Book•
Clathrate hydrates of natural gases
01 Jan 1990-
TL;DR: In this paper, the authors compared the properties of hydrates and ice with those of natural gas and showed the effect of thermodynamic inhibitors on the formation of hydrate formation and dissolution process.
Abstract: PREFACE Overview and Historical Perspective Hydrates as a Laboratory Curiosity Hydrates in the Natural Gas Industry Hydrates as an Energy Resource Environmental Aspects of Hydrates Safety Aspects of Hydrates Relationship of This Chapter to Those That Follow Molecular Structures and Similarities to Ice Crystal Structures of Ice Ih and Natural Gas Hydrates Comparison of Properties of Hydrates and Ice The What and the How of Hydrate Structures Hydrate Formation and Dissociation Processes Hydrate Nucleation Hydrate Growth Hydrate Dissociation Estimation Techniques for Phase Equilibria of Natural Gas Hydrates Hydrate Phase Diagrams for Water + Hydrocarbon Systems Three-Phase (LW-H-V) Equilibrium Calculations Quadruple Points and Equilibrium of Three Condensed Phases (LW-H-LHC) Effect of Thermodynamic Inhibitors on Hydrate Formation Two-Phase Equilibrium: Hydrates with One Other Phase Hydrate Enthalpy and Hydration Number from Phase Equilibrium Summary and Relationship to Chapters Which Follow A Statistical Thermodynamic Approach to Hydrate Phase Equilibria Statistical Thermodynamics of Hydrate Equilibria Application of the Method to Analyze Systems of Methane + Ethane + Propane Computer Simulation: Another Microscopic-Macroscopic Bridge Summary Experimental Methods and Measurements of Hydrate Properties Experimental Apparatuses and Methods for Macroscopic Measurements Measurements of the Hydrate Phase Data for Natural Gas Hydrate Phase Equilibria and Thermal Properties Summary and Relationship to Chapters that Follow References Hydrates in the Earth The Paradigm Is Changing from Assessment of Amount to Production of Gas Sediments with Hydrates Typically Have Low Contents of Biogenic Methane Sediment Lithology and Fluid Flow Are Major Controls on Hydrate Deposition Remote Methods Enable an Estimation of the Extent of a Hydrated Reservoir Drilling Logs and/or Coring Provide Improved Assessments of Hydrated Gas Amounts Hydrate Reservoir Models Indicate Key Variables for Methane Production Future Hydrated Gas Production Trends Are from the Permafrost to the Ocean Hydrates Play a Part in Climate Change and Geohazards Summary Hydrates in Production, Processing, and Transportation How Do Hydrate Plugs Form in Industrial Equipment? How Are Hydrate Plug Formations Prevented? How Is a Hydrate Plug Dissociated? Safety and Hydrate Plug Removal Applications to Gas Transport and Storage Summary of Hydrates in Flow Assurance and Transportation APPENDICES INDEX
Citations
More filters
TL;DR: Natural gas hydrates have an important bearing on flow assurance and safety issues in oil and gas pipelines, they offer a largely unexploited means of energy recovery and transportation, and could play a significant role in past and future climate change.
Abstract: Natural gas hydrates are solid, non-stoichiometric compounds of small gas molecules and water. They form when the constituents come into contact at low temperature and high pressure. The physical properties of these compounds, most notably that they are non-flowing crystalline solids that are denser than typical fluid hydrocarbons and that the gas molecules they contain are effectively compressed, give rise to numerous applications in the broad areas of energy and climate effects. In particular, they have an important bearing on flow assurance and safety issues in oil and gas pipelines, they offer a largely unexploited means of energy recovery and transportation, and they could play a significant role in past and future climate change.
2,419 citations
TL;DR: The recent confirmation that there is at least one world rich in organic molecules on which rivers and perhaps shallow seas or bogs are filled with nonaqueous fluidsthe liquid hydrocarbons of Titan now bring some focus, even urgency, to the question of whether water is indeed a matrix of life.
