Solubility methane

Triaminotriphenyl methane soluble dyes, 7 373t Triammonium phosphate, 18 835 Triamterene, 5.T68... 

Triphenyl methane soluble dyes, 7 373t Triphenylmethane dyes, 72 50 Triphenyl methane phenols soluble dyes, 7 373t Triphenylmethylcesium, 5 694 Triphenylphosfonium iodide, 74 370 Triphenyl phosphate, 77 485, 494 Triphenylphosphine, 79 60, 61, 70 363, 20 300... 

Hert, D. G. et al. Enhancement of oxygen and methane solubility in l-hexyl-3-methyl imidazolium bis(trifluoromethylsulfonyl) imide using carbon dioxide, Chem. Commun., 2603, 2005. 

Figure 3.27 Methane hydrate film development at the water-methane interface from dissolved methane in the aqueous phase, as indicated from Raman spectroscopy (a) and methane solubility predictions (b). (a) A series of Raman spectra of dissolved methane collected at different temperatures during the continuous cooling process. Spectra marked A through E correspond to temperatures of 24°C, 20°C, 15.6°C, 10.2°C, and 2.8°C, respectively. (b) A schematic illustration of temperature dependencies of the equilibrium methane concentration in liquid water (C = without hydrate, Qjh = with hydrate). The scale of the vertical axis is arbitrary, but the Raman peak area is proportional to methane dissolved in water. Points A through F correspond to different temperatures during the continuous cooling process. (From Subramanian, S., Measurements ofClathrate Hydrates Containing Methane and Ethane Using Raman Spectroscopy, Ph.D. Thesis, Colorado School of Mines, Golden, CO (2000). With permission.)...

There are only few data sets of aqueous solubility for systems with hydrates (1) methane and ethane solubility in water as a function of temperature ramping rate (Song et al. 1997), (2) carbon dioxide solubility in water by Yamane and Aya (1995), (3) methane in water and in seawater (Besnard et al., 1997), (4) methane in water in Lw-H region [see Servio and Englezos (2002) and Chou and Burruss, Personal Communication, December 18,2006, Chapter 6], As a standard for comparison, Handa s (1990) calculations for aqueous methane solubility are reported in Table 4.3. 

Calculations of Methane Solubility in Water and Seawater, at Conditions Above and Below the Hydrate Point... 

Hydrate formation by in-place biogenic methane Kvenvolden and Barnard (1983) and Brooks et al. (1985) followed the Claypool and Kaplan (1974) suggestion that free methane can be generated in place using the diagenetic mechanism indicated above. Brooks et al. (1987) indicate that twice the methane solubility amount can be achieved by in situ production. 

Methane Solubility Further Limits the Hydrate Occurrence... 

Figure 7.13 Methane solubility imposes a narrower limit than the P-T stability region for hydrate depth.

As shown in Figure 7.13 the pressure and temperature limits to the hydrate stability exists from the seafloor (because hydrates are less dense than seawater) to the intersection of the geotherm (BGHS). The solubility limit, however, imposes a further depth restriction because the methane concentration must equal the solubility limit to be in equilibrium with hydrates. It is assumed that the sediment provides sufficient nucleation sites so that there is no methane metastability, so hydrate forms in the narrow depth region where methane concentration lies atop the methane solubility line. As illustrated in the Leg 311 case study, the GHOZ is always smaller than the GHSZ. 

Below the SMI to a submudline level ten times the depth of the SMI, hydrates are not found because the methane concentration is too low to produce hydrates. It should be noted that this Rule of 10 is perhaps related to methane solubility limit in the liquid phase. Even though the deeper hydrate layers have a lesser concentration, due to the larger volume, the deeper hydrate amounts represent the largest in the reservoir, and cause the total reservoir concentration to be estimated at 2.5% of pore volume. 

Table 7.12 compares the hydrate amounts (as percent of pore space) estimated by the above three techniques, to that from the RAB for the GHOZ and GHSZ. Below the surflcial hydrates mentioned earlier, for a few tens of meters below the mudline, the methane concentration is not sufficient for hydrate formation. One possible reason for the discrepancy in the values of GHOZ and GHSZ is Pauli s Rule of 10, which relates hydrate depth to ten times the SMI, as discussed in Section 7.2.2. As mentioned this Rule of 10 may be related to methane solubility. 

The influence of pressure on hydrocarbon solubility has been studied for methane by Bonham (1978) and Price (1976). Figure 3.9, as presented by Bonham, shows the increase of methane solubility with increasing pressure. 

Fig. 14.18 Upper panel illustrates dissolved chloride concentration in pore waters collected from the summit of Hydrate Ridge during ODP leg 204 (Sites 1249, 1250, from Torres et al. 2004) and from a gravity core recovered from this area during RV SONNE expedition SO-143 (Haeckel et al. 2004). These data (panels A-C) indicate that hydrate is forming at very fast rates, so as to maintain the extremely high chloride values. Furthermore, to sustain the rapid formation rates, Torres et al. (2004) and Haeckel et al. (2004) show that methane must be supplied in the gas phase, as illustrated by the cartoon in panel. Methane solubility in seawater is too low for aqueous transport to deliver sufficient methane to form the observed hydrate deposits. D. Mass balance calculations based on a simple box model (E) indicate that the massive deposits recovered from the Hydrate Ridge summit probably formed in a period of the order of lOO s to lOOO s of years, highlighting the dynamic nature of these near-surface deposits (modified from Torres et al. 2004 and Haeckel et al. 2004).

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