensive use of different hydrate simulators that, in turn, are based on experimental data. Erroneous hydrate predictions may severely jeopardize the established hydrate strategy and can have severe economic implications. In this study the hydrate equilibrium conditions for eight different hydrocarbon systems were investigated by experimental measurements and by hydrate simulator predictions. The results clearly verify the importance of having due control over the experimental parameters, especially the heating gradient. The error in the determination of the hydrate equilibrium temperature seems to increase with the complexity of the system; for example, when inhibitors are added to the aqueous phase.

Some aspects of hydrate formation and wetting

“…Details of the experimental setup have been described elsewhere [19]. The main part of the setup is a cylindrical cell fitted with a sapphire section and a movable piston.…”

Reliability and Performance of Vinyl Lactam-Based Kinetic Hydrate Inhibitor Polymers after Treatment under a Range of Conditions

“…Temperatures in the cells and the water bath were observed to be homogeneous. The two methods that we used to determine the hydrate equilibrium temperature (HET) for high-pressure gas hydrate systems are calculations using Calsep’s PVTSim and laboratory experiments by standard slow hydrate dissociation. , Previous experiments conducted by our group using a SNG–water system agreed very well with the calculated value (accuracy within 1 °C) …”

Acylamide and Amine Oxide Derivatives of Linear and Hyperbranched Polyethylenimine. Part 2: Comparison of Gas Kinetic Hydrate Inhibition Performance

“…The gas composition used was a synthetic natural gas mixture given in Table 1. The equilibrium temperature (T eq ) at the initial pressure of 76 bar was determined to be 20.2 o C ±0.05 o C by standard laboratory dissociation experiments warming at 0.025 o C/h for the last 3-4 o C. [28][29] This value agrees very well with a calculated T eq value of 20.5 o C at 76 bar using Calsep's PVTSim software. The KHI test procedure was a constant cooling test method over 18.5 hours.…”