TOUGHREACT—A simulation program for non-isothermal multiphase reactive geochemical transport in variably saturated geologic media: Applications to geothermal injectivity and CO2 geological sequestration

Xu, Tianfu; Sonnenthal, Eric; Spycher, Nicolas; Pruess, Karsten

doi:10.1016/j.cageo.2005.06.014

Cited by 584 publications

(245 citation statements)

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“…The present studies utilize an equation of state package called ECO2N (Pruess and Spycher 2007;Spycher and Pruess 2005), designed to treat a two-phase (liquid, gas), three-component (water, salt (NaCl), CO 2 ) system in pressure/temperature regimes above the critical point of CO 2 (P = 73.8 bars, T = 31 • C), and a hysteretic formulation for capillary pressure and relative permeability (Doughty 2007). Chemical reactions among CO 2 , brine, and rock minerals are not considered in TOUGH2, but a companion code, TOUGHREACT (Xu et al 2006), is available for such studies.…”

Section: Numerical Simulatormentioning

confidence: 99%

Investigation of CO2 Plume Behavior for a Large-Scale Pilot Test of Geologic Carbon Storage in a Saline Formation

2009

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The hydrodynamic behavior of carbon dioxide (CO 2 ) injected into a deep saline formation is investigated, focusing on trapping mechanisms that lead to CO 2 plume stabilization. A numerical model of the subsurface at a proposed power plant with CO 2 capture is developed to simulate a planned pilot test, in which 1,000,000 metric tons of CO 2 is injected over a 4-year period, and the subsequent evolution of the CO 2 plume for hundreds of years. Key measures are plume migration distance and the time evolution of the partitioning of CO 2 between dissolved, immobile free-phase, and mobile free-phase forms. Model results indicate that the injected CO 2 plume is effectively immobilized at 25 years. At that time, 38% of the CO 2 is in dissolved form, 59% is immobile free phase, and 3% is mobile free phase. The plume footprint is roughly elliptical, and extends much farther up-dip of the injection well than down-dip. The pressure increase extends far beyond the plume footprint, but the pressure response decreases rapidly with distance from the injection well, and decays rapidly in time once injection ceases. Sensitivity studies that were carried out to investigate the effect of poorly constrained model parameters permeability, permeability anisotropy, and residual CO 2 saturation indicate that small changes in properties can have a large impact on plume evolution, causing significant trade-offs between different trapping mechanisms.

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Section: Numerical Simulatormentioning

confidence: 99%

Investigation of CO2 Plume Behavior for a Large-Scale Pilot Test of Geologic Carbon Storage in a Saline Formation

2009

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“…The creation and compilation of thermodynamic databases, along with improved computer technology, laid the basis for this development. The databases have been used with geochemical computer codes, such as EQ3/6 (Wolery, 1983(Wolery, , 1992, WATCH (Arnórsson et al, 1982;Bjarnason, 1994), SUPCRT92 (Johnson et al, 1992), PHREEQC (Parkhurst et al, 1980;Parkhurst and Appelo, 1999) and TOUGHREACT (Xu et al, 2006(Xu et al, , 2011, allowing for rapid simulations of mineral solubility and solute speciation in a variety of geochemical systems. The codes differ in complexity and ease of use, but all accurately solve for the equilibrium assemblages of minerals and aqueous species, and mineral solubilities within the limits of their thermodynamic databases.…”

Section: Introductionmentioning

confidence: 99%

Development and evaluation of a thermodynamic dataset for phases of interest in CO2 mineral sequestration in basaltic rocks

2012

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Keywords: Thermodynamic dataset CO 2 -waterbasalt interaction Geochemical modeling CO 2 geological storage In situ CO 2 mineral sequestration A B S T R A C T A thermodynamic dataset describing 36 mineral reactions of interest for CO 2 -water-basalt interaction associated with CO 2 mineral sequestration in basaltic formations is presented. Mineral selection for the dataset is based on extensive review of natural analogs of water-basalt interaction at low and elevated CO 2 conditions. Widely used thermodynamic databases did not contain the mineral assemblage needed for successfully simulating the alteration processes observed in nature as important primary and secondary minerals were found to be missing. The EQ3/6 V7.2b database is the primary source for aqueous equilibrium constants in the developed dataset but reactions for four missing Al-hydroxy complexes were added. Recently published thermodynamic data were compiled for most of the minerals considered in this study. Mineral solubility constants obtained directly from measurements were compiled to the dataset without modification but SUPCRT was used for computing solubility constants when such data was not available. In order to verify that the presented dataset can capture alterations observed in nature, simulations of CO 2 -water-basalt interaction were carried out at low and elevated CO 2 conditions and compared to observed basalt alteration in Iceland and Greenland. Overall simulated and observed alteration are in good agreement, both at low and elevated CO 2 conditions, suggesting the dataset to be well suited for simulations of e.g. CO 2 -water-basalt interaction associated with CO 2 mineral sequestration in basalts.

