Rheology of Triamine Functionalized Silica Reinforced Polymeric Gels Developed for Conformance Control Applications

Abstract

Recently, cross-linked polymers such as polyacrylamide (PAM)/polyethylenimine (PEI) have been used in conformance control applications to replace conventional lost circulation materials (LCMs). The objective of this work is to introduce functionalized silica to reinforce PAM and enhance gel performance under high temperature high pressure (HTHP) conditions. A system was developed using PAM/triamine silica (TAS) combined with nanosilica (NS) to replace the conventional PEI as a cross-linker. Polymer systems consisting of 9 wt % PAM and polyacrylamide tert-butyl (PAtBA) with various concentrations of PEI, TAS, and NS (50 nm) were used to produce mature gels at 130 �C. The results have shown that TAS has formed a gel with code "E" on the Sydansk coding system. Adding a low concentration (1-2 wt %) of 50 nm silica has eliminated the settling of microsized TAS and produced a reinforced gelant system with code "I". The cross-linking was accomplished via an amine group similar to the PEI mechanism with the advantage of strength and stability due to the presence of silica. The increase in the gel strength of the PAM/TAS formulation depends on the amount of NS; the gel strength of the PAM/PEI system has increased from 1670 Pa to more than 9000 Pa for the PAM/TAS/NS system. The new formulation is compatible with high salinity water, and a chelating agent could be introduced to prevent formation damage.