Humphrey Nwenenda Dike

Water-based drilling fluid systems are gaining popularity for their environmental friendliness and low cost. These fluids are highly sensitive to products used to modify fluid properties and control fluid loss. Traditional additives like carboxymethyl cellulose (CMC) work well but come with environmental issues and high costs and alternatives from agricultural sources are being sought. The potential of using acetylated yam peel starch (AYPS) and acetylated plantain peel starch (APPS) as substitutes for CMC in water-based drilling mud formulation under ambient and simulated downhole conditions of 27 °C and 150 °C, respectively, was investigated. The peels of yams and plantain, starchy foods, were chemically modified through acetylation and added to the drilling mud formulation at proportions of 0.2–1.0 g. FTIR confirmed the success of the modification by the presence of characteristic bands of carbonyl (C=O) absorption at 1730–1750 cm⁻¹ and by the increase in C–O bands after the modification, which means that acetyl groups were successfully incorporated. The highest mud density recorded was 9.16 kg/m³ (ppg) with 1.0 g of additives, and the pH values ranged from 8.10 to 9.50, which is good for drilling operations. The plastic viscosity was found to be 4–7 cP at 27 °C and 3–6 cP at 150 °C for AYPS and APPS, respectively, which were lower than the CMC value but still retained viscosity at high temperature. The yield point values for the samples were 2–5 lb/100 ft² at 27 °C and 1–6 lb/100 ft² at 150 °C, which were slightly better for AYPS. Thermal aging did not significantly affect gel strength, which increased upon exposure to high-temperature conditions, especially at high additive concentrations, indicating that the rheological properties were preserved. Filtrate losses were 12–16.8 mL for AYPS and 12.5–17.2 mL for APPS under low-pressure, low-temperature conditions, which are similar to CMC (11–16 mL). APPS was the most effective filtrate-loss control of the modified starch systems under the HPHT conditions. Rheological modeling showed that shear-thinning behavior is predominant, and the Herschel–Bulkley and Casson models provided the best fits. In general, the acetylated yam and plantain peel starches have shown promising properties as alternatives for CMC for enhancing rheological properties and controlling fluid loss in water-based drilling fluids.

Some additives currently used to enhance drilling mud’s rheological qualities have a substantial economic impact on society. Carboxymethyl cellulose (CMC) and calcium carbonate (CaCO₃) are currently imported. Food crops have influences on food security; hence, this research explored the potential of utilizing cow bone powder (CBP), a bio-waste product and a renewable resource, as an environmentally friendly fluid-loss additive for drilling applications, in comparison with CaCO₃. Both samples (CBP and CaCO₃) were evaluated to determine the most efficient powder sizes (coarse, medium, and fine powder), concentrations (5–15 g), and aging conditions (before or after aging) that would offer improved rheological and fluid-loss control. The results obtained showed that CBP had a significant impact on mud rheology when compared to CaCO₃. Decreasing the particle size (coarse to fine particles) and increasing the concentration from 5 to 15 g positively impacted mud rheology. Among all the conditions analyzed, fine-particle CBP with a 15 g concentration produced the best characteristics, including in the apparent viscosity (37 cP), plastic viscosity (29 cP), and yield point (25.5 lb/100 ft²), and a gel strength of 16 lb/100 ft² (10 s) and 28 lb/100 ft² (10 min). The filtration control ability of CaCO₃ was observed to be better than that of the coarse and medium CBP particle sizes; however, fine-particle-size CBP demonstrated a 6.1% and 34.6% fluid-loss reduction at 10 g and 15 g concentrations when compared to respective amounts of CaCO₃. The thermal behavior of the Mud Samples demonstrated that it positively impacted rheology before aging. In contrast, after aging, it exhibited a negative effect where samples grew more viscous and exceeded the API standard range for mud properties. Therefore, CBP’s excellent rheological and fluid-loss control ability makes it a potential, sustainable, and economically viable alternative to conventional materials. This superior performance enhances the thinning properties of drilling muds in stationary and circulating conditions.

High technical and financial risks are involved in exploring and exploiting new fields; hence, greater focus has placed on the development of environmentally friendly, cost-effective, and enhanced oil recovery (EOR) options for existing fields. For reservoirs producing high-density crudes and those with high interfacial tensions, water flooding is usually less effective due to density differences—hence the advent of polymer and surfactant flooding. For cost-effective and eco-friendly EOR solutions, a biopolymer and a surfactant synthesized from Jatropha seeds are used in this study to determine their effectiveness in increasing the oil recovery during core flooding analysis. The experiment involved an initial water flooding that served as the base cases of three weight percentages of polymers and polymeric surfactant solutions. The results for the polymer flooding of 1 wt%, 1.5 wt%, and 2 wt% showed an incremental oil recovery in comparison to water flooding of 16.8%, 17%, and 26%, while the polymeric surfactant mixtures of 5 wt% of surfactant and 1 wt%, 1.5 wt%, and 2 wt% of a polymer recorded 16.5%, 22.3%, and 28.8%, and 10 wt% of surfactant and 1 wt%, 1.5 wt%, and 2 wt% of a polymer recorded incremental oil recoveries of 20%, 32.9%, and 38.8%, respectively.