Page 47 - Formation Damage during Improved Oil Recovery Fundamentals and Applications

Low-Salinity Water Flooding: from Novel to Mature Technology 29

simulation, involving two-phase immiscible compressible flow with a
maximum particle retention function, fresh water was injected, into a
watered-out production well, over a limited period to form a barrier fluid
to decrease water encroachment up-dip into a gas reservoir with a strong
water drive during the pressure-blowdown production phase (Fig. 2.4).
The induced fines migration (pore plugging) formation damage was
localized to the vicinity of the injection well. The impact is to reduce the
phase permeability for water, but with very minor impacts on gas-phase
permeability.
This techniqueleads,inthe simulationatleast,toadecrease in
up-dip water cut, and prolonged the life of up-dip gas production wells,
thereby increasing gas recovery by 15 18%. The volume of LSW
injected should be carefully balanced to suit the reservoir characteristics
and scale; too large a volume was found to increase water cut and
decreased incremental gas recovery water. It was found for the gas
reservoirs simulated that injecting banks of LSW of about 1.5 3% of
the total reservoir pore volume, and then halting LSWF (after about
1.5 to 3 weeks in the reservoir volumes evaluated), lead to optimum
gas recovery.

Figure 2.4 Schematic illustrating the potential of LSWF-induced fines migration to
increase gas recovery by inhibiting water encroachment by targeted reduction in
permeability in watered-out leg of a reservoir. Modified after Nguyen et al. (2013).