Yahaya Danjuma Baba

The sub-Saharan region in Africa is one of the ideal geographic locations for generating solar electricity. Despite the inexhaustible renewable energy resources residing in the region, many households remain disadvantaged without electricity. This section reviews the development of solar energy systems in Africa, in particular, sub-Saharan regions and the viable economic prospects for its energy sectors. Highlights are provided on the currently deployed solar infrastructure and coverage, as well as critical constraints restricting the extensive acquisition and installation of solar technologies. Furthermore, the chapter recommends initiatives for socio-economic developments and strategic policies to entice international support for sustainable solar projects and mitigation against causes of climate change. While the chapter concludes by emphasising on integration of power systems and sustainable mechanisms, the review suggests further investigation into solar energy economics, policies, and innovative ways to improve the adoption of solar energy in sub-Saharan Africa. Insights provided in this chapter are expected to help researchers, policymakers, and stakeholders establish sustainable strategies with the least climate impacts.

Proper selection and application of interfacial friction factor correlations has a significant impact on prediction of key flow characteristics in gas–liquid two-phase flows. In this study, experimental investigation of gas–liquid flow in a vertical pipeline with internal diameter of 0.060 m is presented. Air and oil (with viscosities ranging from 100–200 mPa s) were used as gas and liquid phases, respectively. Superficial velocities of air ranging from 22.37 to 59.06 m/s and oil ranging from 0.05 to 0.16 m/s were used as a test matrix during the experimental campaign. The influence of estimates obtained from nine interfacial friction factor models on the accuracy of predicting pressure gradient, film thickness and gas void fraction was investigated by utilising a two-fluid model. Results obtained indicate that at liquid viscosity of 100 mPa s, the interfacial friction factor correlation proposed by Belt et al. (2009) performed best for pressure gradient prediction while the Moeck (1970) correlation provided the best prediction of pressure gradient at the liquid viscosity of 200 mPa s. In general, these results indicate that the two-fluid model can accurately predict the flow characteristics for liquid viscosities used in this study when appropriate interfacial friction factor correlations are implemented.

Hydrocarbon exploration basically requires effective drilling and efficient overpowering of frictional and viscosity forces. Normally, frictional power losses occur in deep well systems and it is essential to analyse each component of any well system to determine where exactly pressure is lost, and this can be done using Nodal Analysis. In this study, nodal analysis has been carried out with the use of PROSPER, a software for well performance, design and optimisation. Artificial lifts can then be used to solve the problem of frictional power losses. To increase the production of Barbra 1 well in the Niger Delta and hence extend its functional life, we have applied nodal analysis. Modelling results for three artificial lift methods; continuous gas lift, intermittent gas lift and electrical submersible pump were found to be 1734.93 bbl/day, 451.50 bbl/day and 2869 bbl/day respectively. The output from the well performance without artificial lift was 1370.99 bbl/day by applying Darcy’s model. Meanwhile, the output from the well without artificial lift is 89.90 bbl/day when aided with productivity index (PI) entry, the normal model for intermittent gas lift. Hence, from the comparative analysis of the results obtained from this study, it was deduced that when artificial lifts are employed, the well output increases significantly from 1370.99bbl/day to 2869 bbl/day (electrical submersible pump). This study concludes that wells such as Barbra 1 are good candidates for artificial lift, and this is evidenced by increasing productivity. Keywords: Production optimisation, nodal analysis, prosper simulator and barbra well.

In this study, a deepwater pipeline-riser system that experienced hydrates was modelled in MAXIMUS 6.20 (an integrated production modelling tool) to understand, predict and mitigate hydrates formation in typical deepwater system. Highlights of the results from this study suggest that the injection of low-dosage hydrate inhibitors (LDHIs) into the hydrate-forming structures within the multiphase flow stream disperses the hydrates particles in an irregular manner and subsequently decreases the nucleation rate of the hydrate and prevents the formation of hydrates. This study found that the cost of using monoethylene glycol was significantly higher than that of LDHI by over $500/day although low-dosage hydrate inhibitors have initial relatively high CAPEX. In the long run, its OPEX is relatively low, making it cost-effective for hydrate inhibition in deepwater scenarios.

Slug translational velocity, described as the velocity of slug units, is the summation of the maximum mixture velocity in the slug body and the drift velocity. Existing prediction models in literature were developed based on observation from low viscosity liquids, neglecting the effects of fluid properties (i.e., viscosity). However, slug translational velocity is expected to be affected by the fluid viscosity. Here, we investigate the influence of high liquid viscosity on slug translational velocity in a horizontal pipeline of 76.2-mm internal diameter. Air and mineral oil with viscosities within the range of 1.0–5.5 Pa·s were used in this investigation. Measurement was by means of a pair of gamma densitometer with fast sampling frequencies (up to 250 Hz). The results obtained show that slug translational velocity increases with increase in liquid viscosity. Existing slug translational velocity prediction models in literature were assessed based on the present high viscosity data for which statistical analysis revealed discrepancies. In view of this, a new empirical correlation for the calculation of slug translational velocity in highly viscous two-phase flow is proposed. A comparison study and validation of the new correlation showed an improved prediction performance.