Synergistic Physicochemical Inhibition of Reactive Shale Formations Using Hydrothermally Synthesized Hydroxyapatite Nickel Tungstate Nanocomposites in Water‐Based Drilling Fluids

ABSTRACT Wellbore instability driven by the volumetric expansion of reactive shale formations remains a primary operational challenge in modern drilling engineering, causing severe mechanical failures and substantial economic deficits. The objective of this study is to formulate and evaluate a novel dual‐action chemical additive capable of simultaneously neutralizing clay surface charges and physically sealing nanometer‐scale pore throats to completely suppress subterranean hydration. To solve this critical problem, a bespoke nanocomposite comprising hydroxyapatite and nickel tungstate was synthesized via a highly controlled wet chemical coprecipitation methodology. The physicochemical architecture and crystallographic properties of the active nanoparticles were thoroughly characterized using advanced spectroscopic techniques, whereas the macroscopic inhibition efficiency was systematically quantified through dynamic linear swelling fluid loss evaluation, static sedimentation, and rigorous hot rolling recovery tests using premium‐grade bentonite and reactive shale cuttings. The experimental results conclusively identified an optimal solid concentration of 1000 ppm, which delivered extraordinary performance by restricting linear clay swelling to a mere 30% and achieving a near‐perfect shale recovery rate of 93% under aggressive thermomechanical conditions. At this mathematically precise dosage, the multivalent cations effectively displaced native sodium ions while the meticulously calibrated nanoscale dimensions mechanically plugged exposed microfractures, completely preventing internal water ingress. Furthermore, the structural incorporation of the nanoparticles into heavily weighted and highly polymeric field representative mud systems maintained absolute rheological stability while actively reducing high‐pressure filtration volumes. Ultimately, the synthesized hybrid nanomaterial functions as a highly versatile and profoundly effective stabilizing agent, offering a transformative chemical solution for safely navigating highly reactive geological formations without compromising the delicate hydraulic balance of the primary host fluid.