Consolidation of carbonates using hydrolysed polyacrylamide: Effect of temperature, pressure, salinity, and nanoparticle crosslinking

This paper discusses a comprehensive three-part experimental study on the consolidation of calcium carbonate (CaCO 3 ) via hydrolysed polyacrylamide (HPAM). The first part involves the consolidation ability of HPAM on CaCO 3 investigated under room conditions. The setups in this work are dilute (1:25 mass ratio of CaCO 3 to HPAM) and concentrated (1:2 mass ratio) colloidal systems, and an incubation of Iceland spar calcite crystal in dilute HPAM solution. UV–Vis absorption, zeta potential, oscillatory rheology in the form of storage modulus (G’), unconfined compression stress (UCS), and atomic force microscopy (AFM) force mapping, reveal positive interactions and increased consolidation with higher HPAM dosage, up to an optimum level. The second part explores the impact of reservoir conditions, namely salinity and temperature, on the consolidating ability of HPAM. Salinity tests indicate a higher polymer dosage requirement under increased salt concentration to maintain optimum CaCO 3 consolidation, while temperature tests show a reduction in peak mechanical strength of consolidated CaCO 3 samples. In the final part, the preservation of the effectiveness of deploying HPAM in reservoir conditions by crosslinking it with silica nanoparticles (SiONP) is explored. The results from G′ and UCS analyses demonstrate that CaCO 3 consolidated by crosslinked HPAM retains peak mechanical strength even when treated with brine and subjected to continuous heating for three days. This extensive investigation into the consolidation of CaCO 3 by HPAM provides valuable insights into the potential use of HPAM for strengthening reservoir rocks, with the novel approach of crosslinking showing promise for preserving its usability in challenging reservoir conditions. • HPAM was able to consolidate CaCO 3 under room conditions. • Salt ions caused charge screening of HPAM, leading to coiling. • Heat from high temperature caused thermal scission of HPAM chains. • Crosslinking HPAM with SiONP improved HPAM's thermal and chemical stability.