Swelling and Deswelling Kinetics of Superabsorbent Polymer

Abstract

In the oil industry, techniques that decrease unwanted water production have drawn large amounts of interest from many companies. During water injection operations, water is injected into the reservoir in order to extract oil remaining in the formation. Due to the heterogeneity in the reservoir formation, oil production will decline and water production will increase as the injected water sweeps the high permeability zones. In order to flush out the oil remaining in the low permeability zones, many treatments have been used. One such treatment involves the injection of a superabsorbent polymer (SAP) into the high permeability zones. The swelled polymer will decrease heterogeneity in the reservoir’s permeability, thus forcing injected water into the oil rich, unswept zones/areas of the formation. Proper application of an SAP can have a dramatic impact on both the production and lifespan of mature oil wells. Understanding the swelling and deswelling kinetics of the SAP is crucial to its application. The following work focused on the use of AT-O3S polymer, a Sodium salt of crosslinked polyacrylic acid purchased from Emerging Technologies®. The polymer had a particle size of 35 to 60 meshes, or 250 to 500 microns. The swelling and deswelling ratio of such a polymer is heavily influenced by salinity, temperature, and pH. In order to study the polymer’s kinetics, 1% (for swelling) or 0.1% (for deswelling) by solution weight of polymer was allowed to swell and deswell over time in various brines. These brines were made up of deionized water, 1% to 20% (by wt.) Sodium Chloride, and/or 1% to 10% (by wt.) Calcium Chloride. The effect of temperature on the final swelling ratio was afterwards tested. Understanding the reaction of SAPs to conditions similar to those found in an oil formation can help the oil industry to utilize this tool with greater efficiency.