Polyurethanes are special nonionic polymers which had a wide range of applications nowadays. This work aims to produce 
different nonionic polyurethanes by the reaction of polyethylene glycols with different molecular weights (4000, 6000, 
10.000, and 20.000 g/mole) and toluene diisocyanate. The obtained polyurethanes' structures were determined using 
molecular weight measurements, Fourier transform infrared spectroscopy (FTIR), and proton nuclear magnetic resonance (1H￾NMR). The effect of the synthesized polyurethanes on the rheological properties of two drilling fluids was studied. The 
polyurethane polymers were influenced by the filtrate loss of the drilling fluids in comparison to the blank. The results 
showed that the synthesized polyurethane nonionic derivatives effectively enhanced the shear-thinning non-newtonian drilling 
fluids following the modified power Law Model (Herschel Bulky Model). The other rheological properties of the formulated 
drilling water-base muds, including apparent viscosity (AV), plastic viscosity (PV), yield point (YP), and gel strength were 
improved considerably compared to the commercial formulation.