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“…For more details, the reader can consult the TOUGHREACT User's Guide (Xu et al, 2004a) and Xu et al (2006), as well as the different FRACHEM studies on the Soultz system (Durst, 2002, Bächler et al, 2005.…”

Section: -3mentioning

confidence: 99%

“…The reactive transport simulator developed at LBNL, TOUGHREACT Xu et al, , 2004aXu et al, , 2004bXu et al, , and 2006 was based on introducing reactive chemistry into the code TOUGH2 (Pruess 1991). TOUGHREACT has been applied to different problems, such as CO 2 sequestration in deep saline aquifers and the evolution of water-rock interactions around nuclear 1-2 waste disposal sites.…”

Section: Introductionmentioning

confidence: 99%

Modeling brine-rock interactions in an enhanced geothermal systemdeep fractured reservoir at Soultz-Sous-Forets (France): a joint approachusing two geochemical codes: frachem and toughreact

André¹,

Spycher²,

Xu³

et al. 2006

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EXECUTIVE SUMMARYThe modeling of coupled thermal, hydrological, and chemical (THC) processes in geothermal systems is complicated by reservoir conditions such as high temperatures, elevated pressures and sometimes the high salinity of the formation fluid. Coupled THC models have been developed and applied to the study of enhanced geothermal systems (EGS) to forecast the long-term evolution of reservoir properties and to determine how fluid circulation within a fractured reservoir can modify its rock properties. In this study, two simulators, FRACHEM and TOUGHREACT, specifically developed to investigate EGS, were applied to model the same geothermal reservoir and to forecast reservoir evolution using their respective thermodynamic and kinetic input data. First, we report the specifics of each of these two codes regarding the calculation of activity coefficients, equilibrium constants and mineral reaction rates. Comparisons of simulation results are then made for a Soultz-type geothermal fluid (ionic strength ~1.8 molal), with a recent (unreleased) version of TOUGHREACT using either an extended Debye-Hückel or Pitzer model for calculating activity coefficients, and FRACHEM using the Pitzer model as well.Despite somewhat different calculation approaches and methodologies, we observe a reasonably good agreement for most of the investigated factors. Differences in the calculation schemes typically produce less difference in model outputs than differences in input thermodynamic and kinetic data, with model results being particularly sensitive to differences in ion-interaction parameters for activity coefficient models. Differences in input thermodynamic equilibrium constants, activity coefficients, and kinetics data yield differences in calculated pH and in predicted mineral precipitation behavior and reservoir-porosity evolution. When numerically cooling a Soultz-type geothermal fluid from 200°C (initially equilibrated with calcite at pH 4.9) to 20°C and suppressing mineral precipitation, pH values calculated with FRACHEM and TOUGHREACT/ Debye-Hückel decrease by up to half a pH unit, whereas pH values calculated with TOUGHREACT/Pitzer increase by a similar amount. As a result of these differences, calcite solubilities computed using the Pitzer formalism (the more accurate approach) are up to about 1.5 orders of magnitude lower. Because of differences in Pitzer ion-interaction parameters, the calcite solubility computed with TOUGHREACT/Pitzer is also typically about 0.5 orders of magnitude lower than that computed with FRACHEM, with the latter expected to be most accurate.In a second part of this investigation, both models were applied to model the evolution of a Soultz-type geothermal reservoir under high pressure and temperature conditions. By specifying initial conditions reflecting a reservoir fluid saturated with respect to calcite (a reasonable assumption based on field data), we found that THC reservoir simulations with the three models yield similar results, including similar trends and amounts of reservoir po...

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TOUGHREACT—A simulation program for non-isothermal multiphase reactive geochemical transport in variably saturated geologic media: Applications to geothermal injectivity and CO2 geological sequestration

Cited by 584 publications

References 43 publications

Investigation of CO2 Plume Behavior for a Large-Scale Pilot Test of Geologic Carbon Storage in a Saline Formation

Investigation of CO2 Plume Behavior for a Large-Scale Pilot Test of Geologic Carbon Storage in a Saline Formation

Development and evaluation of a thermodynamic dataset for phases of interest in CO2 mineral sequestration in basaltic rocks

Modeling brine-rock interactions in an enhanced geothermal systemdeep fractured reservoir at Soultz-Sous-Forets (France): a joint approachusing two geochemical codes: frachem and toughreact

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