Page 230 - Formation Damage during Improved Oil Recovery Fundamentals and Applications

204 Bin Yuan and Rouzbeh G. Moghanloo

Figure 4.15 Variation of maximum retention concentration of fine particles in a
radial flow system (Yuan and Moghanloo, 2018a).

migration and their size exclusion effects can also result in severe damage
to reservoir permeability, which leads to the decline of well injectivity (or
productivity in case of production wells). Therefore, a better understand-
ing of avoiding versus encouraging fines migration in reservoirs is
required. Fig. 4.15 presents the variation of maximum retention concen-
tration of fine particles with the increase of distance away from an injec-
tion well. Within the near-wellbore region (less than about x D 5 0.2), the
large flowing velocity exaggerates the problem of fines detachment and
straining, and the blockage of the detached fine particles into pore-throats
leads to significant loss of injection pressure. However, in the regions
remote from the wellbore with slow flowing rates, even with changes to
water saturation, very small reduction of fines retention concentration
leads to negligible problems of fines detachment and associated formation
damage.
Therefore, evoking the debate between the pros and cons of fines
migration, it is desirable to control fines migration to take advantages of
its positive effects far from the wellbore but minimize its weaknesses of
inducing formation damage near the wellbore. This section develops the
mathematical foundation for designing a nanofluid-slug pre-flush (treat-
ment radiuses 5 0.05, 0.10, and 0.25) to enhance well injectivity while