Siree Nasakul's dissertation
by
Siree Nasakul, Ph.D.
University of Texas at Austin, 2000
Supervisor: Dr. M.M. Sharma
Polymer gels have been extensively used in oil and gas wells. In this
dissertation we explore the use of novel thermoreversible gels and
temperature triggered kinetically controlled gels for application in
water shutoff, gravel packing and fracturing. Thermoreversible gels
consisting of block copolymer surfactants have the unique property of
forming a gel between a certain temperature range. The range of gelation
temperatures can be controlled by varying the surfactant concentration,
molecular weight, hydrophobicity and functional groups. The gelation is
reversible and both the lower and upper gelation temperatures are sharp
phase transitions. Gelation and rheological properties of a range of
Pluronic and Tetronic surfactants are investigated. Core flow
experiments are conducted to show that gels can be used to reversibly
reduce the permeability of cores. The gels will find likely applications
in fracturing and gravel packing.
Temperature triggered kinetically controlled gels have been synthesized
primarily from crosslinked functionalized PEGs and Pluronics. The
gelation times and gel properties can be varied based on the molecular
weight, functional groups, and degree of crosslinking of gels
synthesized. Gelation kinetics are controlled by monomer concentration,
monomer type, initiator concentration, initiator type, pH and
temperature. Some gels formed are found to be hard and swell in the
presence of water to several times their weights as well as being stable
for extended period of time. Such gels will find applications in water
shutoff treatments. Other gel systems have been formulated to degrade
rapidly with time. The swelling and degelation of such gels
have been investigated in detail.
It is found that the use of crosslinked PEGs and Pluronics provide a
family of gels that will find likely application in water shutoff
treatments. Thermoreversible gels such as those from Pluronics and
Tetronics can find applications in fracturing and gravel packing
applications. Core flow experiments performed to evaluate these gels at
reservoir conditions indicate the suitability of these gel systems for
these applications.
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