Polynapthalene Sulfonate Superplasticizer for Oil well Cementing: Effect on Compressive Strength

A superplasticizer or dispersant acts as a friction reducer to enhance the rheological properties of cement slurry, thereby eliminating the need for high pump pressure to pump the viscous slurry behind the casing. Polynaphthalene sulfonate (PNS) is a common dispersant for well cement; however, with the emergence of geopolymer technology for oil wells, the application of PNS in the industry has yet to be investigated. The focus of the research is to examine the influences of PNS on the early, medium, and final compressive strength of geopolymer cement cured at 3000 psi and 100 °C with PNS concentration ranging from 0.0 to 2.0 by weight of fly ash (bwof %). The findings show that PNS can increase the 8-hour compressive strength of geopolymer cement, but it can decrease the 24-hour compressive strength. However, only the sample with the highest concentration of PNS exhibits better compressive strength than the control sample at 48 hours. Additionally, the results demonstrate that the compressive strength of geopolymer cement with PNS increases with a longer curing duration. It is advisable to run a prediction plot to determine the optimum concentration that can result in high compressive strength for 8, 24 and 48 hours.