In this work, we used a combination of experimental techniques in order to validate pore network modelling' at both Darcy and pore scale. The pore networks were etched on a silicon wafer, and comprised 28202 rectangular capillaries 200 ~m long and 40 ~m deep, with two different capillary width distributions.' Flow experiments were perfonned with water as a model Newtonian fluid and shear-thinning partially hydrolyzed polyacrylamide (HPAM) polymer solution as the model non-Newtonian fluid. An original method was proposed in order to implement in the simulator the Carreau mod~l as the constitutive equation of the . shear-thinning fluid. Darcy scale experiments consiste~. in measuring pressure gradient between pore network inlet and outlet at different constant flow rates. Thus, an 'apparent' rheogram of the fluid was experimentally achieved. Quantitative agreement is seen between the experiments and the network calculations for both Newtonian and shear-thjnning regimes. However, at high ...../. flow rates HPAM exhibit a shear-thickening regime due to elastic effects that are not incorporated in the network model. Microscopic flow behaviour in the capillaries was visualized by using micro particle image velocimetry (~PIV) technology. This enables us to measure the velocity profile in the capillaries ~with a one micron resolution. An original method was developed to allow us to compare the computed mean velocity and the experimentally measured maximum velocity. Good correlations wer'~ found both in Newtonian and shear-thinning regime. Once the HPAM solution enters the shear-thickening regime, there is a marked increase in the amount . , of scatter observed in individual network ducts. More detailed IlP1V measurements of the micro flows in several 'neighboring channels show that asymmetric streamline patterns have been observed indicating that the effects of 'feeder' channels are leading to a very extensive 'inlet effect' as is often observed for extensional flows. The thesis is the first to present such a detailed analysis of both the Darcy scale rheology and the detailed micro-flow field using both experiment (etched silicon micromodels along with ~PIV) and pore scale network modelling. Comparison between experiment and theory shows a very interesting level of agreement.