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In some cases, the specific geological features of
formation make it necessary to place injection wells right on the
drainage boundary (so-called marginal flooding).
Marginal flooding. Marginal flooding is used when
injection wells located in oil-bearing part of deposit near to
external oil-bearing contour (Fig. 4.3). It is used in low mobility or
real estate WOC. Marginal flooding apply when:
- we have impair hydrodynamic communication with
external reservoir zone;
- we should develop smaller deposits width not more than
4-5 km;
- we need to intensify the operation.
This flooding is used for fields, layers what have high
permeability and low viscosity of oil. Marginal flooding is the
least intensive type of inside contour flooding and it is the kind of
transition between the edge flooding and inside contour flooding.

3

1
/

2
4

Figure 4.3 – Marginal water flooding: 1 – external oil-
bearing contour (external WOC); 2 – internal oil-bearing contour
(internal WOC); 3 – injection wells; 4 – producing wells

These results edge flooding and marginal flooding caused
further improvement and development of oil fields led to the
feasibility of using inside contour flooding.

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