Instrumental analysis of gas hydrates properties

Abstract

Gas hydrates attracted intense research interest when it was first recognised some 70 years ago that they were responsible for the blockage of flow lines, valves and well heads, thereby causing great loss of production and other severe safety hazards to the oil and gas industry. After many decades, these compounds are still the topic of research activities in various multi-disciplinary fields, including chemical and petroleum engineering, earth and geophysics, chemistry and environmental sciences. This is not only due to the great impact that these compounds have on the oil and gas industry, but also to the potential applications they have in many evolving areas, including, but not only, natural gas storage and transportation, carbon dioxide sequestration, and sea-water desalination. It is generally accepted that gas hydrates represent the largest source of hydrocarbons on earth, something which has not been appreciated until only recently.Management, either prevention or application or both, of gas hydrates requires a complete knowledge and understanding of the formation, decomposition and inhibition mechanisms of gas hydrates, which in turn demands advanced experimental methods and instrumental techniques for gas hydrate characterisation. This paper reviews a broad range of techniques that have been used for natural gas hydrate characterisation. It includes the basic physical science principles of each method and the gas hydrate properties that each method is capable of detecting, including some modern instrumental analyses that enable direct determination of gas hydrate phases and possible measurement of molecular interactions within the fluid phases. 

Hydration Behavior of Polylactam Clathrate Hydrate Inhibitors and Their Small-Molecule Model Compounds

“…[11][12][13] There have been several recent developments in this area which are reliant on characterization of the resulting gas hydrate phases. In particular, high-pressure powder X-ray diffraction, 14 NMR spectroscopy and high-pressure calorimetry 15 , have been used to probe inhibition using chemical KHIs or anti-freeze proteins.…”

Hydration Behavior of Polylactam Clathrate Hydrate Inhibitors and theirSmall‐MoleculeModel Compounds

“…A plethora of techniques are used in order to gain insight into gas hydrate nucleation and growth, and the potential mode of action of KHIs on the macroscopic and microscopic scale. [11][12][13] There have been several recent developments in this area which are reliant on characterization of the resulting gas hydrate phases. In particular, high-pressure powder X-ray diffraction, 14 NMR spectroscopy and high-pressure calorimetry 15 , have been used to probe inhibition using chemical KHIs or anti-freeze proteins.…”

The Relationship between Thermal Characteristics and Microstructure/Composition of Carbon Dioxide Hydrate in the Presence of Cyclopentane

“…The hydrate formation or/and decomposition enthalpy is closely related to the hydrate structure and composition. And the hydrate structure and composition could be determined by many micro analytical methods, e.g., Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Powder X-ray Diffraction (PXRD), Nuclear Magnetic Resonance (NMR) [47][48][49]. For instance, Chen et al [50] investigated structures of CO 2 hydrate and THF + CO 2 binary hydrate by Raman spectra, and they found in the pure CO 2 hydrate, CO 2 molecules occupy both medium 5 12 6 2 and small 5 12 cages, while CO 2 molecules only occupy the small 5 12 cages in the binary hydrate.…”