Salih M. Awadh, Abdullah A. Al-Yaseri and Ali R. Hussein
الملخص الانجليزي
This research involves the study of permeability declination as a result of
kaolinite due to the changing in pH in the Zubair reservoir (Lower Cretaceous)
during the secondary production by water injection method. Four wells and six core
samples within the North Rumaila field are studied, Minerals have been diagnosed
by XRD and this specific site of clay minerals was diagnosed within the core
samples by scanning electron microscopy (SEM). The core samples are also studied
petrogrphically using the polarizing microscope and found that they mainly consist
of quartz, while the predominant clay is kaolinite. The effect of pH on the values of
permeability was examined through a series of laboratory experiments, as it has
been tested in the cases of gradual sudden increase form acidic to alkaline.
Petrophysical properties (porosity and initial permeability) were measured a prior to
testing. After performing these tests, the final permeability was also measured as
well as the rate of formation damage. The final permeability decreased gradually at a
rate of 20-30% M Darcy during the injection out with solution of pH 3 to 11 with
getting formation damage up to 25%. While in the case injection with sudden
increase pH from acid to alkaline directly, there has been a rapid and substantial
reduction in the final permeability as average of 28% -72%, with a formation
damaged rate of 44%. The results confirmed that the reason of the decrease in the
permeability is due to the kaolinite mineral which is subject to the dispersion
phenomenon during the change in pH, and the acidic environment is suitable for the
reservoir, and does not lead to a reduction in permeability
صالح محمد عوض | Salih Muhammad Awadh | 11028