Bibliography - Jean Hervé Prévost

Gor, Gennady Y., Thomas R. Elliot, and Jean Hervé Prévost, 2012: Effects of thermal stresses on caprock integrity during CO₂ storage. International Journal of Greenhouse Gas Control, Elsevier Ltd., 12, doi:10.1016/j.ijggc.2012.11.020 300-309
[ Abstract ]
Subsurface fluid injection results in a pore pressure increase, which induces geomechanical stresses. Additionally, if there exists a difference between the ambient formation temperature and the temperature of injected fluid, thermal stresses can develop. Herein we study the effect of CO₂ injection temperature on caprock integrity using coupled thermo-poromechanical multi-phase simulations. Calculations show that when CO₂ is injected within several years at a temperature below the ambient value in the formation, the stresses above the horizontal injection well lead to tensile or shear failure of the caprock. We study the sensitivity of resulting stresses to the injection temperature, caprock density and initial in situ stresses. We also show that the caprock failure can lead to propagating fractures, which may serve as pathways for CO₂ leakage. Based on the results of our simulations we estimate the rate of fracture propagation and study the effect of caprock permeability on this rate. Our results show that injection of CO₂ at temperature close to the ambient value in the aquifer significantly reduces the risk of caprock fracturing and, therefore, of possible leakage.
Goumiri, I., Jean Hervé Prévost, and M. Preisig, 2011: The effect of capillary pressure on the saturation equation of two-phase flow in porous media. International Journal for Numerical and Analytical Methods in Geomechanics, John Wiley & Sons, Ltd., doi:10.1002/nag.1022
[ Abstract ]
A complete and accurate simulation of two-phase flow in porous media requires knowledge of all the controlling physics (and values of physical parameters) that play a relevant role and an understanding of the effects of each one on the solution. Of particular concern here is the effect of capillary pressure and the length scale over which it is relevant. The goal of this paper is to provide guidance onto when to include the effects of capillary pressure in the model, and onto what are the resulting length scale restrictions if those effects are to be included.
Preisig, M., and Jean Hervé Prévost, 2011: Coupled multi-phase thermo-poromechanical effects. Case study: CO₂ injection at In Salah, Algeria. International Journal of Greenhouse Gas Control, doi:10.1016/j.ijggc.2010.12.006
[ Abstract ]
Coupled simulations of fluid injection and extraction in porous media are an important tool for assessing feasibility, safety and productivity of such operations. Different methods for coupling the fluid flow with geomechanics are currently used. In this paper we compare one-way and iterative coupling with full coupling. With the fully coupled two-phase thermo-poromechanical model we simulate the CO₂ injection operation, which is ongoing at In Salah, Algeria. The results suggest that pressure increase in the well and ground uplift for a given data set can accurately be modeled using our method. Finally, we illustrate the crucial effect of the temperature difference between injected fluid and reservoir on the possibility of creating and/or re-opening fractures perpendicular to the well in the cap rock that were observed in the field.
Preisig, M., and Jean Hervé Prévost, 2011: Fully coupled simulation of fluid injection into geomaterials with focus on nonlinear near-well behavior. International Journal for Numerical and Analytical Methods in Geomechanics, Wiley Online Library, doi:10.1002/nag.1039
[ Abstract ]
An important part of our global wealth depends on the extraction of fluids from porous media. More recently, sequestration of carbon dioxide (CO₂) into deep geological layers as a possible measure to mitigate climate change has increased interest in fluid injection into porous media. Sophisticated numerical models play an important role in managing the uncertainties related to the subsurface, and finite element methods are the most versatile tool allowing the coupling of fluid flow, geomechanics and other physical processes. This paper gives insight into two important aspects of fluid injection/extraction in porous media: the correct modeling of the bore hole through specification of initial stresses, which together with a fully coupled strategy allows simulation of nonlinear poromechanics, and the imposition of appropriate boundary conditions that allow the controlled injection/extraction of a total specified amount of fluid in an anisotropic porous medium, without exceeding a safe operating pressure.
