Lars Henrik Gjertsen

Hydrate Plug Properties: Formation and Removal of Plugs

Abstract: The properties of hydrate plugs have been demonstrated to vary from case to case. Plugs formed in a gas/HC liquid/water system consist of hydrate particles and pores with gas and liquid constituting both water and HC at different portions. The composition of the gas and liquids trapped in the pores plays a major role in the probability of plugging as well as the behavior of plugs during melting.

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.

Thermodynamic Inhibitors for Hydrate Plug Melting

Abstract: The hydrate melting efficiency of thermodynamic inhibitors has been shown to depend on hydrate plug properties, inhibitor properties, and the turbulence of the liquid system in question. Inefficient mixing of inhibitor and water, lack of contact between inhibitor and hydrate, and a solid or gel precipitation in the melting region have been demonstrated to give low melting efficiency. MeOH seems to be the most efficient inhibitor for melting porous plugs, but may not melt a plug with low porosity. MEG has the ability to penetrate into a compact plug and cause melting. However, when used at high concentrations, MEG may freeze out as a solid or gel, which can lead to reduced hydrate melting efficiency. At high pressures and in the presence of a hydrocarbon liquid, MEG solutions were shown to freeze out at temperatures more than 30°C higher than values given in the literature. TEG seems to easily freeze and become inefficient for melting hydrate plugs.

Chemical Influence on the Formation, Agglomeration, and Natural Transportability of Gas Hydrates. A Multivariate Component Analysis

Abstract This study has focused on chemical components in two paraffinic oil phases, expected to have an influence on the properties of gas hydrates regarding formation, agglomeration, and natural transportability. Crude oil, toluene, wax, and naphtenic acids were selected for this purpose. Two paraffinic phases were used; n‐decane and Exxsol D‐80, the latter containing surface active material. The experiments were performed in a sapphire PVT‐cell. The use of experimental design and multivariate data analysis facilitates identification of the important chemical components. Interfacial tension measurements towards de‐ionised water were performed on the paraffinic solutions to gain more information on the interfacial phenomena.