Abstract
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•Dendrimer polyvinylpyrrolidone grafted on carbon was synthesized as shale inhibitor.•It was evaluated for well shale inhibition with excellent performance.•Active groups bind to the clay surface by H bonding and carbon plug clay pores.
Shale hydration is a major hurdle in oil well drilling with water-based drilling fluids (WBDFs) in oil and gas which could greatly increase the gross cost of production due to well collapse. Shale hydration inhibitors must be added to the WBDFs to prevent such occurrence. Attention has been drawn currently to the design of eco-friendly and low-cost shale inhibitors having excellent compatibility with WBDFs for effective wellbore drilling operations. Herein we report the efficient enhancement of shale inhibition of polyvinylpyrrolidone (PVP) by incorporating activated carbon modified dendrimer (ACD) represented as ACD/PVP with a low environmental footprint. The characterization of the composite material, as well as the sodium bentonite (Na-BT) treated with it via various spectroscopic and imaging instruments including FTIR, NMR, TGA, and SEM, was established. The result of the TGA revealed that the materials could withstand high temperatures. SEM images proved that it has the tendency to successfully inhibiting shale swelling. The prepared material shale preventive ability was further assessed through an anti-swelling ratio, recovery test, and free swelling test. The 2 wt% AC-D/PVP solution reflected outstanding shale inhibition and tolerance to high temperature. This could be ascribed to the synergetic activity of the composite in which the dendrimer acted as a cation, which brings the clay silica sheets together while the PVP participated in sealing the surface of the clay mineral via the large volume of hydrogen bond formation with the dendrimer to form a shield against water penetration. The plugging potential of AC and the hydrophobic character of the PVP polymer chain also contributed greatly to this effect. The PVP which is the major component of the materials is environmentally compatible likewise the AC-D to some extent. In view of this, the AC-D/PVP composite could be a suitable substitute for the present less efficient and unsustainable shale inhibitors that are being used in the oil and gas industry.