Optimization of graphene-enhanced geopolymer cement for oil well applications

Geopolymer cement is a viable and sustainable replacement for conventional Portland cement, drawing attention for its enhanced durability and reduced shrinkage when compared to API Class G cement, alongside its potential to reduce CO₂ emissions. This research aims to develop fly ash-based geopolymer cement incorporating graphene oxide (GO) under high pressure high temperature (HPHT) conditions for oil well cementing application. The investigation unfolds in three distinct phases to meet its objectives. Phase 1 identifies the optimal GO concentration, demonstrating that a formulation with 3.83 M NaOH and 0.2% GO achieves a compressive strength of 21.39 MPa. Phase 2 applies this optimal formulation (Formulation OP 1) in functional oil well cementing tests, with rheology showing stable viscosity across temperatures and a thickening time of 3:25 hr at 100 Bc. Phase 3 evaluates compressive strength under varying temperature and pressure, revealing a maximum compressive strength of 25.68 MPa curing at 120°C and 20.68 MPa. Results show that higher temperatures enhance compressive strength, attributed to accelerated geopolymerization and improved pore structure. Experimental validation aligns closely with predictions, with deviations within 7.2%. This study highlights geopolymer cement's capability as a sustainable, high-performance option for challenging oil well settings, presenting a significant advancement over traditional oil well cement solutions.