Foaming/flooding

Figure 11 shows all of these core-flood foam performance results plotted versus the logarithm of the lamella number. A strong correspondence is obtained with the logarithm of lamella number. That the trend between mobility reduction and lamella number is so consistent among the different systems is remarkable considering that the core-flood results... 

A single model of foam-oil interaction cannot account for all situations. Certain foam—oil sensitivity models can be reconciled with both microvisual studies and core-flood foam effectiveness measurements, all for a wide variety of foams, oils, porous media, and other experimental conditions. However, exceptions are readily found. In an earlier section, the models of emulsification—imbibition, pseudoemulsion film thinning, entering, and spreading were introduced. Cases in favor of, and exceptions to, the applicability of each of these can be found in the literature. Although this situation prompts some inclination to search for additional mechanisms, the truth may be that all the models presented have some validity and that one or another valid mechanism is most significant in a given situation. 

Column Field Testing Flooding, Foaming, Efficiency... 

Overhead temperature on stripper > design reflux flowrate too low/[flooded] / [foaming] /feed contaminated with light hydrocarbons. 

The focus of more recent work has been the use of relatively low concentrations of additives in other oil recovery processes. Of particular interest is the use of surfactants (qv) as CO2 (4) and steam mobiUty control agents (foam). Combinations of older EOR processes such as surfactant-enhanced alkaline flooding and alkaline—surfactant—polymer flooding show promise of improved cost effectiveness. 

The WAG process has been used extensively in the field, particularly in supercritical CO2 injection, with considerable success (22,157,158). However, a method to further reduce the viscosity of injected gas or supercritical fluid is desired. One means of increasing the viscosity of CO2 is through the use of supercritical C02-soluble polymers and other additives (159). The use of surfactants to form low mobihty foams or supercritical CO2 dispersions within the formation has received more attention (160—162). Foam has also been used to reduce mobihty of hydrocarbon gases and nitrogen. The behavior of foam in porous media has been the subject of extensive study (4). X-ray computerized tomographic analysis of core floods indicate that addition of 500 ppm of an alcohol ethoxyglycerylsulfonate increased volumetric sweep efficiency substantially over that obtained in a WAG process (156). 

Thermally stable foam additives, such as alkylaryl sulfonates and C -C g alpha-olefin sulfonates, are being used in EOR steam flooding for heavy od production. The foam is used to increase reservoir sweep efficiency (178,179). Foaming agents are under evaluation in chemical CO2 EOR flooding to reduce CO2 channeling and thus increase sweep efficiency (180). 

Ffactor The vapor kinetic-energy parameter, often used as a correlating term for flooding velocity, foam density, etc. 

Figure 8-137. Flooding capacity, sieve trays weir height is less than 15% of tray spacing low- to non-foaming system hole area at least 10% hole sizes Ms-in. to M-in. dia. surface tension = 20 dynes/cm. Used by permission, Fair, J. R., Petro/Chem. Engineer, Sept (1961), p. 46, reproduced courtesy of Petroleum Engineer International, Dallas, Texas.

Removing water from the lean oil. Installation of water draws and/ or a coalescer can improve recovery. Water can become trapped in the tower and cause poor tray efficiencies, foaming, and premature flooding. 

The results at 75°C are consistent with results of steam foam sand pack floods reported by Muys and Keizer [63]. They observed lower sand pack permeability with increased AOS carbon number. Isaacs et al. reported similar results [64]. 

Several surfactants were studied in ambient-pressure foam tests, including alcohol ethoxylates, alcohol ethoxysulfates, alcohol ethoxyethylsulfonates, and alcohol ethoxyglycerylsuUbnates [210]. Surfactants that performed well in the 1-atm foaming experiment were also good foaming agents in site cell and core flood experiments performed in the presence of CO2 and reservoir fluids under realistic reservoir temperature and pressure conditions. 

C12 to Ci5 alcohols and a-olefin sulfonate are highly effective with steam foaming agents or carbon dioxide foaming agents in reducing the permeability of flood-swept zones [1372]. 

B. G. Hurd. Method for using foams to improve alkaline flooding oil recovery. Patent US 4981176,1991. 

T. Zhu, A. Strycker, C. J. Raible, and K. Vineyard. Foams for mobility control and improved sweep efficiency in gas flooding. In Proceedings Volume, volume 2, pages 277-286.11th SPE/DOE Impr Oil Recovery Symp (Tulsa, OK, 4/19-4/22), 1998. 

The vapor flooding velocity can now be calculated from Equation 8.3 assuming a foaming factor of 0.9 ... 

Surface Behavior. Most extraction processes deal with several phases. At the boundaries between these phases, an interface exists which can be populated with or depopulated of polymer. Situations in which the polymer should accumulate at the surface of one phase are 1. the flocculation of clays and fines or 2. the formation of foams, while situations in which the polymer should depopulate the surface of the phase boundary are 3 minimizing adsorption in mineral acid leaching or 4. minimizing surface tension with surfactants in oil recovery by miscible flooding.,... 

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