Study on Rheological Properties for Modified-natural-macromolecule Drilling Fluids

Studying rheological properties of the additives and system would help further study and application of the modified-natural-macromolecular drilling fluids. The suspending fluid mixed with modified-natural-macromolecular additives (IND30, NAT20, NFA25) and 4% bentonite fluid were experimentally detected. The tests included shearing force on 6 shear rates of 1022, 511,340.7,170.3, 10.22 and 5.11s-1 as well as the shearing force of drilling fluid system at the condition as stated. The rheologic properties and flow curves were found. The rheological properties of suspending fluid with dosage 0.2% IND30 are similar to Bingham model. The rheological properties of suspending fluid with dosage 0.3% IND30 are similar to Power model. The rheological properties of suspending fluids with addition 3 NAT20 are similar to Power model. The rheological properties of suspending fluids with dosage 6% NFA25 are similar to Bingham model. The rheological properties of drilling fluids prepared with 12 formulae according to orthorhombic designed formulations are all similar to the Power mode.