Mechanisms vertical sweep

One obvious mechanism in polymer flooding is the reduced mobility ratio of displacing fluid to the displaced fluid so that viscous Angering is reduced. When viscous Angering is reduced, the sweep efficiency is improved, as shown in Figure 1.2. This mechanism is discussed extensively in the waterflooding literature it is also discussed in Chapter 4. When polymer is injected in vertical heterogeneous layers, crossflow between layers improves polymer allocation in the vertical layers so that vertical sweep efficiency is improved. This mechanism is detailed in Sorbie (1991). 

In this paper, numerical simulation, scaling theory and experiments have been used in order to study the recovery mechanism operating in the polymer flooding of macroscopically layered systems. All of the work has centred on vertical sweep improvement in which the local water/oll mobility ratio has been close to unity. The main conclusions are as follows ... 

An important application of polymers in several areas of the world is in the improvement of waterflooding performance in highly inhomogeneous reservoirs. In particular, polymers can reduce the harmful effects of high-permeability layers in a vertically stratified system and so reduce watercut and improve vertical sweep efficiency. Polymers can act by a combination of two mechanisms ... 

In the planning of a field polymer flood, it would therefore not be necessary to carry out 2-D floods in order to reproduce the recovery mechanism if improved vertical sweep were the objective of the polymer flood. Numerical simulation would simply be used to investigate these mechanisms. However, it is interesting to study experimental results from scaled layered systems since certain issues can be illustrated in particularly instructive ways. For example, the fluid dynamics of viscous slug breakdown or the flow patterns in the placement of viscous polymer slugs can be visualised very directly using such experiments (Sorbie etal, 1990). 

Generally the log is rotated so that it can be correctly presented to the scanner, usually with the sweep of the log lying in the vertical plane. The log is picked up by a charger and passed through the scanner. The computer then instructs the setworks to correctly position the log before passing it on to the infeed mechanism of the... 

These filters, often called mechanized Nutsches , are circular vessels provided with a cover, through which passes a shaft carrying a stirrer. The stirrer can sweep the whole area of the filter cake and it can be lowered or raised vertically as required. During the filtration process the stirrer is in the top position, if necessary in motion in order to prevent the formation of an... 

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