Rasim Serdar Rodoplu's thesis
by
Rasim Serdar Rodoplu, MSE
University of Texas at Austin, 2002
Supervisor: A. Daniel Hill
Matrix acidizing is a commonly used well stimulation technique to enhance production of
reservoir fluids by recovering formation permeability in the near wellbore region. This
thesis is a comprehensive study on sandstone acidizing in which damaging minerals in the
formation are dissolved by injecting an acid into the impaired well below the fracturing
pressure.
The sandstone acidizing process is investigated thoroughly from its theory to the design
concepts. In sandstone acidizing design, to predict skin change as a function of acid
injection volume is the main goal. Skin is calculated from permeability, therefore accurate
prediction of permeability plays a critical role in acidizing. Up to now, empirical
correlations have been used to determine permeability variation. This method was based on
simply relating permeability to porosity change without considering the to affect of any
other parameters such as physical or statistical properties of the medium during acidizing.
A more realistic approach is to allow all these parameters effect the permeability as they
possibly can. Such an approach has been accomplished by modifying a single-phase
permeability model, which was presented by Panda and Lake (1995).
The objective of this study is to apply and validate a rigorous permeability model to
the two acid, three mineral model of sandstone acidizing which is commonly used to model
the changing mineral fractions and porosity during acidizing. Panda and Lake's model is
chosen to predict permeability response during sandstone acidizing process because it
gives a more complete representation of the flow conductivity of a consolidated permeable
medium by using all the relevant permeable medium properties. The permeability model has
been modified to be compatible with the two-acid, three-mineral model and incorporated
into the UTMAST, an acidizing simulator to perform numerous simulations.
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