Development of new smart drilling fluids using nano-materials for unconventional reservoirs

Drilling fluids used for accessing unconventional reservoirs need new focus because the fluids used to exploit conventional reservoirs need without some modifications or new formulations. New smart-fluid formulations were developed and optimized using nano-materials. Three nano-materials were added to the generic water-based fluids. Scanning electronic microscope tests were performed to check the size quality of the nano-materials. Rheology properties, pH and filtration tests were performed to evaluate the smart drilling fluids. Mud cakes formed by each smart drilling fluid were collected and scanned. For practical field applications, the smart drilling fluids were tested against two rock samples by performing dispersion, barite sag and aging (stability) tests. The rocks were characterized using scanning electronic microscope (SEM), cation exchange capacity (CEC) and adsorption tests. Results showed that the developed fluids exhibited excellent rheological properties and the filtration losses were reduced after adding nano-materials. Mud cakes formed by each smart drilling fluid were collected and scanned. Thin, tight, and well textured mud cakes were formed. The mud cakes' thicknesses were reduced significantly after adding nano materials. The barite sag tests indicated the fluids to be excellent for cutting suspension. No sedimentation was observed after aging for three days, which indicated a good cleaning and suspension of drilled cuttings. The rheology and filtration properties of smart drilling fluid system remained stable under static condition after three days of aging. Results showed reduced shale dispersion, excellent suspension capacity, and stability. The cost comparison between the developed smart drilling fluids with nano-materials and base (generic) drilling fluids shows that that the smart fluids are relatively inexpensive even though they are excellent for preventing wellbore instability and for used in the environmentally sensitive areas.