Flooding heterogeneity’ control flood

For a heterogeneity control polymer flood, since the recovery mechanism is 2-D in nature (cross-flow), it is simply not present in an oil displacement experiment in a 1-D reservoir core. Therefore, nothing can be learned from polymer flooding field cores if this is the proposed oil recovery mechanism in the pilot flood. Indeed, this could be positively misleading, since the local (linear) mobility ratio in the system could be close to unity and a waterflood... 

Preliminary 2-D evaluation calculations. The first set of calculations which should be carried out is during the phase immediately following the original screening study. Alternatively, the reservoir under consideration may be a fairly obvious candidate for polymer flooding and may have been selected on that basis. Whatever the reason for the selection, there will also be some indication whether the application is for viscosity or heterogeneity control. It is also presumed that at least a simple simulation model of the reservoir is available or can be constructed fairly quickly. 

If the polymer application is for viscosity control, then the simple model may be a 2-D areal or simple layered five-spot pattern the well locations will be known, and any faults that are known should be included using transmissibility modifiers. In this areal system, the key features in the calculation are that the oil viscosity is correct and reasonable estimates of the reservoir relative permeabilities are available. For a heterogeneity control flood, a multilayer cross-section similar to the eight-layer system described in Chapter 8 may be selected. Here, the most important factor is to get the layering structure and layer permeabilities correct, especially the permeability contrast between the high-permeability layer(s) and the position of this layer. The value of the kjk ratio may also be very important in this type of polymer flood, but it may be sufficient to know that it is > 0.05 for example (see Chapter 8). In such an application, the mobility ratio may be close to... 

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. 

Screening criterion Heterogeneity Viscosity control control polymer polymer flood flood Comment... 

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