Goumiri, I., and Jean Hervé Prévost, 2010: Cell to Node Projections: An Assessment of Error. International Journal for Numerical and Analytical Methods in Geomechanics, doi:10.1002/nag.927 1-10
[ Abstract ]
Reservoir simulators typically use cell-centered finite volume schemes and do not model directly the coupling of the flow processes with the geomechanics. Coupling of geomechanics with fluid flow can be important in many cases, but introducing fully coupled geomechanical effects in those simulators is not a trivial issue, because the geomechanics is better done by using the Galerkin vertex-centered finite element methods by which the solid displacements are computed at the vertices of the cells. This creates difficulties in interfacing cell variables with nodal variables. Uncoupled or loosely coupled models are used by many researchers/practitioners by which a reservoir model is coupled to a geomechanical model by staggering in-time flow and deformation via a sophisticated interface that repeatedly calls first flow and then mechanics. The method therefore requires projection of the reservoir cell variables onto the nodes of the geomechanics Galerkin finite element mesh. In this note, we attempt to quantify the errors associated with cell to node projection operations. For that purpose, we use a simple model of the pressure equation for a heterogeneous medium in one dimension. We are able to derive the exact analytical solution for this problem for both nodal and cell pressures. This allows us to compute the errors due to projection analytically, function of meshing refinement and permeability field variations. We compute upper and lower bounds for the errors, and analyze their magnitude for a variety of cases. We conclude that, in general, cell to node projection operations lead to substantial errors.
Huet, Bruno M., Jean Hervé Prévost, and George Scherer, 2010: Quantitative reactive transport modeling of Portland cement in CO₂-saturated. International Journal of Greenhouse Gas Control, 4, doi:10.1016/j.ijggc.2009.11.003 561-574
[ Abstract ]
A modular reactive transport model, Dynaflow^TM, is used to simulate the reactivity of cement in CO₂- saturated water of intermediate salinity (0.5 M). Methodology for coupling transport and geochemical modules is derived and its assumptions are discussed. The modules are coupled in a sequential iterative approach to accurately model: (1) mineral dissolution/precipitation (2) aqueous phase speciation and (3) porosity-dependent transport properties. Simulation results reproduce qualitatively the dissolution of cement hydrates (CH, C-S-H, AFm, AFt) and intermediate products (CaCO₃) that have been observed experimentally. However, when using a standard power law to relate effective transport properties to porosity, modeling and experimental results do not coincide; here, agreement between simulations and observations is obtained by modifying the functional dependence of effective diffusivity on mineralogy. Furthermore, for this particular system for which concentration gradients are the only driving force, the assumption of neglecting the mass balance of water or density changes might show its limits. Therefore, future work should investigate the likely need to account for reaction-driven advection.
Motley, M. R., and Jean Hervé Prévost, 2010: Simulation of transient heat conduction using one-dimensional mapped infinite elements. International Journal for Numerical Methods in Engineering, John Wiley & Sons, Ltd., doi:10.1002/nme.2847
[ Abstract ]
Many engineering problems exist in physical domains that can be said to be infinitely large. A common problem in the simulation of these unbounded domains is that a balance must be met between a practically sized mesh and the accuracy of the solution. In transient applications, developing an appropriate mesh size becomes increasingly difficult as time marches forward. The concept of the infinite element was introduced and implemented for elliptic and for parabolic problems using exponential decay functions. This paper presents a different methodology for modeling transient heat conduction using a simplified mesh consisting of only two-node, one-dimensional infinite elements for diffusion into an unbounded domain and is shown to be applicable for multi-dimensional problems. A brief review of infinite elements applied to static and transient problems is presented. A transient infinite element is presented in which the element length is time-dependent such that it provides the optimal solution at each time step. The element is validated against the exact solution for constant surface heat flux into an infinite half-space and then applied to the problem of heat loss in thermal reservoirs. The methodology presented accurately models these phenomena and presents an alternative methodology for modeling heat loss in thermal reservoirs.
Prévost, Jean H., and M. Preisig, 2010: Numerical simulation of CO2 injection into an aquifer and the importance of two-way coupling between fluid pressure and geomechanics. Conference of the Engineering Mechanics Institute, 8-11
Preisig, M., and Jean Hervé Prévost, 2010: Stabilization procedures in coupled poromechanics problems: A critical assessment. International Journal for Numerical and Analytical Methods in Geomechanics, doi:10.1002/nag.951 1-19
[ Abstract ]
Numerical solutions for problems in coupled poromechanics suffer from spurious pressure oscillations when small time increments are used. This has prompted many researchers to develop methods to overcome these oscillations. In this paper, we present an overview of the methods that in our view are most promising. In particular we investigate several stabilized procedures, namely the fluid pressure Laplacian stabilization (FPL), a stabilization that uses bubble functions to resolve the fine-scale solution within elements, and a method derived by using finite increment calculus (FIC). On a simple one-dimensional test problem, we investigate stability of the three methods and show that the approach using bubble functions does not remove oscillations for all time step sizes. On the other hand, the analysis reveals that FIC stabilizes the pressure for all time step sizes, and it leads to a definition of the stabilization parameter in the case of the FPL-stabilization. Numerical tests in one and two dimensions on 4-noded bilinear and linear triangular elements confirm the effectiveness of both the FPL- and the FIC-stabilizations schemes for linear and nonlinear problems.
