Polymer gel systems

CappeUo J., Crissman J.W., Crissman M., Ferrari F.A., Textor G., WaUis O., Whitledge J.R., Zhou X., Butman D., Auketman L., and Stedronsky E.R. In-situ self-assembling protein polymer gel systems for administration, deUvety, and release of drugs, J. Contr. Rel., 53, 105, 1998. 

Dovan, H.T. Hutchins, R.D. "Development of a New Aluminum-Polymer Gel System for Permeability Adjustment," SPE/DOE Paper 12641, 1984 SPE/DOE Fourth Symposium on Enhanced Oil Recovery, Tulsa, April 15-18. 

Characterization of Rheological Properties of Mixed-Polymer Gel Systems... 

As described above, polymer gel systems composed of the network polymer and solvent are a special state. The solution NMR techniques are available to characterize the solvent contained in the gels, but not to the network polymer. We cannot obtain reasonable NMR signals with high intensities, S/N ratio and resolution for gel samples by solution techniques. This is caused by the restraint of motion, the strong dipole-dipole interactions, the chemical shift anisotropy and their long Ti and short T2 values. 

High resolution solid-state NMR techniques are powerful means for characterizing the network polymer of polymer gel systems. They give useful information on the network polymer. The function of this chapter is to review the researches on synthesized polymer gels by high resolution solid-state NMR techniques. The research on polymer gels composed of natural materials, such as proteins and polysaccharides, are reviewed in other chapters. 

The T2 values for the network polymers of gel are generally very short and the motion of main chains especially lies in the slow motion region of the BPP theory of NMR relaxation [12]. In this region, the T2 value is shown to be almost constant. Therefore, the Ti measurements are performed in general to get information on the motion of polymer gel systems. 

The sequence in the treatment of a core with a polymer gel system is similar to that just described and typically involves three steps. First, the initial permeability of the core sample is measured with brine. Then the core is treated with a polymer/crosslinker solution at a constant rate using a dual piston HPLC pump and a transfer cell (see Figure 5) while monitoring pressure with a differential pressure transducer. The core effluent is fractionated for analysis. This includes the determination of polymer and crosslinker concentration, the measurement of sample gelation tendencies, and the investigation of rock/polymer interactions. Finally, after a waiting period to allow gelation, the final permeability of the core is measured with brine to evaluate the effectiveness of the treatment. 

It is important to note that the proper evaluation of a polymer gel system must also include the evaluation of the polymer in addition to the gel system. Otherwise, it is not possible to differentiate whether the permeability reduction is due to the polymer alone or gel formation. 

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