Enhanced Shale-Swelling Inhibition and Plugging Efficiency in Water-Based Drilling Muds by Graphene Oxide Nanocomposites

Abstract Shale formations pose significant challenges to conventional water-based muds (WBMs) due to fluid invasion, cuttings dispersion, shale hydration and swelling, leading to wellbore instability. To address these challenges, a novel dodecylamine graphene oxide nanocomposite (DAGONC) was synthesized as a shale inhibitor. Its performance in mitigating shale hydration and enhancing the plugging efficiency of WBMs was systematically evaluated through linear swelling, API filtration, uniaxial compressive strength, contact angle, atomic force microscopy (AFM), and BET analyses. The performance of DAGONC was compared with KCl and partially hydrolyzed polyacrylamide (PHPA) inhibitors. FTIR, XRD, and FESEM confirmed successful synthesis and characterization of DAGONC. The linear swelling test showed that 0.5 wt % DAGONC reduced shale swelling to 3.6%, compared to 9.8% and 6.0% for 5 wt % KCl and 5 wt % PHPA, respectively. In addition, shale cuttings recovery at 250 °F reached to 96% with DAGONC, outperforming KCl (84%) and PHPA (90.7%). The findings showed that incorporating DAGONC into WBMs reduced fluid loss by 55% under LPLT conditions and by 38% at HPHT conditions, showing a significant enhancement in filtration control. DAGONCS increased shale surface hydrophobicity, with a contact angle of 85.6°, versus 54.6° and 63.1° for KCl and PHPA, respectively. AFM revealed a thin and homogeneous DAGONC layer bridging pores and cracks, while BET analysis indicated a reduced surface area to 6.63 m2, confirming strong interaction between DAGONC and the shale matrix. The flexible sheet-like structure forms a continuous protective film, effectively sealing pores, inhibiting water invasion, and maintaining shale integrity. These findings suggest that DAGONC can improve WBM performance and contribute to enhanced wellbore stability in shale formations.