## 3 Results
### Sag Test
This may be an indication of the role of the temperature increase in the dynamic sagging tendencies. However, 1.72 ppg was above the safe boundary. Theoretically, the effect of temperature on fluid samples, which increases viscosity, may result in increased sagging tendencies. When the temperature increases, molecules move apart, hindered settling is reduced, and free settling is initiated, which may result in a reduction in the suspending ability of the fluid. However, this was more prominent in Fluid 0 than in Fluid 3 due to the absence of fly ash in Fluid 0. Figure 12: Effect of ratios of fly ash on static sagging of weighting agents. Figure 14 presents the effect of different ratios of fly ash on the dynamic sagging propensity of barite and ilmenite at 400 \({}^{\circ}\)F. At 0 lb/bbl of fly ash, a percentage sag reduction of 3.9% was observed for barite. The addition of 4 lb/bbl of fly ash reduced the dynamic sagging of barite and ilmenite by 63.9% and 63.1%, respectively. It can be deduced that the influence of 4 lb/bbl fly ash was slightly more effective in the barite-densified fluid, with a difference of 0.8%, than in the ilmenite-densified fluid. Even though the dynamic sag test simulates sagging tendencies while the drill string is rotating, the influence of the weight material density on the annular velocity may be significant as solids tend to settle out. The chances of ilmenite particles settling faster may be an indication of their high density, which may result in a higher VSST than barite particles of the same size. Due to this, it may be logical to mitigate dynamic sagging at a reasonably high annular velocity that is at least sufficient to overcome the opposing force of the solid particles and keep them in motion while the fluid is being circulated in the wellbore. This is necessary to prevent well control challenges, which are usually the outcome of sagging. Figure 14: Effect of ratios of fly ash on the dynamic sagging of weighting agents. Figure 13: Dynamic sag results for Fluid 0 and Fluid 3 at different temperatures. Based on almost the same mud formulation as [PERSON] et al. [6]. Figure 15 compares the efficiency of fly ash as an anti-sagging additive with that of vermiculite [6]. A 4 lb/bbl of fly ash was found to be more effective in mitigating barite sag than ilmenite sag, as an SF of 0.5021 and 0.504 were obtained, respectively, at 0\({}^{\circ}\) wellbore inclinations. A percentage decrease of 1.176% SF was observed for ilmenite using fly ash as an anti-sagging additive over vermiculite with barite as a weighting agent. In like manner, a percentage decrease of 1.5490% was recorded for fly ash (barite) over vermiculite (barite). A similar trend was also observed at 45\({}^{\circ}\) wellbore inclination. However, a marginal difference of 0.003 SF was exhibited by the fly ash-based mud samples (barite and ilmenite). From the results presented in Figure 15 and Table 2, fly ash may be a more efficient anti-sagging additive than vermiculite. This may be due to the chemical reaction between these additives and the base fluids. Economically, fly ash may be cheaper than vermiculite because it is an industrial waste, while vermiculite occurs naturally as a clay mineral that can be mined or purchased at a cost.