# Green Approach in Water-Based Drilling Mud Design to Increase Wellbore Stability
## 3 Results
For mud samples containing particles from 0.10 to 0.16 mm, a similar trend was observed as that for mud samples containing particles less than 0.10 mm, with a slightly greater decrease in the value of PPT filtration (35 and 20 mL (B muds) compared to 37 and 22 mL (mud samples A)). Spurt loss was significantly lower for mud samples containing MPP less than 0.10 mm in size at a concentration of 2% by volume of water (A4) (10 mL) compared to values measured with BM (16 mL). For muds containing particles from 0.10 to 0.16 mm, a similar trend was observed as for muds containing particles smaller than 0.10 mm, with a slightly larger decrease in the value of spurt loss (7 and 4 mL (mud samples B)) compared to 13 and 10 mL (A muds)). Figure 7 shows the swelling of the pellets in the base mud (BM) and in mud samples with added MPP (particles less than 0.1 mm) within 2 and 24 h (mud samples A1-A4) at room temperature. After 2 h, the swelling of the pellets in the different formulations of mud A was reduced regardless of the concentration of MPP, and ranged from 11.2% to 15.2% compared to the swelling of the pellets in the base mud (18.9%). After 24 h, pellet swelling was also reduced regardless of MPP concentration, and ranged from 43% to 52.9% compared to pellet swelling in the base mud (72.3%). With the addition of MPP, pellet swelling was 52.9% at the lowest tested concentration of 0.5% by volume of water (A1), while increasing the concentration up to 2% did not express the same intensity of pellet-swelling decrease. Moreover, a slight increase of 2.2% in pellet swelling (from 43% (A3) to 45.2% (A4)) was observed after the addition of MPP at a higher concentration than 1.5% by volume of water. Figure 8 shows the swelling of the pellets in the base mud (BM) and in muds with added MPP (particles from 0.10 to 0.16 mm) within 2 and 24 h (mud samples B1-B4) at room temperature. Figure 7: Pellet swelling in base mud and in mud with added MPP (particles less than 0.1 mm) within 2 and 24 h at room temperature. After 2 h, the swelling of the pellets in the different formulations of mud B was reduced regardless of the concentration of MPP and ranged from 10.1% to 16.5% compared to the swelling of the pellets in the base mud (18.9%). After 24 h, pellet swelling was also reduced regardless of the concentration of MPP, and ranged from 39.8% to 59.7% compared to pellet swelling in the base mud (72.3%). When MPP was added at a concentration of 0.5% by volume of water (B1), the measured swelling was 59.7%. A concentration of MPP of 1% by volume of water and above is required to significantly reduce pellet swelling, ranging from 50.1% for mud B2 to the best result (39.8%) obtained for a mud containing 2% of MPP by volume of water (B4). Figure 9 shows the swelling of the pellets in the base mud (BM) and in mud with added MPP (particles less than 0.10 mm) within 2 and 24 h ( mud samples A1-A4) at 90 \({}^{\circ}\)C.  
After 2 h, the swelling of the pellets was lower regardless of the concentration of MPP, ranging from 18.5% to 24.2% compared to the swelling of the pellets in the base mud (27.3%). After 24 h, the swelling of the pellets was also decreased regardless of the  
Figure 8: Pellet swelling in base mud and in mud with added MPP (particles from 0.1 to 0.16 mm) within 2 and 24 h at room temperature. Figure 9: Pellet swelling in base mud and in mud with added MPP (particles less than 0.1 mm) within 2 and 24 h at 90 \({}^{\circ}\)C.  
concentration of the MPP, and ranged from 64.8% (A4) to 99.1% (A1) compared to the swelling in the base mud (115.5%). Increasing the concentration of MPP from 0.5% (A1) to 1% by volume of water (A2), pellet swelling continued to decrease (from 99.1% (A1) to 69.4% (A2)), but this trend did not continue with the same intensity with a further increase in MPP concentration, so the pellet swelling was 69.4% (A3) and 64.8% (A4).