Peters, Catherine A., George Scherer, Michael Celia, Jean Hervé Prévost, T. C. Onstott, P. F. Dobson, C. M Oldenburg, B. Freifeld, J. Birkholzer, J. Wang, S. Benson, and T. J. Phelps, et al., in press: Collaborative Research: DUSEL CO₂, A Deep Underground Laboratory for Geologic CO₂ Sequestration Studies: A proposal for the conceptual design of the facility and experiments. NSF. 0/09.
[ Abstract ]
Princeton University and Lawrence Berkeley National Laboratory have forged a new collaboration to examine the feasibility and risks of carbon sequestration, a method of countering global warming by storing greenhouse gases deep underground. To develop a sound understanding of carbon sequestration, we will build a deep underground laboratory to study the processes of trapping and storing CO₂, including the risks of unintended leakage. It will be part of the new DUSEL facility at the Homestake mine in South Dakota. The �DUSEL CO₂, facility will make the United States the only country with a deep underground laboratory for controlled study of geologic carbon sequestration, providing a unique opportunity for global leadership. The findings from these unique experiments will advance carbon management technology worldwide and help reduce global greenhouse gas emissions. The features and capabilities of the planned facility are unprecedented. The experimental design exploits the nearly half-kilometer vertical extent of existing �sandline� borings at Homestake. Pipes will be installed within the sandlines to serve as long flow columns. These columns will contain the CO₂, and allow experimentation at the same pressure and temperature conditions as in deep subsurface reservoirs. Fill materials will mimic sedimentary layering, as well as cements in plugged wells. Instrumentation will enable detailed monitoring of flow, pressure, temperature, brine composition, geomechanics, and microbial activity. As part of the initial suite of experiments, we plan to simulate a leak in which CO₂, changes from a supercritical fluid to a subcritical gas as the pressure drops during upflow over tens to hundreds of meters. We will test for possible acceleration in CO₂, flow due to increasing buoyancy. Also, we will examine the interactions of CO₂, with cap-rocks and well cements, and determine whether CO₂, will enlarge flow pathways or cause selfsealing. Finally, we will investigate the effects of anaerobic, thermophilic bacteria on CO₂, conversion to methane and carbonate. This project is being led by researchers at Princeton and LBNL, and involves no-cost collaboration with individuals at ORNL, Stanford University, Schlumberger and the U.S. DOE NETL. During this three-year project, the team is working to (i) prioritize future experiments that will be conducted at DUSEL CO₂, (ii) build models that simulate experimental conditions and predict process dynamics, and (iii) develop a Work-Breakdown Structure (WBS) schedule for design, procurement, construction, operation and deconstruction of the facility over the facility lifetime. International awareness about DUSEL CO₂, is being fostered through international workshops and formation of an International Advisory Committee. Also, we are collaborating with other DUSEL scientists on education and outreach about �deep science,� with particular focus on climate change and energy solutions. DUSEL education and outreach activities are focused on Native American communities in South Dakota and operation of the Visitor Center at the Sanford Lab at Homestake. To inspire and educate the next generation of leaders, we are involving undergraduate and graduate students in DUSEL CO₂, research at Princeton University.
