## 3 Results and Discussion of Conducted Laboratory Research
Figure 11: The friction forces measured on the block made from different materials in tested polymer drilling fluid with weighting additive and with lubricant Y at a concentration of 2% vol. (PWLY2%). Figure 12: The friction forces measured on the block made from different materials in tested polymer drilling fluid without weighting additive and with lubricant Z at a concentration of 2% vol. (PLZ2%). From the measured data shown in Figure 12, the value of the friction force of the test blocks made from PA6, Teflon and POM decreased as the test time progressed. Again, after 15 min of testing, the highest value of the friction force was recorded with the block made from PA6, followed by the test blocks made POM, while the value was the lowest with the test block made of Teflon. The last drilling fluid to test was the polymer fluid with weighting additives in which lubricant \(Z\) was added at a concentration of 2% vol. (PWLZ2%). Figure 13 shows a diagram of the measured friction force for the tested blocks in polymer fluid with weighting additives in which lubricant Y is added at a concentration of 2% vol. From the measured data shown in Figure 13, the value of the friction force of the test blocks made from PA6 showed a slight increase as the test time progressed. For the test block made from POM, the value of the friction force slightly decreased, while for the test block made from Teflon, the friction value did not change. After 15 min of testing, the highest value of the friction force was recorded with the block made from PA6, followed by the test blocks made of POM, while the value was the lowest with the test block made of Teflon. Comparing the values of the friction force for each block tested in both polymer fluids with and without weighting additives in which lubricant \(Z\) is added at a concentration of 2% vol., for test blocks made from PA6, Teflon and POM the friction force is higher in polymer fluid with weighting additives and lubricant Y at a concentration of 2% vol. After analyzing all the friction forces measured on the block made from different materials in tested polymer drilling fluid with and without weighting additive and with two different lubricants of X, Y and Z, at a concentration of 2% vol., using Equation (1) the friction factor was calculated for each block made from different materials. Table 3 shows the friction factor for each block made from different materials in polymer mud with and without weighting additive in which one of two lubricants of X, Y and Z is added at a concentration of 2% vol. \[\text{Coefficient of friction}=\frac{\text{Torque reading}}{100} \tag{1}\]  
From Table 2 it can be seen that the value of the friction factor for each block in the polymer mud with weighting additive in which one of three lubricants, X, Y and Z, was added at a concentration of 2% vol. is higher than for those in polymer mud without weighting additives and with the same concentration of lubricant. The increase  
Figure 13: The friction forces measured on the block made from different materials in tested polymer drilling fluid with weighting additive and with lubricant \(Z\) at a concentration of 2% vol. (PWLZ2%). in the friction factor value in polymer mud with weighting additives and lubricant at a concentration of 2% is the result of the addition of solid particles of different size to the mud system. After analyzing all the measured values of friction force for each block in all four drilling fluids, it was concluded that after 15 min of testing the lowest value of friction force was registered for the Teflon block compared to the blocks made of steel (Table 1), PA6 and POM in each polymer fluid with lubricant at a concentration of 2% with and without weighting additives. Figure 14 shows the comparison of three lubricants, X, Y and Z, added at a concentration of 2% vol. to polymer fluid without weighting additives (PL2) for the Teflon block.