Development and Performance Assessment of Sulfonated Lignin Nanoparticles as a Bio-Based Retarder for High-Temperature Oil Well Cementing

Abstract

Conventional cement retarders tend to raise slurry viscosity, impair pumpability, reduce compressive strength, and shorten effective thickening time, thereby complicating cement placement in deep wells. In this study, sulfonated lignin nanoparticles (SLNPs) derived from empty fruit bunch (EFB) biomass were developed as a novel bio-based retarder to improve cement performance under harsh wellbore conditions. The lignin nanoparticles were subsequently sulfonated to enhance their solubility, dispersion stability, and adsorption capacity, thereby improving retarding efficiency and interaction with cement hydration products. The morphology and thermal stability of the SLNPs were characterized using field-emission scanning electron microscopy (FESEM) and thermogravimetric analysis (TGA). The synthesis process produced well-dispersed SLNPs with an average particle diameter of approximately 24 nm, indicating effective nanoscale modification of lignin. The compressive strength performance of SLNP-modified cement systems was systematically evaluated and compared with that of a commercial retarder, sodium borate. Experimental results demonstrated that SLNP-modified cement maintained structural integrity and mechanical stability up to 250 °C. After 28 days of curing at 250 °C, the SLNP-modified cement achieved a compressive strength of 68.65 N/mm2, which was significantly higher than that of the sodium borate-retarded cement (46.03 N/mm2). HPHT thickening-time analysis showed that increasing SLNP concentration progressively extended the thickening time (TT100) from 263 min for the control slurry to 540 min at 0.8 wt.% SLNP, providing an extended placement window without abnormal gelation or consistency bulging. Rheological measurements revealed only moderate increases in plastic viscosity (72–101 cP) and yield point (28–42 lb/100 ft2), indicating that retardation was achieved without compromising slurry pumpability or suspension stability. Overall, the results demonstrate that EFB-derived SLNPs provide an effective balance between hydration control, thermal stability, mechanical strength, and slurry flowability under HPHT conditions. Therefore, SLNPs represent a promising and environmentally sustainable alternative to conventional retarders for deep- and ultra-deep-well cementing applications.