Formulation and characterization of water-based drilling fluids for gas hydrate reservoirs with efficient inhibition properties

Natural gas hydrates are presently considered as a potential source of future energy as it is widely distributed along the continental margins and in the permafrost areas. However, the drilling operation through such hydrate-bearing formation is quite risky because of unconsolidated formation, fragile nature of formation and uncontrolled dissociation of hydrate during drilling. In this study, an attempt was made to overcome the issues by a specially designed nanoparticle-enhanced water-based drilling fluid for its potential application in hydrate reservoirs. The rheological properties of different water-based drilling fluids, formulated by bentonite, carboxymethyl cellulose (CMC), SiO2 nanoparticle, barite and salts were studied both at high pressure and low temperature condition. Results show that the rheological properties, such as plastic viscosity, apparent viscosity, gel strength, yield point are highly promising. It has been found that silica nanoparticles and CMC reduce the fluid loss properties but CMC has a greater effect on fluid loss than silica nanoparticles. Zeta potential value of the formulated drilling fluids indicates their higher stability and strong function of the used nanoparticle. Inhibition effect of drilling fluid on hydrate formation was evaluated by using the drilling fluid with an optimized formulation in an autoclave hydrate cell at high pressure and low temperature. The experimental results reveal that the designed drilling fluid shows excellent inhibition effects on hydrate formation. This happens because of excellent thermodynamic and kinetic inhibition effects of CMC, salts and SiO2 nanoparticles. [GRAPHICS] . HIGHLIGHTS 1. Nanoparticle and polymer-based efficient drilling fluids for gas hydrate reservoir. 2. CMC and SiO2 nanoparticle enhance the performance of water-based drilling fluid. 3. Flow curves of different drilling fluids indicate Non-Newtonian flow behavior. 4. Filtration loss decreases with increasing concentration of CMC and nanoparticles. 5. Improved hydrate inhibition effects by using thermodynamic and kinetic inhibitors.