The depletion of conventional hydrocarbon reserves, coupled with increasing global energy demand, has driven the petroleum industry to pursue deeper and more complex reservoirs characterized by high-pressure, high-temperature (HPHT) conditions. These environments, particularly in carbonate formations prevalent in Mediterranean regions, present unique challenges that require innovative approaches to drilling fluid formulations and wellbore operations. This study provides a comprehensive investigation into advanced solutions aimed at enhancing the efficiency, safety, and sustainability of drilling practices in such demanding settings.

Central to this research is the development of water-based drilling fluids augmented with nanoparticle bio-polymer additives, specifically Poly-Anionic-Cellulose (PAC) and Carboxyl-Methyl-Cellulose (CMC), to improve rheological performance and fluid loss control. Extensive experimental analyses reveal that these additives significantly enhance the thermal stability and fluid loss characteristics of bentonite-based formulations while maintaining predictable rheological behavior consistent with models like Bingham and Herschel-Bulkley. These advancements enable drilling fluids to perform reliably under extreme HPHT conditions, offering a robust solution to the operational challenges associated with carbonate reservoirs.

The study also delves into critical wellbore stability measures, underscoring the importance of precise casing design and cementing strategies. Determining optimal casing depths, adjusting mud weights to manage formation pressures, and analyzing burst, collapse, pore, and fracture pressure relationships are highlighted as pivotal in mitigating risks such as kicks, blowouts, and circulation losses. Effective cementing practices, supported by tailored slurry formulations and optimized equipment performance, ensure wellbore integrity while reducing the risk of formation damage or fluid migration.

By integrating cutting-edge materials with strategic operational methodologies, this research establishes a forward-looking framework for addressing the technical, economic, and environmental challenges of modern drilling operations. The findings contribute to advancing drilling efficiency and safety, paving the way for sustainable exploration of complex reservoirs. This holistic approach offers significant implications for the future of the petroleum industry, particularly in HPHT settings where innovation has become imperative.