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A MODEL INCORPORATING WIND AND TEMPERATURE EFFECTS ON THE SPREAD OF CRUDE OIL SPILL ON NIGER DELTA COASTAL LINE
ABSTRACT
The Niger Delta coastal line is one of Nigeria’s richest and largest navigation corridors, characterized by very windy and temperature conditions, such that with possibility of any oil spill incident, catastrophic environmental degradation will occur. Available mathematical models for predicting crude oil spills spread rate will not provide accurate prediction of spread rate under ambient temperature changes and wind effects. This work is concerned with developing a model that incorporates wind and temperature effects on the spread rate of crude oil spill on Niger Delta coastal line. The model of Susu and Abowei (1998) were reviewed and their limitations noted. Further improvement is made by considering spreading in the regime where the inertial and viscous forces counterbalance gravity and takes into account climatic factors such as the effects of winds and temperature. The effective wind velocity and direction on the oil slick were resolved by the application of trigonometric principles, analysis and correlations. Temperature effects in both dry and wet seasons were taken into considerations using analysis and correlations. Computer simulations using Qbasic software were done with existing crude oil field data and graphical analyses were made from the output. Laboratory experiments were performed to generate primary data needed for model validation. The model was validated and found to give 60% prediction of spread than the existing models. The analysis of the empirical and the analytical results show a 5% variation with a correlation coefficient in the range of 0.9938-0.9999 and error limit of 0.05 depending on the three crude sample used. Because the model incorporated wind effects and temperature variation which others never considered it will be useful to Petroleum Industries and Eco-Engineers interested in combating oil spill and its early containment.
KEY WORDS : Model, temperature effects, crude oil spill, Niger delta, coastal line, wind currents
TABLE OF CONTENTS
Certification i
Dedication ii
Acknowledgements iii
Table of Contents v
List of Tables vii
List of Figures and Charts viii
Nomenclature ix
Abstract xii
CHAPTER 1 INTRODUCTION
1.1 Background Information 1
1.2 Problem Statement 4
1.3 Objective of Study. 5
1.4 Justification of Study. 6
1.5 Scope of Study 7
CHAPTER 2 LITERATURE REVIEW
2.1 Crude Oil Spill 8
2.1.1 Advection 11 2.1.2 Spreading 11
2.1.3 Evaporation 12 2.1.4 Dissolution 12
2.1.5 Emulsification 12
2.1.6 Photo-oxidation 13
2.1.7 Sinking and Sedimentation 13
2.2 Historical Review 17
2.3 Review of Oil Spill models 31
2.4 Improving on the limitations from Literature Review. 49
CHAPTER 3 MATERIALS AND METHOD
3.1 List of Material. 51
3.2 Method 52
3.2.1 Improvement of Susu and Abowei’s model 52
3.2.2 Development of Equations for Spreading Coefficient
and Spreading rate. 53
3.2.2.1Development of Spreading Coefficient 53
3.2.2.2Development of Equation for Spreading Rate. 56
3.2.3 Dependence of spreading coefficient, forces of adhesion and
Cohesion on surface tension & viscosity of fluid. 60 3.2.3.1Surface tension of the fluids 60 3.2.3.2Density-Viscosity effects of the fluids. 61
3.2.4 Correlation of Numerical Model. 62
3.2.4.1Constant m and Vp 62
v
3.2.4.2Constant Cn and ratio of viscosities 64
3.2.5 Improvement of Susu and Abowei’s model 65
3.2.5.1Development of wind-induced Velocity of spread. 65 3.2.5.2 Consideration of temperature effect. 72
3.2.6 Characterisation of Spreading Regime. 76 3.2.7 Kinematic Momentum Rate. 78
3.2.8 Iterative technique and Flow Chart. 82
3.3 Experimental Technique for model validation. 84
CHAPTER 4 RESULTS AND DISCUSSION 88
4.1 Results. 88
4.1.1 Wind induced velocity of spread. 88 4.1.2 Effects of temperature variations. 88
4.1.3 Results obtained from Computer output 89
4.1.4 Experimental results Model validation. 91
4.1.5 Hypothetical Analysis 95
4.2 Discussions. 104 4.2.1 The Developed model 104
4.2.2 Comparison of developed Model with existing Model. 108
4.2.3 Model validation 109
CHAPTER 5 CONCLUSION AND RECOMMENDATION
5.1 Conclusion 111
5.2 Recommendations 113
5.3 Contributions to knowledge 114
REFERENCES 115
APPENDICES
CHAPTER ONE
INTRODUCTION
1.1 Background Information
Recently there has been growing issues over the growing contamination of Nigeria waterways particularly Niger Delta shoreline areas caused by oil spills. The Niger Delta basin of Nigeria is on the continental margin of the Gulf of Guinea in the equatorial West Africa within latitudes 3oand 6oNorth and longitudes 5oand 8oEast. The Niger Delta on Atlantic coast is about the most significant in the universe. Other world‘s known Deltas are the Nile, Mississippi, Orinoco, Ganges and Mekong (Ibru, 2015; Ifelebuegu, et al., 2017). Deltas are basically fertile, with different resources and are therefore known for huge human settlements and civilizations. The Niger Delta complex is almost most recognized basins in West Africa and really the greatest delta in Africa, (Peishi & Williams, 2010).The Niger Delta Coastal Line shown in Figure 1.1, is Nigeria’s largest navigation corridor, it is exposed to risk of being contaminated with crude oils (Agho, 2007; Nduka, et al., 2010). Due to high chances of crude oil spills in the environment, appropriate methods of analysis and predictions of dynamics and diffusion of oil slicks is inevitable.
