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Facilitating optimal operations of a wave energy converter using a preeminent mooring line: an entropy weight-VIKOR method

Nwaoha Thaddeus C., Udosoh Nsisong E.

Journal of Mechanical and Energy Engineering

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2022

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Vol. 6, No 1

77--83

EN

This study employed viable methods for the selection of a preeminent mooring line amongst other alternatives for the mooring of a floating wave energy converter (WEC) in shallow waters. Conventional mooring lines for WEC mooring are identified for an optimal selection exercise. A combination of the Entropy Weight and Visekriterijumska Optimizacijia I Kompromisno Resenje (VIKOR) methods is utilized in the aforementioned exercise. The two methods are effectively used in an assessment of the attributes and performance of various mooring lines in practical application. The result obtained demonstrated that a steel wire rope is the best mooring line suitable for WEC system operations. It constitutes a good reference to marine and offshore engineering industries in decision making related to optimal mooring lines suitable for the mooring of a WEC system in shallow waters.

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Demonstration of MEOR as an alternative enhanced oil recovery technique in Nigeria offshore oilfield

Udosoh Nsisong E., Nwaoha Thaddeus C.

Journal of Mechanical and Energy Engineering

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2020

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Vol. 4, No 3

277--283

EN

Eni oilfield has been experiencing production decline with increase in water output. The implementation of enhanced oil recovery (EOR) can help to extract some percentages of the original oil in place (OOIP). EOR methods are capital intensive and few are environmental hazardous. In a bid to address this issues, this paper discusses on an alternate economically viable enhanced oil recovery technique which has the potential to curb the challenges of other conventional EOR methods. This work suggested a 3 stage approach of applying microbial enhanced oil recovery (MEOR) method for oil recovery in Eni field. The reservoir characteristics in Eni field were studied, the average porosity value of the reservoirs is between 0.238 and 0.241, while water saturation ranges between 0.127 and 0.13. Other production data include; Initial reservoir pressure which ranges from 2328 to 2553 Psia and has a reservoir temperature ranging from 170°F to 180°F. The Average API gravity ranges from 20.5 to 34.2, while the initial GOR ranges from 350 to 396. Oil viscosity was between 0.57cp to 2.57cp while gas viscosity was between 0.65cp to 0.67cp. The reservoir characteristics and parameters were found suitable for the application of MEOR technique for effective oil drainage from the delineated reservoir compartments. Microbial flooding was found to be matured in reservoirs with temperature less than 200°F, brine salinity not more than 100,000 ppm, water depth not more than 3500m and permeability should be above 30 (Md). It is recommended that MEOR approach should be applied in Eni Oilfield for increment of oil production and reduction in water cut due to its efficiency and economic viability.

3

Use of hybrid approach in facilitation of design of ship hydrostatic parameters under uncertainty

Nwaoha Thaddeus C., Idubor Fabian I.

Journal of Mechanical and Energy Engineering

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2019

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Vol. 3, No 1

31--42

EN

Hydrostatic parameters of a ship are very important in ship design. The importance of the parameters compared to one another need to be revealed in realm of uncertainty, so as to avoid design error. In view of this, a fuzzy-analytical hierarchical process (Fuzzy-AHP) method is utilized in addressing the subject under investigation. The fuzzy logic is used to address uncertainty in pairwise comparison exercise, so as to facilitate the estimation of order of importance of hydrostatic parameters. In this research, the engineering judgements of three designers in analysis of importance of hydrostatic parameters are aggregated and processed using the Fuzzy-AHP methodology. The result produced in the study showed that hydrostatic parameters are importance in order of moments of inertia of vessels (MIV), mass displacement (MD), tons per centimeter immersion (TPCI), coefficients of form (CF), centers of buoyancy (CB), metacentric heights of vessels (MHV), ship waterplane area (SWA), longitudinal center of floatation (LCF), volume displacement (VD) and wetted surface area (WSA) with weight values of 0.218, 0.095, 0.078, 0.083, 0.074, 0.1, 0.46, 0.108, 0.209 and 0.028 respectively.