Admicellar Polymerization to Compatibilize Calcium Carbonate With Oil-Based Drilling Mud

Weighting agents like calcium carbonate (CC) are added to drilling mud to improve mud properties and performance during oil and gas drilling operations. Oil-based mud (OBM), a more preferred drilling mud, being hydrophobic is particularly non-compatible with hydrophilic CC. This work explored an economically viable admicellar polymerization technique to surface-modify the high energy hydrophilic CC surface to a low energy hydrophobic surface by polymerizing organic styrene monomer within an admicelle of nonionic surfactant Triton X-100 adsorbed on the CC surface. BET N2 particle size analysis, Soxhlet extraction of the coated polymer, Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectra analysis, and thermogravimetric analysis (TGA) of the treated CC and polymer extract confirmed the production of a successful thin film polystyrene-coated CC. The coarse CC size grade had the most polymer. Consequently, OBM formulated with the treated CC is expected to; be more homogeneous, achieve higher wellbore pressure, remove drill cuttings better, have a more stable thin film low-permeability filter cake, and exhibit an enhanced overall performance. Pilot mud testing of a surface-modified CC formulated OBM is under way