Scherer, George, Jean Hervé Prévost, and Z. H. Wang, 2009: Bending of a Poroelastic Beam with Lateral Diffusion. International Journal of Solids and Structures, 46(18-19), doi:10.1016/j.ijsolstr.2009.05.016 3451-3462
[ Abstract ]
Bending an elastic beam leads to a complicated 3D stress distribution, but the shear and transverse stresses are so small in a slender beam that a good approximation is obtained by assuming purely uniaxial stress. In this paper, we demonstrate that the same is true for a saturated poroelastic beam. Previous studies of poroelastic beams have shown that, to satisfy the Beltrami�Michell compatibility conditions, it is necessary to introduce either a normal transverse stress or shear stresses in addition to the bending stress. The problem is further complicated if lateral diffusion is permitted. In this study, a fully coupled finite element analysis (FEA) incorporating the lateral diffusion effect is presented. Results predicted by the �exact� numerical solution, including load relaxation, pore pressure, stresses and strains, are compared to an approximate analytical solution that incorporates the assumptions of simple beam theory. The applicability of the approximate beam-bending solution is investigated by comparing it to FEA simulations of beams with various aspect ratios. For �beams� with large width-to-height ratios, the Poisson effect causes vertical deflections that cannot be neglected. It is suggested that a theory of plate bending is needed in the case of poroelastic media with large width-to-height ratios. Nevertheless, use of the approximate solution yields very small errors over the range of width-to-height ratios (viz., 1�4) explored with FEA.
Huet, B. J., Jean Hervé Prévost, and George Scherer, 2008: Reactive Transport Modeling of Cement Degradation in Brine: Effect of pH and CO₂ content. Geophysical Review, 10,
[ Abstract ]
As a CO₂ plume is moving into a reservoir, the chemistry of the fluid at the bottom of an abandoned well changes in successive stages. The first one consists in an increase of the CO₂ content of the brine, while brine saturation remains close to its initial value. A modular reactive transport model, Dynaflow, is used to analyze the reactivity of well cement paste during this first stage. The geochemical module accurately models aqueous speciation and mineral dissolution and/or precipitation within the porous material. Hydrated cement paste is found to dissolve in brines with various content in CO₂. Simulation of a reference case is successfully compared with experimental results, in terms of mineral zoning and dissolution rate. Between pH 2.4 and 5.0, the CO₂ content of a 0.5 M brine controls the degradation rate of cement whereas the pH does not affect it meaningfully. A minimum degradation rate is obtained when the CO₂ molality equals the total molality of aqueous calcium in equilibrium with portlandite. This minimum is related to the maximal amount of calcite precipitated and the relative decrease of the diffusivity within the calcite rich zone.
Wang, Z. H., Jean Hervé Prévost, and O. Coussy, 2008: Bending of Fluid-Saturated Linear Poroelastic Beams with Compressible Constituents. International Journal for Numerical and Analytical Methods in Geomechanics, 33(4), doi:10.1002/nag.722 425-447
[ Abstract ]
Analytical solutions are presented for fluid-saturated linear poroelastic beams under pure bending. The stress-free boundary condition at the lateral surfaces is satisfied in the St Venant�s sense and the Beltrami� Michell compatibility conditions are resolved rigorously, rendering the flexure of the beams analytically tractable. Two sets of formulations are derived based on the coupled and uncoupled diffusion equations respectively. The analytical solutions are compared with three-dimensional finite element simulations. Both sets of analytical formulations are capable of capturing exactly both the initial (undrained) and the steady-state (fully drained) deflection of the beams. However, the analytical solutions are found to be deficient during the transient phase. The cause for the deficiency of the transient analytical solutions is discussed. The accuracy of the analytical solutions improves as Poisson�s ratio and the compressibility of the constituents of the porous beam increase, where the St Venant�s edge effect at the lateral surfaces is mitigated.
Huet, B. J., Jean Hervé Prévost, and George Scherer, June 2007: Cement reactivity in CO₂ saturated brines: use of a reactive transport code to highlight key degradation mechanisms. Eurotherm Seminar N 81 Reactive Heat Transfer in Porous Media, Albi, France, http://eurotherm81.enstimac.fr/papers_pdf/22-Huet.pdf,
[ Abstract ]
A modular reactive transport code is proposed to analyze the reactivity of cement in CO₂ saturated brine. The coupling of the transport module and the geochemical module within Dynaflow^TM is derived. Both modules are coupled in a sequential iterative approach to accurately model: (1) mineral dissolution/precipitation and (2) porosity dependent transport properties. Results of the model reproduce qualitatively the dissolution of cement hydrates (C-H, C-S-H, AFm, AFt) and intermediate products (CaCO₃) into the brine. Slight discrepancies between modeling and experimental results were found concerning the dynamics of the mineral zoning. Results suggest that the power law relationship to model effective transport properties from porosity values is not accurate for very reactive case.
