The prediction of methane solubility in natural waters to high ionic strength from 0 to 250°C and from 0 to 1600 bar

Duan, Zhenhao; Møller, Nancy; Greenberg, Joshua I.; Weare, John H.

doi:10.1016/0016-7037(92)90215-5

Cited by 358 publications

(261 citation statements)

References 21 publications

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“…More accurate equations-of- Duan et al [1992a], with the equation of state for methane that of Duan et al [1992b]. The solubility curve, shown in Figure 4 for Svalbard, quantifies the boundary condition of dissolved-gas concentration at the base of the GHSZ and also quantifies the concentration in all parts of the system coexisting with free gas.…”

Section: Free-gas Concentrationmentioning

confidence: 99%

Controls on the formation and stability of gas hydrate‐related bottom‐simulating reflectors (BSRs): A case study from the west Svalbard continental slope

2008

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[1] The growth and stability of the free-gas zone (FGZ) beneath gas-hydrate related bottom-simulating seismic reflectors (BSRs) is investigated using analytical and numerical analyses to understand the factors controlling the formation and depletion of free gas. For a model based on the continental slope west of Svalbard (a continental margin of north Atlantic type), we find that the FGZ is inherently unstable under a wide range of conditions because upward flow of under-saturated liquid depletes free gas faster than it is produced by hydrate recycling. In these scenarios, the 150-m-thick FGZ that presently exists there would deplete within 10 5 -10 6 years. We suggest the FGZ is in a stable state, however, that is formed by a diffusion-dominated mechanism that produces low concentrations of gas in a FGZ of steady state thickness. Gas forms across a thick zone because the upward fluid flux is relatively low and because the gas-water solubility decreases to a minimum several hundred meters below the seabed. This newly understood solubility-curvature effect is complementary to hydrate recycling, but becomes the most important factor controlling the presence and properties of the BSR in environments where the rate of upward fluid flow and the rate of hydrate recycling are both relatively low (i.e., rifted continental margins). If the present-day FGZ is in steady state, we estimate that the upward fluid flux in the west Svalbard site must be less than 0.15 mm a À1 .Citation: Haacke, R. R., G. K. Westbrook, and M. S. Riley (2008), Controls on the formation and stability of gas hydrate-related bottom-simulating reflectors (BSRs): A case study from the west Svalbard continental slope,

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Section: Free-gas Concentrationmentioning

confidence: 99%

Controls on the formation and stability of gas hydrate‐related bottom‐simulating reflectors (BSRs): A case study from the west Svalbard continental slope

2008

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“…The measured methane concentration in this sample is 20 gM (Table 3), although this concentration represents a minimum because gas was lost as the sample was processed. The measured value is lower than methane solubility in seawater at 30øC and 1 bar pressure (-•1 mM) [Duan et al, 1992], however, and thus should be close to the in situ concentration. Considering a limiting situation where 97% of the original methane has been oxidized in order to change its isotopic composition from -7796o (a microbial source) to the measured value of-30.696o (Figure 7 …”

Section: Rov Observations and Sedimentary Petrographymentioning

confidence: 47%

Chemical and isotopic evidence of gas‐influenced flow at a transform plate boundary: Monterey Bay, California

Martin¹,

Orange²,

Lorenson³

et al. 1997

J. Geophys. Res.

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“…Previously, we constructed a model for predicting methane solubility in multicomponent geothermal brines (0 -6 m) from 0° to 250°C and from 0 to1600 bar (see Table 4, Duan et al, 1992c). This model incorporates Pitzer specific interaction phenomenology, parameterized by solubility data, to describe the liquid phase.…”

Section: Results/variances: Tequil Modelsmentioning

confidence: 99%

Models of Geothermal Brine Chemistry

Weare¹,

Weare²

2002

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PROJECT BACKGROUND: Many significant expenses encountered by the geothermal energy industry are related to chemical effects. When the composition, temperature or pressure of the fluids in the geological formation are changed, during reservoir evolution, well production, energy extraction or injection processes, the fluids that were originally at equilibrium with the formation minerals come to a new equilibrium composition, temperature and pressure. As a result, solid material can be precipitated, dissolved gases released and/or heat lost. Most geothermal energy operations experience these phenomena. For some resources, they create only minor problems. For others, they can have serious results, such as major scaling or corrosion of wells and plant equipment, reservoir permeability losses and toxic gas emission, that can significantly increase the costs of energy production and sometimes lead to site abandonment. In future operations that exploit deep heat sources and low permeability reservoirs, new chemical problems involving very high T, P rock/water interactions and unknown injection effects will arise.The ability to predict chemical behavior and heat content for wide ranges of composition, temperature and pressure would enable the design of optimal operating strategies to minimize or avoid these adverse chemical effects. Predicting reservoir and energy production chemistry will become even more important as deeper, higher temperature geothermal resources, with very high development costs, are utilized to meet future energy needs. Unfortunately, predicting the chemistry of geothermal systems is difficult because of the variability and complexity of the solidliquid-gas equilibria controlling chemical behavior. These equilibria are complicated functions of the system's composition, temperature and pressure (XTP). These variables are different for different resources and can vary over time and from well to well in a single resource. Marked changes in XTP variables also occur during energy extraction from a specific site. Reliance on experimental data for estimating behavior is generally inadequate because the data pertain to a given set of variables and are often for relatively low temperature (˜100°C) and pressure (≈1 bar). The chemical complexity of geothermal systems makes the extrapolation of data to different conditions problematic. New laboratory simulations are time-consuming and costly, particularly at high temperature and pressure. Moreover, the very high temperatures and pressures of deep crustal and magma resources, where the bulk of the earth's heat is stored, are difficult or impossible to duplicate by current experimental methods.Computer modeling technologies present the means to resolve these difficulties. Wellconstructed models, based on sound thermodynamic principles, can handle the complicated chemical reactions determining the behavior of geothermal energy production processes. They provide a means of succinctly summarizing large amounts of experimental data and of With support from the DOE Ge...

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The prediction of methane solubility in natural waters to high ionic strength from 0 to 250°C and from 0 to 1600 bar

Cited by 358 publications

References 21 publications

Controls on the formation and stability of gas hydrate‐related bottom‐simulating reflectors (BSRs): A case study from the west Svalbard continental slope

Controls on the formation and stability of gas hydrate‐related bottom‐simulating reflectors (BSRs): A case study from the west Svalbard continental slope

Chemical and isotopic evidence of gas‐influenced flow at a transform plate boundary: Monterey Bay, California

Models of Geothermal Brine Chemistry

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