Fundamentals of foam transport in porous media

Kovscek, A. R.; Radke, Clayton J.

doi:10.2172/10192736

Cited by 167 publications

(208 citation statements)

References 13 publications

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“…Co-injection or alternate injection of surfactant solution and CO 2 result in the formation of foam in porous media. Foam is a gas-liquid mixture where the liquid containing the surfactant forms a continuum wetting the rock whereas a part or all of the gas is made discontinuous by thin liquid films called lamellae ([Kovescek and Radke, 1994] and [Gauglitz et al, 2002]). …”

Section: Co 2 As Oil-recovery Agentmentioning

confidence: 99%

Foam assisted CO2-EOR; Concepts, Challenges and Applications

et al. 2013

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Foam assisted CO 2 enhanced oil recovery has attracted increasing attention of oil companies (operators and service companies) and research institutions mainly due to the potentially high benefit of foam on CO 2 -EOR. Miscible and immiscible CO 2 flooding projects are respectively proven and potential EOR methods. Both methods have suffered from limited efficiency due to gravity segregation, gas override, viscous fingering and channeling through high permeability streaks. Numerous theoretical and experimental studies as well as field applications have indicated that foaming of CO 2 reduces its mobility, thereby helping to control the above negative effects. However, there are still various conceptual and operational challenges, which may compromise the success and application of foam assisted CO 2 -EOR. This paper presents a critical survey of the foam assisted CO 2 -EOR process to reveal its strengths, highlight knowledge gaps and suggest ways. The oil recovery mechanisms involved in CO 2 foam flood, the effect of gaseous and soluble CO 2 on the process, synergic effect of foaming agent and ultra-low IFT surfactants, logistic and operational concerns, etc. were identified as among the main challenges for this process. Moreover, the complex flow behaviour of CO 2 , oil, micro-emulsion and brine system dictates a detailed study of the physical-chemical aspects of CO 2 foam flow for a successful design. Unavailability of reliable predictive tools due to the less understood concepts and phenomena adds more challenges to the process results and application justifications. The study highlights the recent achievements and analysis about foam application and different parameters, which cannot be avoided for a successful foam assisted CO 2 flood design and implementation. Accordingly, the study also addresses prospects and suggests necessary guidelines to be considered for the success of CO 2 foam projects. SPE 165280sweep efficiency in CO 2 -floods can be high, and the displacement efficiency of a miscible CO 2 flood often exceeds 90%. However, the sweep efficiency of CO 2 processes is often poor. Limitations of the current CO 2 -EORCO 2 would be much more widely used if it were abundantly available (Orr Jr., 2003). Natural sources, by-product of gas treatment units, and combustion processes could be supply sources of CO 2 . However, the present technologies of CO 2 capture and pressurization require energy which would result in a decreased overall energy efficiency and added cost. To recover additional oil in a CO 2 -EOR process, CO 2 is generally injected into the reservoir as a supercritical fluid (Sc-CO 2 ). Sc-CO 2 viscosity is lower than water and most crude oils, which can lead to a number of conformance and mobility issues, and instability in the displacement front, as shown in Fig. 1. Due to the adverse mobility ratio, fingers of CO 2 grow from the displacement front, and cause premature breakthrough, and inefficient CO 2 utilization. Furthermore, the tendency of lower density CO 2 to migrate toward the upper p...

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Section: Co 2 As Oil-recovery Agentmentioning

confidence: 99%

Foam assisted CO2-EOR; Concepts, Challenges and Applications

et al. 2013

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“…Therefore no separate material balance for surfactant is needed. As noted, in foam processes, gas properties depend on bubble texture as well as water saturation (Falls et al , 1989Kovscek and Radke 1994;Rossen 1996). Therefore modeling requires, in addition to the water mass-balance equation (Equation (2)), a so-called population-balance equation: where n D ≡ n f /n max is the dimensionless bubble texture and n max is an upper limit to foam texture (see Appendix A for more detail).…”

Section: Governing Equations In Foam Processesmentioning

confidence: 99%

“…Many papers introduce or discuss a population-balance foam model illustrated by simulation of co-injection of gas and liquid or gas injection into a medium with surfactant solution, but no gas initially present (Kovscek and Radke 1994;Bertin et al 1998;Myers and Radke 2000;Kam et al 2007;Kam 2008;Chen et al 2010). Chen et al (2010) show close agreement between co-injection foam simulations assuming local equilibrium and with full foam dynamics (see also Rossen et al 1999), except for better refinement of the traveling wave at the shock front with the population-balance model.…”

