Thermodynamic properties of acid gases in mixture with natural gas and water

Abstract

The reliable removal of acid gas components, such as carbon dioxide (CO2) and hydrogen sulfide (H2S) from natural gas is an important technical challenge. Crude oil and hydrocarbon gas streams may contain high levels of CO2 and/or H2S as contaminants. It is desirable to prevent any contaminant to reach the surface, or to considerably reduce the contaminant levels reaching surface facilities. Opportunities for the disposal of the unwanted components include subsurface sequestration of the substances. This book analyses the underlying thermodynamic properties of the involved mixtures and proposes a modeling formalism. The first Chapter gives background to the project, introduces the molecular methods that are applied in later chapters, and identifies scientific needs that are addressed with this book. Chapter 2 proposes a physically sound model for the phase equilibrium of CO2 and H2S with hydrocarbons and water. Chapter 3 proposes a model for an adequate description of the critical region (as well as conditions away from the critical point) using renormalization group corrections. Chapter 4 proposes a model for the calculation of the surface tension including the critical region. Chapter 5 proposes a simple, pragmatic model for the solubility of CO2 in K2CO3 aqueous solutions. This study provides models for the physical properties of natural gas and crude oil mixtures, needed for a reliable calculation of separation systems. An adequate model for electrolytes which is needed for an improved modeling of a membrane contactor remains to be developed.