# Green Approach in Water-Based Drilling Mud Design to Increase Wellbore Stability
## 4 Discussion  
To determine the effect of MPP on filtration properties and pellet swelling, all results were compared. From the data shown in the Table 5, reduction in API filtration was evident for all tested mud samples relative to API filtration measured with the base mud (BM), expressed as a percentage. Comparing measured API filtration results with both particle sizes at the same concentrations of MPP, at higher concentrations (1% by volume of water and above) better results were obtained, with powder having larger particles (from 0.10 to 0.16 mm), while at low concentrations (0.5% by volume of water), better results were achieved with MPP having smaller particles than 0.10 mm. Regardless of the permeability of the disc used in the tests (0.4 or 0.75 \(\upmu\)m\({}^{2}\)), a positive effect of the addition of mandarin powder on the PPT filtration of the mud was observed, since its value decreased significantly in all cases compared to the values obtained with the base mud (BM). A comparison of PPT filtration results measured with both particle sizes at the same concentrations of MPP through a 0.4 \(\upmu\)m\({}^{2}\) (400 mD) ceramic disc shows that, at a concentration of 1% by volume of water, slightly better results were obtained with MPP with particles less than 0.10 mm (42.31% compared to 38.46%), while at a concentration of 2% by volume of water, slightly better results were obtained with MPP with particles from 0.10 to  
Figure 10: Pellet swelling in base mud and in mud with added MPP (particles from 0.10 to 0.16 mm) within 2 and 24 h at 90 \({}^{\circ}\)C.  
0.16 mm (53.85% compared to 50%). At a concentration of 1% by volume of water, results of spurt loss for mud samples containing MPP particles less than 0.10 mm were significantly better (75% reduction) than the results for mud samples containing MPP particles from 0.10 to 0.16 mm (25%). At a concentration of 2% by volume of water, regardless of MPP size, the reduction in spurt loss was similar (50%). Comparing the PPT filtration results measured with both particle sizes at the same concentrations of MPP through a 0.75 um\({}^{2}\) (750 mD) ceramic disc, it is shown that slightly better results were obtained with MPP particles from 0.10 to 0.16 mm (32.69% compared to 28.85% at a concentration of 1% by volume of water and 61.54% compared to 57.69% at a concentration of 2% by volume of water). The same trend was observed in determining the value of spurt loss, with significantly better results obtained with powders with particles from 0.10 to 0.16 mm (56.25% related to 18.75% at a concentration of 1% by volume of water and 75% related to 37.75% at a concentration of 2% by volume of water). Figure 11 shows the pellet swelling reduction in mud samples with added MPP within 24 h related to the pellet swelling measured with the base mud at room temperature and 90 \({}^{\circ}\)C, expressed as a percentage. Figure 11: Pellet swelling reduction in different mud samples with added MPP in regard to base mud (BM) within 24 h. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & & & & & \\ \hline
**A1** & **A2** & **A3** & **A4** & **B1** & **B2** & **B3** & **B4** \\ \hline \multicolumn{8}{c}{**Reduction in API filtration (\%)**} \\ \hline
25 & 25 & 36 & 36 & 11 & 28 & 42 & 44 \\ \hline \multicolumn{8}{c}{**Reduction in PPT filtration (\%) through 0.4 μm\({}^{2}\) (400 mD) disk**} \\ \hline - & 42.31 & - & 50 & - & 38.46 & - & 53.85 \\ \hline \multicolumn{8}{c}{**Reduction in PPT filtration (\%) through 0.75 μm\({}^{2}\) (750 mD) disk**} \\ \hline - & 28.85 & - & 57.69 & - & 32.69 & - & 61.54 \\ \hline \multicolumn{8}{c}{**Reduction in spurt loss volume (\%) through 0.40 μm\({}^{2}\) (400 mD) disk**} \\ \hline - & 75 & - & 50 & - & 25 & - & 50 \\ \hline \multicolumn{8}{c}{**Reduction in spurt loss volume (\%) through 0.75 μm\({}^{2}\) (750 mD) disk**} \\ \hline - & 18.75 & - & 37.5 & - & 56.25 & - & 75 \\ \hline \hline \end{tabular}
\end{table}