## 3 Results
### Sag Test
Comparatively, Figures 10 and 11 graphically describe the positive impacts of fly ash concentrations on the weighting agents (barite and ilmenite). Generally, Fluid 4, which is  
Figure 8: Static sag results for base fluid (0 lb/bbl of fly ash plus 350 lb of barite). Figure 9: Static sag results for Fluid 3 (3 lb/bbl of fly ash plus 350 lb of barite). a barite-densified fluid, yielded less SF than Fluid 5, which is an ilmenite-densified fluid. For instance, at 0\({}^{\circ}\) and 400 \({}^{\circ}\)F, Fluid 4 yielded less SF of 0.5107 than Fluid 5 with SF of 0.5130. With 0 lb/bbl of fly ash, the barite-densified fluid exhibited a lower percentage SF of 1.4% (0.545-0.537) than the ilmenite-densified fluid. This difference may be traceable to the impact of the specific gravity of the weighting agents. Ilmenite has a higher specific gravity of about 4.7 g/cm\({}^{3}\) than barite, which is approximately 4.20 g/cm\({}^{3}\). Despite having the same particle size (D50), ilmenite and barite are 22 \(\upmu\)m and 6.5 \(\upmu\)m, respectively. Therefore, ilmenite may sag faster than barite in the fluid column, resulting in a higher SF. It can be inferred that the addition of 4 lb/bbl of fly ash further lowered the static sag SF of the weighting agents at various inclinations and temperatures investigated. However, fly ash was discovered to be more effective as an anti-sagging additive in barite-densified fluid than in ilmenite-densified fluid. This is more evident in Figure 12, as barite-densified fluid yielded a lower SF than ilmenite-densified fluid for the same quantity of fly ash utilized. A percentage sag reduction of 3.4% and 2.4% was exhibited by 4 lb/bbl fly ash in barite-densified fluid (Fluid 4) and ilmenite-densified fluid (Fluid 5), respectively. Figure 11: Static sag result for Fluid 5 (4 lb/bbl of fly ash plus 350 lb of ilmenite). Figure 10: Static sag results for Fluid 4 (4 lb/bbl of fly ash plus 350 lb of barite). However, there are clear differences between the anti-sagging properties of the ilmenite-densified fluid and barite-densified fluid. This may be caused by factors like specific gravity, particle size distribution, and chemical composition. Ilmenite has a higher specific gravity than barite, which may result in higher sagging tendencies against barite with a lower specific gravity. The D\({}_{50}\) particle size of ilmenite was 22 \(\upmu\)m, while barite was 6.5 \(\upmu\)m, reducing the anti-sagging efficiency of the ilmenite-densified fluid. The chemical composition of ilmenite and barite, as analyzed by XRF, may also be a contributory factor. Theoretically, the sagging mitigating ability exhibited by fly ash may be traceable to its properties. The fly ash surface area varies from 170 to 1000 m\({}^{2}\)/kg and has a specific gravity of about 2.1-3.0. Due to its surface area, solubility, and specific gravity, a quantity of fly ash may have a reasonable impact on its surroundings and form a kind of suspending agent in water, which could retard the settling of barite. This tendency may be supported by the activity of a natural suspending agent like xanthan gum and copolymer included in the fluid's formulation. Thereby exhibiting an acceptable performance as an anti-sagging additive. In field applications, despite obtaining acceptable values of SF at notorious angles, usually close to 60\({}^{\circ}\), it is suggested that drillers should avoid drilling at these slopes. As shown in Figure 13, it can be inferred that the dynamic sagging results of Fluid 3 (based fluid plus 3 lb/bbl of fly ash) exhibited an anti-sagging effect on the fluid column. However, the reverse was the case for Fluid 0 without fly ash, as it provided a sagging performance and was above the safe boundary. When both fluids were compared, Fluid 3 had a percentage decrease of 69, 70, 70, and 63% in VSST observed at 250 \({}^{\circ}\)F, 300 \({}^{\circ}\)F, 350 \({}^{\circ}\)F, and 400 \({}^{\circ}\)F, respectively. The highest values of VSST, 1.72 and 0.63 ppg, were experienced at 400 \({}^{\circ}\)F by both fluids 0 and 3, respectively.