Methane-rich fluids

Clifford 2000). Many metallic ore and evaporite minerals contain methane, though not in hydrate form. For instance, the Red Dog zinc ores mentioned above contain methane inclusions in association with saline inclusions. In many instances, microscopic methane and carbon-dioxide-rich fluid inclusions form clathrates within their tiny hydrous envelopes. Some salt deposits are so enriched in high-pressure free gas inclusions and/or gas hydrates that mining, crushing under boot, or other means of physical disturbance causes popping or even explosive decrepitation. 

Figure 3A.1 requires explanation. At 4.137 MPa, the two-phase region is a trapezoid. The trapezoid extends from binary VLE between COz and HjS to binary VLE between H2S and CH4. To the left of this trapezoid, the fluid is a vapor. These fluids would be rich in methane. To the right of the trapezoid the mixture is a liquid. 

A methane and ethylene rich gas as well as a condensable liquid part with a high percentage of aromatics are produced (see Table II), The main part of the filler materials - carbon soot and zincoxide - is blown out of the fluid bed and can be separated in a cyclone. The carbon soot is dry and trickles out of the cyclone. 

In order to obtain a direct and more accurate pressure determination, various internal pressure calibrants (e.g. quartz and ruby chips) are generally used. Internal calibrants, however, could not be used in the high temperature hydrothermal experiments due to interactions with the chemical system. In such cases, one of the more prevalent phases of the chemical system was calibrated as pressure indicator. For fluid-rich systems (methane-water), the pressures were also determined using the known phase equilibria of the methane hydrate decomposition and using shifts in the ruby fluorescence peak [8]. 

The constants A, B, C, a, b, c, a and P are characteristic for a given fluid. BWR-EOS and its recent modifications permit accurate calculations of physical properties of light gases, non-polar or slightly polar components medium pressure. BWR-EOS can be used for both thermodynamic properties, as enthalpy and entropy, and phase equilibrium. It is also suited for light hydrocarbon processes, including rich methane and hydrogen mixtures, as well as in gas liquefaction. 

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