With growing awareness of the environmental impact of some conventional production chemicals and concerns about the depletion of non-renewable natural resources, increased efforts are being made to use renewable and non-toxic materials in the oilfield. In this study, a potential green scale inhibitor was developed from the skin of red onions and evaluated for calcium sulphate, calcium carbonate and barium scale inhibition. Based on the different extraction processes utilized, two products were obtained and characterized using FTIR and SEM and evaluated using a static jar test procedure. The FTIR results confirmed the bands that make up the major constituents (quercetin) and other important compounds, which supports the present study. Laboratory evaluation show that ROSE can efficiently inhibit calcium sulphate scale and barium sulphate scales with a good inhibition rate of greater than 75% at an optimum dosage. Effect of temperature and dosage on inhibition performance revealed that ROSE is stable at higher temperatures and can effectively inhibit calcium and barium sulphate scales at nearly the same rate without degradation but requires additional dosage to produce same result for calcium carbonate scale. Also, the effect of time reveals that scale inhibitor performs a continuous CaSO4 and CaCO3 inhibition. Not only does ROSE perform excellently in the laboratory condition as a green scale inhibitor, but it also show a relatively close performance rate when compared to an existing commercial inhibitor which indicate that ROSE has a high potential for use in the oil industry.

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The demand for greater efficiency and large capacity for liquefaction process is inevitable for optimization. This study presents the sensitivity analysis of the factors that affects liquefaction processes of natural gas. Some of these factors are the natural gas pressure, temperature and composition on the single mixed refrigerant liquefaction process was simulated using ASPEN HYSYS 8.6 software. The effects of these parameters on specific power, power consumption and refrigerant flow rate of the process were simulations and examined. At constant pressure, temperature decreased from 15 to 5°C resulted in a 15% decrease in specific power and an increase from 15 to 25 °C resulted to 40% increase. At constant temperature, a decrease in natural gas pressure from 60 to 30bar and increase in specific power from 0.387 to 0.452 kWh/kg-LNG was observed which amounts to a 16.80% increase and when increased from 60 to 90bar specific power decreases from 0.387 to 0.348kWh/kg-LNG about 10.08 % decrease. Thus, when natural gas is supplied at a given pressure and temperature, a decrease in supply pressure will increase power consumption and an increase in supply pressure will decrease power consumption. The useful exergy for the system was about 26% of the total energy (46.42MW) available, indicating that about 74% of energy supplied by the compressor ended up as losses in different components in the process liquefaction cycle. However, the largest loss occurred in LNG heat exchanger and cooler which were to 25 and 24% respectively. The simulation results showed that, natural gas supplied at 150MMScf, 60bar and 15°C gave rise to LNG production of about 0.95MTPA.

Scale deposits are a significant flow assurance issue in oil and gas operation with huge financial consequences. Not only does scaling drastically impair well performance, but it also has the potential to permanently destroy formation and equipment. Scale inhibitors are commonly used to prevent the accumulation of scales. A good scale inhibitor should be stable at the minimum effective inhibitor concentration under imposed operating conditions without interfering with or being affected by other chemical additives. However, most conventional scale inhibitors that possess these attributes, do not meet environmental restrictions which make them unfavorable for continuous application, prompting the industry to focus more on developing eco-friendly substitutes. This paper reviews the various types of scale inhibitors and general scale inhibition mechanism, summarizes scale concepts and ultimately, assesses the potential of flavonoids from natural plants as potential green scale inhibitors.