The article presents an experimental investigation of the rheological properties of carbomer microgels. All of the tested fluids were made up from commercial polyacrylic acid, Carbopol Ultrez 30. In total, eighteen microgels were prepared, differing in concentration; 0.2, 0.4 and 0.6 wt%, with six levels of neutralisation for pH from 4.0 to 9.0. Based on the experimental flow curves it was found that all tested microgels are yield stress shear-thinning fluids. Therefore, the Herschel–Bulkley model was used and its rheological parameters were determined. It was found that both the concentration and the pH value significantly affected the yield stress. As the Carbopol concentration increased, the yield point also increased. With the increasing value of pH, the yield stress first increased until a certain maximum level and then decreased. The maximum values of yield stress were obtained for pH = 6 to 7, depending on polymer concentration. It was also found that flow curves of the tested microgels could be described using one universal master curve, thus they have common rheological behaviour.

In this study some of the experimental results of water shut-off treatments in oil and gas production wells were presented. The effect of water saturation of Miocene rocks of the Carpathian Foredeep on the relative permeability to gas was analyzed. Also, wide review of the worldwide publications from the point of view of the results obtained in water shut-off treatments in oil and gas formation was presented. Based on experimental results efficiency of relative permeability modification of sandstone from Szydłowiec to brine and nitrogen by four selected chemicals polymers and microgels was evaluated. Experimental results indicated that trend changes of permeability modification strongly depends on the fluid used in the RPM treatment. Moreover, efficiency of permeability modification to brine depends on flow rate of brine through the core - the lower brine flow rate the higher efficiency of the RPM treatment. RPM product number 1 caused significant loss of permeability to brine ca. 60% and slight permeability modification to gas ca. 18%. This permeability change to brine and gas was obtained by modification of formation wettability what affects well productivity. In the case of product number 2 which is based on microgels technology, also significant modification of selective permeability to brine was observed. Loss of permeability to brine was in the range of 65 to 90% while to gas ca. 50%.