New viscosity measurements of three natural gas-like mixtures with compositions resembling those of the Qatari North Field reservoir are reported in this work. The viscosity measurements were performed with an electromagnetic piston viscometer for temperatures from (250 to 450) K and pressure between (10 and 65) MPa. The apparatus was calibrated by use of nitrogen and propane as viscosity reference data. Uncertainties of reported data are +/- 2.5 % for pressure less than 30 MPa and +/- 4 % for higher pressures. The predictive ability of several models was analyzed in relation to the experimental reported viscosity data, leading to large deviations from the reported measurements. The effects of mixtures' composition on viscosity were also studied.