Investigation of the performance of silica nanoparticles in increasing the strength of a polymer gel prepared by polyacrylamide in oil well condition

In general, temporary well plugging is essential for repairing of oil and gas wells due to their long life time. One of the newest methods used for this purpose is gel polymer plugging. The strength of the gel in the well conditions is one of the most important challenges in the application of gel polymer in the temporary well plugging in work over operation. In this study, silica nanoparticles were used to improve the strength of polymer hydrogels. The bottle and rheological tests were used to determine the gel strength in desired well conditions (high temperature and high salinity). Also, the gel strength properties and swelling behavior were studied in various conditions such as distilled water, formation water, tap water and oil. It was observed that the strength of the gel increased from 520Pa to about 36kPa (5000% increase) by adding nanoparticles. Also, the gel swelling in the aqueous solution has been significantly reduced. Based on the results obtained in this study, a polymer gel containing 9 wt.% of silica nanoparticles with structural strength and thermal stability at 90 °C was introduced for field studies.