The changing in concentration in space because of velocity changes is known as
‗‗spreading‘‘. Spreading is one of the most significant processes occurring during oil spill upon water. The practical movement and spill concentration changes with time, as well as the movement rates and the changes are affected by number of environmental variables, together with the physical and chemical properties inherent to the oil itself, (Susu & Abowei, 1998; Boufadel, 2005; Peishi & Williams, 2010.).
Fig 1.1: Niger Delta Coastal line (Nduka, et al., 2010).
Spreading elevates the overall spill slicks surface area. The principal factors influencing spreading are: volume of the oil spilled, gravity, surface tension, inertia and environmental conditions like wind.
Oil spillage can cause pollution. Pollution is the adulteration of the environment by waste matter directly or indirectly, resulting in certain havocs to persons and/or, the surroundings (Nelson & Grubesic, (2018); Marinho, 2011; Peishi & Williams, 2010).
Pollution therefore are as a results of waste matters generated by human daily activities. These waste may be gaseous or particulate emissions, aqueous effluents, solid wastes or in the form of harmful radiation, heat, vibration or noise, (Adegoke, 2013).
In numerous ship vessel tankers or offshore oil wells spills, part of the initial spilled oils caught fire and were combusted. Combustion of crude oils causes emission of gases such as CO2, SOx and NOx into the atmosphere and add to global warming, acid rains and huge amounts of toxic ash. The toxic ash consisting of microscopic particles that could move hundreds of kilometres. Humans Inhalation of these substances could cause allergic reactions which leads to health challenges like sore throats and breathing related issues. (Berry, 2011; Adegoke, 2013)
The more volatile components of the crude oil evaporate at elevated temperature into the atmosphere where they react to form greenhouse and acid gases like those of crude oil combustion products. The adverse effects of either combusted or evaporated oil are more than those of oil that remained onshore, although they equally create reasonable harms to the ecosystem, (Berry, 2011).
Great percentage of the spilled oils mixes with water to produce a substance known as mousse, which could wash up on shore or percolate deep into water body of the environment. A thick tar-form mass which has the capacity to damage the organisms inhabiting in the bottom of oceans were formed as mixture of oil and other sediments in the sea. The tar-form substances could equally move with tides and currents, and wash up on beaches in locations outside spillage area, (Hung, 2013).
1.2 Problem Statement
Several expressions are available in literature for predicting the spread of crude oil on water in laminar flow conditions. In-depth review of these models, show that the model of Fay, (1969), give better prediction of extent of spread, (Ayuba, 2012).
Even though Fay‘s model has a velocity term, it represents the spreading velocity in the absence of some important local climatic factors such as, temperature, wind and tide. The model of Susu & Abowei, (1998) did not incorporate any velocity term in it and applied to swampy conditions. The effects of temperature were not considered in the model.
In the Niger-Delta coastal line local climate conditions are far from being stagnant, due to the influence of wind and temperature variation. A computer simulated model built on oil practical features such as volume of oil discharged, spreading rate and sea properties like viscosity, density, surface tension, as well as the effect of wind, tidal currents and temperature is needed to predict the rate of oil with high accuracy.
1.3 Objectives of Study.
The main objective of this research is to modify the existing model of Abowei & Susu by incorporating Wind and Temperature effects on the spread of Crude oil Spill on Niger Delta Coastal line.
The specific objectives include the following:
- To develop models for spreading coefficient and spreading rate.
- To establish the dependence of spreading coefficient, forces of adhesion and cohesion on surface tension and viscosity of fluid
- To carry out correlation of numerical model resulting to Susu &
Abowei‘s model. iv. To develop a mathematical model that improves the Susu & Abowei‘s model.
- To carry out model validation.
1.4 Justification for the Study
The Niger Delta coastal line is one of Nigeria‘s richest and largest navigation corridors, characterized by windy and temperature conditions, such that with possibility of any oil spill, catastrophic environmental degradation will occur. Oil spill simulation expressions are employed as instrument for impact evaluations on environment, oil spill response and contingency planning. The estimation of slick is achievable so long as the needed information are available. This work is important because the model to be produced can predict more accurately the spread rate of oil spill on Niger Delta coastal line.
Providing further justification for this research work stemmed solely from the outcome of the literature review in this circumstance. From the review, the methodologies employed by previous studies did not account for the effect of temperature, metrological and other environmental conditions such as wind.
The previous researchers based their studies on laminar spread condition.
This research work has essential in acquiring methods to respond and handle challenges of oil spillage on Niger delta coastal line.
1.5 Scope of Study
This research is focused on oil spillage and oil spread on the Niger Delta coastal line, where wind and temperature are considered. The study is limited on open channel flow without any vegetation; it is not extended to swampy terrain.
Although classical expressions of spreading derived by Fay is foundation of most spreading algorithms employed nowadays, it is generally noted that oil spreading cannot be absolutely described by those equations. The degree of data utilized in this work is restricted to already existing data acquired from petroleum companies within and, Susu & Abowei‘s work.
A MODEL INCORPORATING WIND AND TEMPERATURE EFFECTS ON THE SPREAD OF CRUDE OIL SPILL ON NIGER DELTA COASTAL LINE
