Influence of ZnO-Decorated Multi-Walled Carbon Nanotubes and Pure-Bore Biopolymers on Shale Chemical Stability and...

The present work examines the fluid loss volume (FLV) and shale swelling behavior of water-based mud (WBM) modified with a hydrothermally synthesized Zinc Oxide/Multiwalled Carbon Nanotubes (Zn-COM) nanocomposite and a Bio-Poly-(Pure bore). A central composite design methodology (CCD) was employed to systematically evaluate the influence of these additives' concentration on the FLV and shale swelling. The most problematic shale formation (Ranikot) was analyzed in this study. A total of 13 experimental runs were investigated in this article. The result of the study reveals that the nanocomposite material, with its high aspect ratio, penetrates and seals both micro- and Nanopores' spacing, ultimately creating a robust bridging network. A substantial reduction in FLV from 26.0 to 6.5 mL was recorded as the concentration of the nanocomposite material increased to 4.154 g. However, the concentration of Bio-Poly does not have a significant impact on the FLV reduction. The oversaturation of Bio-Poly causes polymer chain entanglement and coagulation, which reduces the uniform dispersion of both entities. For the shale swelling, as the loading of Zn-COM increases in WBM, the shale swelling drastically reduces. The swelling dropped to 5.8% from 17.2% as the weight of the nanocomposite increased to 4.154 g. The nanocomposite material predominantly suppresses the osmotic diffusion and minimizes the water ingress into the shale sample. On the other hand, this suppression was not substantial with Bio-Poly concentration, and high swelling percentages were reflected with high Bio-Poly concentration and low Zn-COM loading. Analysis of Variance supported all the findings, with the nanocomposite demonstrating a strong statistical significance of p < 0.05 for both FLV and shale swelling. This statistical measurement confirms the effectiveness of Zn-COM in sealing the pores and in suppressing the shale hydration.