Huet, B. J., R. Fuller, and Jean Hervé Prévost, 2007: Development of a coupled geochemical transport code to simulate cement degradation in CO₂ saturated brine. Proceedings of the 8th International Conference on Greenhouse Gas Control Technologies (GHGT-8), https://www.princeton.edu/~cmi/research/Storage/Presentations/DevelopmentCoupledGeochemical.pd,
[ Abstract ]
This work aims at modeling well-bore leakage of carbon dioxide (CO₂) from sequestration reservoirs. The leakage of CO₂ is a function of the geometry of the low permeability path and of the boundary conditions. Furthermore, the CO₂ flow can also be strongly influenced by the chemical reactivity of cement, leading either to the sealing or to the widening of the annulus. Thus, a multiphase transport model that aims at assessing CO₂ leakage along high permeability paths must account for the reactivity of the porous environment. Therefore a geochemical module must be integrated. This study presents preliminary results of the coupling of a geochemical module with a transport module. Governing equations of the two modules are introduced. Results of benchmark simulations of chemical degradation of cement paste (CEM I) in pure deionized water are presented. The influence of the different terms of the transport equation on mineral profile is discussed.
Fuller, R., Jean Hervé Prévost, and M. Piri, 2006: Three-Phase Equilibrium and Partitioning Calculations for CO₂ Sequestration in Saline Aquifers. Journal of Geophysical Research, 111(B06207), doi:10.1029/2005JB003618
[ Abstract ]
We show how the use of appropriate variables results in a flash calculation that uses only equilibrium constraints; it is thus not necessary to solve the mass balance equations self-consistently with the equilibrium equations. We use this implicit material balance in flash calculation. We show its advantages over the current approach that uses an explicit material balance. For the flash calculation for CO₂ storage in brine aquifers, use of appropriate variables also allows us to find the dew, bubble, and precipitation points where the liquid, vapor, and solid salt phases, respectively, emerge. Our calculation includes the water content of the vapor phase, which arises from evaporation of the brine. Evaporation leads to increased brine salinity, which results in a large reduction in CO₂ solubility in the salting-out effect, and eventually in precipitation of solid salt and ultimately the disappearance of the liquid phase. The flash calculation also relies on our derivation of fugacities for H₂O and CO₂ in both the brine and the vapor phase.
Huet, B. J., R. Fuller, and Jean Hervé Prévost, March 2006: Development of a geochemical code to assess cement reactivity in CO₂/brine mixtures. Wellbore Integrity Workshop, Princeton University, http://www.princeton.edu/~cmi/research/Storage/Papers/DevelopmentGeochemicalCodeCO2SC.pdf, 164-168
[ Abstract ]
This work aims at modeling well-bore leakage of carbon dioxide (CO₂) from sequestration reservoirs. The leakage of CO₂ is a function of the geometry of the low permeability path and of the boundary conditions. Furthermore, the CO₂ flow can also be strongly influenced by the chemical reactivity of cement, leading either to the sealing or to the widening of the annulus. Thus, a multiphase transport model that aims at assessing CO₂ leakage along high permeability paths must account for the reactivity of the porous environment. Therefore a geochemical module must be integrated. This study presents preliminary results of the coupling of a geochemical module with a transport module. Governing equations of the two modules are introduced. Results of benchmark simulations of chemical degradation of cement paste (CEM I) in pure deionized water are presented. The influence of the different terms of the transport equation on mineral profile is discussed.
Huet, B. J., R. Fuller, Jean Hervé Prévost, and George Scherer, May 2006: Numerical simulation of multiphase flow of CO₂ along low permeability path up the wells. Introduction of the interactions with cement. Proceedings of the Fifth Annual Conference on Carbon Capture & Sequestration, Alexandria, Virginia,
[ Abstract ]
This work aims at modeling well-bore leakage of Carbon Dioxide (CO₂) from sequestration reservoirs. The leakage of CO₂ is function of the geometry of the low permeability path and boundary conditions. However, the CO₂ flow can also be strongly influenced by the chemical reactivity of cement leading either to the sealing or to the widening of the annulus. This study presents results of the integration of a geochemical module into a robust three-phase transport module developed by Fuller et al. [1]. The numerical model assesses the chemical and physical integrity of cement in injection and/or abandoned sealed wells. The geochemistry part of the simulator assumes local chemical equilibrium. It takes into account the reactivity of cement, i.e. both mineral solid phase changes, like portlandite dissolution and calciium carbonate formation, and aqueous speciation in the interstitial solution. As a result of minerals dissolution and formation, the changes in porosity and the related changes in diffusion and permeability properties of cement are also evaluated. The simulator allows the study of the influence of the well geometry, e.g., the initial width of the annulus between hydrated cement and steel casing, or between hydrated cement and reservoir stone. Both diffusion and advection transport mechanisms are studied separately to account for the different cement pressure environments. Results indicate drastically different degradation rates for cement. Thus, the mean width of the annulus is a key parameter to assess the reliability of injection or abandoned wells.
