Thermoresponsive Bentonite for Water-Based Drilling Fluids

Area of Science:

• Materials Science
• Chemical Engineering
• Petroleum Engineering

Background:

• Bentonite is crucial for drilling fluids, forming mud cakes to protect boreholes.
• Conventional mud cakes are porous and ineffective at reducing high-temperature fluid filtration.
• Developing temperature-responsive materials is key to enhancing drilling fluid performance.

Purpose of the Study:

• To create a thermo-responsive bentonite composite by incorporating N-isopropylacrylamide (NIPAM) monomers.
• To investigate the interaction between NIPAM and bentonite and the composite's thermal behavior.
• To evaluate the performance of a drilling fluid formulated with the modified bentonite for high-temperature applications.

Main Methods:

• Fourier infrared spectroscopy (FTIR), isothermal adsorption, and X-ray diffraction (XRD) to study NIPAM-bentonite interactions.
• Preparation of mud cakes using the NIPAM-bentonite composite, low-viscosity polyanionic cellulose (Lv-PAC), and potassium peroxydisulfate (KPS).
• Environmental scanning electron microscopy (ESEM), contact angle testing, filtration experiments, and shale linear expansion tests to assess mud cake performance at various temperatures.

Main Results:

• NIPAM monomers chemically adsorb onto bentonite, following the D-R model.
• The composite releases adsorbed water above 70 °C, enhancing plugging.
• The mud cake exhibits self-recovery plugging and high resistance at 110 °C.
• Drilling fluid rheology remains stable between 70-110 °C.
• A high-density drilling fluid (2.0 g/cm³) using the composite reduced shale hydration expansion by half at 110 °C compared to conventional bentonite fluids.

Conclusions:

• The thermo-responsive NIPAM-bentonite composite offers self-recovery plugging and stable rheology at high temperatures.
• This modified bentonite is effective in high-density drilling fluids for mitigating shale hydration in high-temperature formations.
• The developed material significantly enhances borehole stability and drilling efficiency in challenging environments.