Page 162 - Formation Damage during Improved Oil Recovery Fundamentals and Applications

140 Thomas Russell et al.

This field was operated at the time the data were recorded by Exxon.
Seawater was used as the injection fluid; however, it contained a lower
salt concentration due to fresh water discharge from the Mississippi River.
Coreflooding experiments using seawater showed significant permeability
decline and the presence of suspended fines in the effluent indicating that
permeability decline was due to fines migration. Qualitative analysis indi-
cated that all intervals with permeability lower than 500 mD and clay
content higher than 5% would experience significant permeability decline
(Ogletree and Overly, 1977).
The Pervomaiskoye Oil Field in Republic of Tatarstan is another
example of injectivity decline due to low-salinity waterflooding
(Fig. 3.24C). Water was taken from the Kama River, which was the near-
est water source. After 40 years of waterflooding and about two PVI
injected, 30.1% of the injected water was low-salinity. High-salinity
water, which was the formation water, had about 252,738 ppm of salt,
while low-salinity water from the river had 848 ppm of salt.
Coreflooding experiments showed fines release and formation damage
when reducing water salinity (Akhmetgareev and Khisamov, 2015).
In all three field cases, the model was capable of reproducing the
impedance growth caused by detachment and migration of fines lifted by
2
low-salinity water injection. The obtained parameters and the R coeffi-
cients are presented in Table 3.9.

3.6 EFFECTS OF NONEQUILIBRIUM/DELAY IN PARTICLE
DETACHMENT ON FINES MIGRATION

In all previous discussions on particle detachment, changes to fluid
properties were assumed to have an immediate effect on the detachment

Table 3.9 Tuning the fines-migration parameters (drift delay factor α, filtration
coefficient λ, and formation damage coefficient β) from data collected from three oil
fields subjected to low-salinity waterflooding
Field α λ (1/m) β R 2
Ventura Oil Field 2.7 3 10 27 18.08 177.9 0.86
West Delta Block 73 1.4 3 10 27 95.89 75190 0.66
Pervomaiskoye Oil Field 3.4 3 10 27 57.58 3316 0.78