Section: Transient Dynamic-foam Simulationmentioning

confidence: 99%

Multiple Foam States and Long-Distance Foam Propagation in EOR Displacements

Ashoori

Marchesin

Rossen

2012

SPE Improved Oil Recovery Symposium

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Foam reduces gas mobility and thereby improves sweep in enhanced-oil-recovery processes. The "strength" of foam describes the degree of gas-phase mobility reduction. Experiments show that foam can exist in three different states (weak foam, intermediate foam, and strong foam) at the same injection rate. Strong foam with fine bubbles achieves better sweep efficiency than weak foam with coarse bubbles. In experiments, creation of strong foam is triggered by an increase in superficial velocity; thereafter injection rate can be reduced to lower values and strong foam remains at velocities at which weak foam was previously observed.It is important to determine whether strong foam created near an injection well can propagate to large distances from the well, where superficial velocity is much smaller. Here, we study strong-foam propagation with finite-difference simulations and Riemann solutions, applying a population-balance foam model that represents the multiple steady states of foam.Our simulations show that strong foam cannot directly displace the initial high-water-saturation bank initially in the reservoir at low superficial velocities; it pushes a weak-foam state with lower velocity that in turn displaces the bank ahead. Our traveling-wave solutions show that strong foam propagates more slowly as superficial velocity decreases and stops propagating at yet lower superficial velocities, in agreement with experiment. Failure of propagation occurs at superficial velocities greater than that at which the strong-foam state disappears; it raises concerns for long-distance propagation of strong foam created near injection well. In the context of the model, it is not extraordinary destruction of foam at the front that slows the propagation of strong foam, but failure of foam (re-)generation at the front. Our model also represents for the first time a process where strong foam is created near the exit of a core and then propagates upstream, as seen in some experiments.

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“…The steady-state rheology of foam is complex; it depends not only on the effective gas viscosity at fixed bubble size, which is known to be shear-thinning (Hirasaki and Lawson,1985;Falls et al, 1989), but on how bubble size and gas trapping (which affects gas relative permeability) change with superficial velocity Rossen, 1992;Kovscek and Radke, 1994;Tang and Kovscek, 2006). To a reasonable approximation, steady-state foam in porous media can be approximated as a powerlaw fluid at fixed quality (gas fraction of total superficial velocity) (Alvarez et al, 2001;Mamun et al, 2002;Rong, 2002;Kim et al, 2005).…”

Section: Power-law Rheologymentioning

confidence: 99%

Well Stimulation and Gravity Segregation in Gas Improved Oil Recovery

Jamshidnezhad

Shen

Kool³

et al. 2008

SPE International Symposium and Exhibition on Formation Damage Control

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Models for gravity segregation in gas improved oil recovery (IOR) indicate that the distance injected gas and water travel together before complete segregation scales with the injection rate Q. Therefore, in cases where injection pressure is limiting, reducing skin resulting from damage at the wellbore face directly increases volumetric sweep of gas in IOR. Even in the absence of damage at the wellbore face, most of the injection pressure is dissipated near the well, but most of the segregation occurs much further from the well. Therefore, if injection pressure is limited, increasing mobility near the injection well has a large impact on Q, with a direct benefit in delaying gravity segregation. There is also a relatively small increase in gravity segregation in the near-well region. An analytical model for gravity segregation in homogeneous reservoirs can be extended to a case where permeability is stimulated within a cylindrical region inside a larger cylindrical reservoir. The effect of this stimulation in increasing Q at fixed injection pressure can be estimated as well. One can increase the volume swept by gas before segregation by as much as 170%, though a large volume must be stimulated to reach this optimum.The model represents schematically a number of ways proposed in gas IOR for delaying segregation beyond the possibilities with uniform, steady co-injection of Newtonian fluids: alternate injection of gas and liquid (WAG, or SAG with foam); injection of gas above water; and injection of shear-thinning foam. In all these cases the process gives higher mobility near the well, allowing an increase in injection rate, and thereby increases the distance to the point of segregation.The model can be extended directly to the case of shear-thinning (power-law) foam. One obtains a differential equation for the segregation process, in place of the algebraic equation that results for Newtonian fluids. In the limit of extremely shearthinning behavior, it is possible to double the distance to the point of segregation with no increase in injection pressure. Simulations fit the theoretical prediction well. SPE 112375where Q is total volumetric injection rate of gas and water, kv vertical permeability, ρw and ρg densities of water and gas, respectively, g gravitational acceleration, and λrt m the total relative mobility in the mixed zone.Using the method of characteristics, Rossen and van Duijn (2004) show that this equation is rigorously correct making only the usual assumptions of fractional-flow theory:1. The reservoir is homogeneous, although possibly anisotropic (kv ≠ kh).2. The reservoir is cylindrical with an open outer boundary, and the reservoir is confined by no-flow barriers above and below. 3. The injection well is completed over the entire height of the reservoir. 4. The region of interest is at steady state, with steady injection of fluids at volumetric rate Q and injected fractional flow of water fw=fw J . This implies that any remaining oil in the region of interest is at its residual saturation and immobi...

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Fundamentals of foam transport in porous media

Cited by 167 publications

References 13 publications

Foam assisted CO2-EOR; Concepts, Challenges and Applications

Foam assisted CO2-EOR; Concepts, Challenges and Applications

Multiple Foam States and Long-Distance Foam Propagation in EOR Displacements

Well Stimulation and Gravity Segregation in Gas Improved Oil Recovery

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