Wax deposition in production tubing and pipelines is very critical in Nigeria petroleum industry. It can lead to a reduction in production, shut-in of wells, choking of flow lines, failure of downhole equipment, increased power requirement and loss in revenue. In the bid to address this issue, a Niger Delta crude oil sample was characterized in this study to know its wax deposition tendency and other chemical properties. The effect of temperature on the viscosity of the crude oil sample was studied, and the degree of viscosity reduction (DVR) of the crude oil sample in the presence of poly (ethylene-butene) (PEB) and nano-aluminium oxide (Al2O3) blend at different temperatures was evaluated. 100 ppm of nano-Al2O3 blend with 1000 ppm, 2000 ppm and 5000 ppm of PEB, respectively, was added to the crude oil sample at different temperatures, and the degree of viscosity reduction (DVR) in each blend at 10 °C, 15 °C, 20 °C, 30 °C and 35 °C was evaluated. The blend with 2000 ppm of PEB with 100 ppm nano-Al2O3 is the best for offshore application as it gave the highest DVR of 77.9% and 73.7% at 10 °C and 15 °C, respectively, while the other blends gave a DVR of about 70% at 10 °C and 15 °C. As the crude sample temperature approached the wax appearance temperature of 29 °C, the DVR of PEB/Al2O3 blend drastically reduced. PEB/Al2O3 blend inhibited wax precipitation, and at low temperatures, a significant reduction in the viscosity of the crude oil sample was observed, which makes it a good recommendation for offshore application.

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This research examines the use of 75nm Zinc Oxide nanoparticles (Nano ZnO) and Polyethylene Butene (PEB) in reducing the viscosity of Nigerian waxy crude oil. The rheology of the crude oil was studied by measuring the viscosity and shear stress of crude samples contaminated with varying concentration of PEB (500ppm, 1000ppm, 2000ppm, 3000ppm, 4000ppm and 5000ppm), varying concentrations of Nano ZnO (1wt%, 2wt%, 3wt% and 4wt%) and different blends of PEB and Nano ZnO at temperatures of between 10°C to 35°C and shear rates from 1.7 to 1020s-1. From Rheological Modelling analysis conducted, the Power law pseudoplastic model was the best fit for the experimental data with a regression coefficient of 0.99. Analysis of crude sample before addition of inhibitor showed evidence of non-Newtonian fluid behaviour as the shear stress-shear rate relationship curves were nonlinear due to wax precipitation at low temperatures (10°C to 15°C). The waxy crude demonstrated shear thinning behaviour with increasing shear rates (increasing turbulence) and the viscosity reduced with increasing temperature. The addition of inhibitors (PEB, Nano ZnO and their blends) effected Newtonian fluid behaviour in the crude samples as the shear stress-shear rate relationship curves were linear at all temperatures under study. The optimum concentration of the inhibitors in this study is 2000ppm PEB (causing 33% viscosity reduction) and 1wt% Nano ZnO (effecting 26% viscosity reduction). The best concentration of the blend was 2000ppm PEB blended with 1wt% Nano ZnO which effected a viscosity reduction of 41%. The research demonstrates the novel application of the blend of Nano ZnO and PEB in improving flowability of Nigerian waxy crude oil especially in offshore conditions with prevailing cold temperatures.

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Sub-sea developments produce greater flow assurance and intervention challenges. Low seawater temperature may lead to hydrate formation in subsea pipelines. The effect of N-Vinylcaprolactam in preventing hydrate plug formation in gas dominated systems was studied using a 12 meter long closed loop designed for hydrate studies. The experiments were conducted by circulating gas and water at 150psi in the presence of 0.04wt% or 0.05wt% concentration of N-Vinylcaprolactam. The equivalent weight of N-Vinylcaprolactam used wasobtained based on the weight of water fed into the loop. Results showed that the loop pressure declined to 105 psi when 0.05wt% N-Vinylcaprolactam was used as inhibitor. However, when 0.04wt% of N-Vinylcaprolactam was used in the constant volume experiment, the loop pressure decline to 83psi implying that more gas was used up in forming hydrates. In the uninhibited system, the pressure declined from 150psi to 70psi and hydrate plug was noticed. This implies that at 150psi, 0.05wt% concentration of N-Vinylcaprolactam was effective at preventing hydrate formation in the experimental hydrate loop. Mathematical models describing the performance of N-VCap in the experimental loop were derived from experiments conducted. Hydrates may form in subsea pipelines in the presence of inhibitors if the appropriate dosage is not used. It is therefore important for the engineer to evaluate the effective inhibitor dosage prior to field implementation.