Synthesis and Study on Hectorite Viscosifier Used in Water Base Drilling Fluid

Hectorite can be used as a high temperature viscosifier in water base drilling fluids, and it is a rare mineral found in nature. A hectorite has been successfully synthesized in laboratory using microwave irradiation method and characterized with XRD, FTIR and particle size distribution analysis. The performance of the synthesized hectorite in water base drilling fluid has been evaluated. The particle sizes of the synthesized hectorite falls in the range between 18.17 nm and 58.77 nm, averaged at 29.72 nm. 4% bentonite slurry treated with 0.3%-1.5% synthesized hectorite, has viscosity, gel strength and YP/PV ratio remarkably increased, and filter loss reduced. When the concentration of hectorite is 1.2%, the viscosity of the slurry is increased by 2.64 times, while the gel strength and YP/PV ratio still remains moderate. The bentonite slurry treated with 1.5% hectorite can resist the contamination of calcium (2.5%) and salt (15%). With temperatures increased from 80℃ to 220℃, the apparent viscosity of the 4% bentonite slurry +1.5% hectorite decreases followed by an increase, and finally remains at above 20 mPa·s. The gel strength and YP/PV ratio changes at a same pattern as that of apparent viscosity, but with remarkable decreases at first. At 200℃, almost all conventional polymers lose their efficiency as viscosifiers in water base drilling fluid, while hectorite is still functioning. Thus the synthesized hectorite is an ideal viscosifier for use in high temperature water base drilling fluid, and is well compatible with other additives.