Piri, M., Jean Hervé Prévost, and R. Fuller, May 2005: Carbon Dioxide Sequestration in Saline Aquifers: Evaporation, Precipitation and Compressibility Effects. Proceedings of the 4th Annual Conference on Carbon Capture and Sequestration, Alexandria, VA, http://www.princeton.edu/~cmi/research/Storage/Papers/CO2SequestrationSalineAquifers.pdf,
[ Abstract ]
A compositional reservoir simulator is developed that is capable of modeling multicomponent, isothermal multiphase flow of compressible fuids through deformable porous media. The simulator is used to study the detailed physics associated with the transport of dfferent components in a three-phase system encountered during Carbon Dioxide (CO₂) sequestration in deep saline aquifers. The model benefits from a robust three-phase (brine - solid salt - supercritical CO₂) flash module developed by Fuller et al. [1] to partition materials into different phases that are considered to be in thermodynamic equilibrium. As an example we model the radial injection of supercritical CO₂ in a deep saline aquifer taking into account dispersion and compressibility of �uids. The injected CO₂ resides in a dense liquid-like supercritical phase and also dissolves into the brine. The results illustrate the evolution of one- , two- and three-phase regions in the system. We encounter a dried region close to the injection well where salt precipitation into a solid phase is a direct consequence of complete evaporation of the residual liquid left behind the displacing front. Effects of evaporation on the amount of dissolved CO₂, salting out efect, is studied. We demonstrate that proper treatment of evaporation and precipitation provides solutions that deviate in the near term from scaling with the conventional similarity variable (R²/t) for radial flow. However, scaling does occur after all the transients have died out. Porosity change due to salt precipitation and matrix compressibility which in turn alters absolute permeability are also taken into account. Effects of fluid and matrix compressibilities and brine salinity on amount of CO₂ dissolved in the liquid phase are also analyzed. We also present results of two-dimensional simulations in which effects of hysteresis on trapping of CO₂ have been studied.
Prévost, Jean H., R. Fuller, A. Altevogt, R. Bruant, and George Scherer, 2005: Numerical Modeling of Carbon Dioxide Injection and Transport in Deep Saline Aquifers. Proceedings of the 7th International Conference on Greenhouse Gas Control Technologies, (GHGT-7), http://www.princeton.edu/~cmi/research/Storage/Papers/NumericalModelingCarbonDioxide.pdf, 2189-2193
[ Abstract ]
We describe the development of a compositional resevoir simulator capable of modeling multiphase transport of CO₂ in a brine aquifer, and results are provided which illustrate the evolution of a 2-phase fluid system in which the injected CO₂ resides in a dense supercritical phase and also dissolves into the liquid phase. Salt precipitation into a solid phase is found to occur close to the injection well where the gas phase dominates.
Scherer, George, Michael Celia, Jean Hervé Prévost, , R. Bruant, A. Duguid, R. Fuller, S. Gasda, M. Radonjic, and W. Vichit-Vadakan, 2005: Leakage of CO₂ through Abandoned Wells: Role of Corrosion of Cement. The CO₂ Capture and Storage Project (CCP), Volume II, Chapter 10, 823-844
[ Abstract ]
The potential leakage of CO₂ from a geological storage site through existing wells represents a major concern. An analysis of well distribution in the Viking Formation in the Alberta basin, a mature sedimentary basin representative of North American basins, shows that a CO₂ plume and/or acidified brine may encounter up to several hundred wells. A review of the literature indicates that cement is not resistant to attack by acid, but little work has been reported for temperatures and pressures comparable to storage conditions. Therefore, an experimental program has been undertaken to determine the rate of corrosion and the changes in properties of oil well cements exposed to carbonated brine. Preliminary results indicate a very high rate of attack, so it is essential to have accurate models of the composition and pH of the brine, and the time that it will remain in contact with cement in abandoned wells. A model has been developed that incorporates a flash calculation of the phase distribution, along with analysis of the fluxes and pressure of the liquid, solid and vapor phases. A sample calculation indicates that wells surrounding the injection site may be in contact with the acidified brine for years.

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