Abstract: When Szent-Gyorgyi called water the “matrix of life”,1 he was echoing an old sentiment. Paracelsus in the 16th century said that “water was the matrix of the world and of all its creatures.”2 But Paracelsus’s notion of a matrixsan active substance imbued with fecund, life-giving propertiess was quite different from the picture that, until very recently, molecular biologists have tended to hold of water’s role in the chemistry of life. Although acknowledging that liquid water has some unusual and important physical and chemical propertiessits potency as a solvent, its ability to form hydrogen bonds, its amphoteric naturesbiologists have regarded it essentially as the backdrop on which life’s molecular components are arrayed. It used to be common practice, for example, to perform computer simulations of biomolecules in a vacuum. Partly this was because the computational intensity of simulating a polypeptide chain was challenging even without accounting for solvent molecules too, but it also reflected the prevailing notion that water does little more than temper or moderate the basic physicochemical interactions responsible for molecular biology. What Gerstein and Levitt said 9 years ago remains true today: “When scientists publish models of biological molecules in journals, they usually draw their models in bright colors and place them against a plain, black background”.3 Curiously, this neglect of water as an active component of the cell went hand in hand with the assumption that life could not exist without it. That was basically an empirical conclusion derived from our experience of life on Earth: environments without liquid water cannot sustain life, and special strategies are needed to cope with situations in which, because of extremes of either heat or cold, the liquid is scarce.4-6 The recent confirmation that there is at least one world rich in organic molecules on which rivers and perhaps shallow seas or bogs are filled with nonaqueous fluidsthe liquid hydrocarbons of Titan7smight now bring some focus, even urgency, to the question of whether water is indeed a * E-mail: p.ball@nature.com. Philip Ball is a science writer and a consultant editor for Nature, where he worked as an editor for physical sciences for more than 10 years. He holds a Ph.D. in physics from the University of Bristol, where he worked on the statistical mechanics of phase transitions in the liquid state. His book H2O: A Biography of Water (Weidenfeld & Nicolson, 1999) was a survey of the current state of knowledge about the behavior of water in situations ranging from planetary geomorphology to cell biology. He frequently writes about aspects of water science for both the popular and the technical media.
1,798 citations
TL;DR: It is shown that thermodynamic and kinetic constraints largely prevent large-scale methanogenesis in the open ocean water column, and the role of anaerobic oxidation of methane has changed from a controversial curiosity to a major sink in anoxic basins and sediments.
Abstract: This review shows that thermodynamic and kinetic constraints largely prevent large-scale methanogenesis in the open ocean water column. One example of open-ocean methanogenesis involves anoxic digestive tracts and fecal pellet microenvironments; methane released during fecal pellet disaggregation results in the mixed-layer methane maximum. However, the bulk of the methane in the ocean is added by coastal runoff, seeps, hydrothermal vents, decomposing hydrates, and mud volcanoes. Since methane is present in the open ocean at nanomolar concentrations, and since the flux to the atmosphere is small, the ultimate fate of ocean methane additions must be oxidation within the ocean. As indicated in the Introduction and highlighted in Table 3, sources of methane to the ocean water column are poorly quantified. There are only a small number of direct water column methane oxidation rates, so sinks are also poorly quantified. We know that methane oxidation rates are sensitive to ambient methane concentrations, but we have no information on reaction kinetics and only one report of the effect of pressure on methane oxidation. Our perspective on methane sources and the extent of methane oxidation has been changed dramatically by new techniques involving gene probes, determination of isotopically depleted biomarkers, and recent 14C-CH4 measurements showing that methane geochemistry in anoxic basins is dominated by seeps providing fossil methane. The role of anaerobic oxidation of methane has changed from a controversial curiosity to a major sink in anoxic basins and sediments. © 2007 American Chemical Society.
1,194 citations
TL;DR: The exploration of structural and binding properties of small water complexes provides a key for understanding bulk water in its liquid and solid phase and for understanding solvation phenomena.
Abstract: Water is of fundamental importance for human life and plays an important role in many biological and chemical systems. Although water is the most abundant compound on earth, it is definitely not a simple liquid. It possesses strongly polar hydrogen bonds which are responsible for a striking set of anomalous physical and chemical properties. For more than a century the combined importance and peculiarity of water inspired scientists to construct conceptual models, which in themselves reproduce the observed behavior of the liquid. The exploration of structural and binding properties of small water complexes provides a key for understanding bulk water in its liquid and solid phase and for understanding solvation phenomena. Modern ab initio quantum chemistry methods and high-resolution spectroscopy methods have been extremely successful in describing such structures. Cluster models for liquid water try to mimic the transition from these clusters to bulk water. The important question is: What cluster properties are required to describe liquid-phase behavior?
1,116 citations
TL;DR: The primary adsorption sites for Ar and N2 within metal-organic framework-5, a cubic structure composed of Zn4O(CO2)6 units and phenylene links defining large pores 12 and 15 angstroms in diameter, have been identified by single-crystal x-ray diffraction.
Abstract: The primary adsorption sites for Ar and N2 within metal-organic framework-5, a cubic structure composed of Zn4O(CO2)6 units and phenylene links defining large pores 12 and 15 angstroms in diameter, have been identified by single-crystal x-ray diffraction. Refinement of data collected between 293 and 30 kelvin revealed a total of eight symmetry-independent adsorption sites. Five of these are sites on the zinc oxide unit and the organic link; the remaining three sites form a second layer in the pores. The structural integrity and high symmetry of the framework are retained throughout, with negligible changes resulting from gas adsorption.
817 citations