Foam flooding

Measuring the radius of a foam lamella plateau border where it initially contacts the oil or of an emulsified drop 

Determining the interfacial tension between the foaming solution and the oil 

Correlating these measurements with a mathematical model to obtain a value indicative of the oil imbibing properties of the foam 

The foam, having a viscosity greater than the displacing medium, will preferentially accumulate in the well-swept and/or higher permeability zones of the formation. The displacing medium is thus forced to move into the unswept or underswept areas of the formation. It is from these latter areas that the additional oil is recovered. However, when a foam is used to fill a low oil content area of the reservoir, the oil contained therein is, for all practical purposes, lost. This is because the foam functions to divert the displacement fluid from such areas [1574-1576]. 

Foam stability in the presence of oil can be described from thermodynamics in terms of the spreading and entering coefficients S and E respectively. These coefficients are defined as follows  

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The dependence of the expansion ratio of a foam produced by the barbotage technique allows to explain the change in the characteristics of the liquid carry-away with the foam (flooding coefficient or volumetric factor [89], see Section 10.3.2). When other foam producing modes are employed (shaking or pouring the solution, etc.), the dependence of the initial expansion ratio on the properties of the foaming solution is much more complicate and sometimes it is not possible even to explain it qualitatively. 

CO2 floods at pressures above 10 MPa (49). Only flooding experiments were used to choose surfactants in this first extension of low-pressure foam flooding to high-pressure, C02-miscible flooding. 

T. "Enhanced Oil Recovery by COj Foam Flooding," Report, Contract No. DE-AC21-78MC03259 (February... 

A study of the effect of pore geometry on foam formation mechanisms shows that snap-off" bubble formation is dominant in highly heterogeneous pore systems. The morphology of the foams formed by the two mechanisms are quite different. A comparison of two foam injection schemes, simultaneous gas/surfactant solution injection (SI) and alternate gas/surfactant solution injection (GDS), shows that the SI scheme is more efficient at controlling gas mobility on a micro-scale during a foam flood. 

The PS micromodel, on the other hand, had fewer pore connections, and the pores were of more uniform size consequently, it was almost completely swept of liquid in the GDS foam flood (Test... 

Note that the oil-wet results are considerably better than the water-wet EOR recoveries, except for the secondary WAS process in the oil-wet model. The foam results were better for the oil-wet pack for both the secondary and tertiary cases than they were in the water-wet pack. We attribute the poorer performance of the water-wet pack to a higher proportion of oil which is blocked from contact with the 002 at the water saturations which occur in WAG and foam flooding. This apparently cuts the EOR recovery to about half of that observed in the oil-wet pack for equivalent water saturations. 

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