Masters Candidate

Thesis Title: Assessing the Hydrocarbon Potential of Offshore Lamu Basin using Nuclear Well Logs

Kenya’s sedimentary basins are similar to other basins in eastern Africa where hydrocarbons have been discovered. The recent discovery of oil in Turkana, a region initially dismissed as non-viable has prompted review of previous data and integration of modern nuclear logging techniques in exploration. The main objective of this study was to use nuclear well log data to assess the hydrocarbon potential in Offshore Lamu basin. The neutron, density, and gamma log data in LAS format for Simba-1, Kofia-1 and Maridadi-1B wells were acquired from National Oil Corporation of Kenya and subjected to well log analysis. The results were integrated with electric log data and cuttings reports for quality control. Essentially, the study determined petrophysical parameters mainly: lithology, volume of shale (Vsh), porosity, and fluid saturation to gauge the hydrocarbon reservoir characteristics of the basin. The results show, on average, three zones of interest in study area ranging between 2600 m-3900 m below mean sea level. Sandstone and limestone are the predicted reservoir formations, while shale is the interpreted source rock. The porosity at the zones of interest is 21% - 35%. The Vsh is lower, estimated at 16% - 24% in projected reservoir zones. Predicted water saturation is high 30% - 60%, and estimated permeability ranges from 21 mD to 116 mD. This results indicate the presence of hydrocarbons in the Lamu basin but whose quantity is undeterminable. The study recommends drilling of directional wells, and the use NMR technique to determine bound fluids.

Research Supervisors

1. Mr. Michael J. Mangala, Institute of Nuclear Science and Technology, University of Nairobi
2. Prof. Jayanti P. Patel, Department of Physics, University of Nairobi

Assessment and Mapping of Black Carbon and PM2.5 Variability: A

case study in Nairobi city.

Airborne particulate matter is of great concern in the global
environment due to associated negative effects on human health and
environment. Air sampling was conducted at nine selected sites within
Nairobi city between 17/05/2016 to 22/06/2016. The mean 8-h PM2.5
concentrations in the selected nine sampling sites for the study ranged
between 147 ± 89 μg m-3 and 52 ± 4 μg m-3

. Mean BC concentration

for the nine sampling sites ranged from 8.6 ± 3.3 μg m-3

to 2.1 ± 1.2

μg m-3
. OLS dispersive models were further used to map out the
pollution levels across the city. Elemental content of the sampled fine
particulates included Cu, Mn, Zn, Fe, Pb, and Zr which were found to
be above detection limits of 50, 1210, 470, 200, 30 and 480 ng m-3
respectively. The detected trace elements accounted for 15 % of the
species in PM2.5, while BC accounted for 8 %.

Assessment of Heavy Metal Pollution Using XRF Spectrometry– A Case Study of Kilimapesa Hill Gold Mines Processing Plant area, Narok County

This study determined the levels of heavy metal concentrations; cadmium, arsenic, chromium, mercury, lead, copper and zinc in environmental samples, to assess the extent of pollution around Kilimapesa. Forty-one samples, from nineteen sites; nine sub-surface soils, eight sediments, fourteen Sodom apple leaves and ten water samples were analysed for heavy metal content using XRF spectrometry.  The concentrations levels in water was highest at the confluence of the streams. The levels in soil samples were high compared to World Health Organization standards. The concentrations in Sodom apple were comparable to those found in undisturbed environments, except for arsenic and lead. A significant difference in metal levels among the three media was observed, following ANOVA analyses. Pearson's correlation for the elements in Sodom apple and soils were very weak except for mercury. The same trend was replicated between soils and water, and between water and plants, for all heavy metals of interest in this study, except for Zn and Ni, respectively. Generally, soils are moderately to extremely contaminated. An introduction of heavy metals bio-accumulators in the waste disposal treatment ponds and enforcement of disposal regulations and for epidemiological studies.

Quantification of Uranium and Thorium at Cheptais Anomaly
Using Energy Dispersive X-Ray Fluorescence Method for
Mineral Content Evaluation and Associated Radio-ecological
Hazards

This study was conducted in Cheptais to determine 232Th and
238U radioactivity levels as a follow up to airborne radiometric
survey previously conducted. The study estimated the
radiological hazard indices associated with the two radionuclides.
It also determined the distribution of potential elemental content
for economic development and the associated environmental
hazards. The radiometric survey was carried out using an ionizing
radiation measuring instrument, RSKB-104. Thirty-six soil
samples and seven rock samples were evaluated for elemental
contents using and EDXRF Spectrometer. Prior to measurements,
the collected samples were crushed, homogenized and left to
achieve secular equilibrium for two months. The major
constituents in the soil samples were found to e K, Fe, Mn, Cu,
Zn, Pb, U and Th. 40K was the greatest contributor to radiation
exposure in the study area. The radiological results were; Ra
equivalent (426 Bq kg-1), gamma radiation index (3.03), and
external and internal hazard indices (1.15 and 1.36 respectively).
The absorbed dose rates due to gamma radiation was 199 nGy h-1
in air at 1 m above the ground level and the annual effective dose
with an outdoor occupancy factor of 0.4 was 0.24 mSv y-1. All
the measured values were all above the required UNSCEAR
limits. Therefore, the radioactivity levels did not pose a
significant risk to the public except at the central area of the study
area where ???? was recorded. The study recommends further

extensive radiological assessment in the area including radio-
ecological analysis in water sources.

Thesis Title: Investigation of the Applicability of Electrohydrodynamic Atomisation in Odorisation in High-Pressure Gas Supply Lines

Electrohydrodynamic atomisation (EHDA) is a viable alternative that can be considered for use in the odorization of natural gas. A suitable nozzle able to operate inside the high-pressure, high velocity environment of gas supply lines was designed and fabricated. However, to implement EHDA odorization in an industrial scale, particularly inside a natural gaspipeline, a suitable monitoring system for determining the operational mode of the electrospray had to be used, since some setups may not readily allow visual access. This was done by designing, building and testing a high voltage probe to measure the electric current flowing in the high voltage line while simultaneously measuring the current flowing in the ground line in EHDA setups. The goal was to finally develop an efficient EHDA system for natural gas odorization that can be reliably monitored using a signal representing the electric current in the system. In the end, a nozzle was fabricated and used in a high-pressure gas pipeline. While EHDA experiments were conducted in a gas pipeline, it was not possible to carry out current measurements in that setup. It is recommended that whenever a need arises to measure currents in EHDA setups, such measurements should be done in the high voltage line as their reliability has been demonstrated in this research. It also emerged that an

EHDA nozzle for use in gas pipelines should be positioned in such a way that it points in the direction of the flow of the gas.

Thesis Title: Electrohydrodynamic Atomization Of Non-Newtonian Liquids With High Solid Content : A Case Study For The Production Of Powder

Electrohydrodynamic atomization (EHDA) is now a well-known technique among researchers as a potential technique for industries. The technique uses electric fields to produce mono-dispersed charged droplets and ensures controlled production. The current work investigated the intrinsic aspects of EHDA atomization of non-Newtonian liquids with high solid content made from infant milk formula (IMF) powder. The aim was to determine the characteristics of sprays of IMF solutions with high solid content, compare them with characteristics of EHDA atomization of Newtonian liquids, and investigate the possibilities of out-scaling. The electrospray characteristics were conducted in the dripping and in the jetting regime using a grounded nozzle and charged counter electrode. The visualization of sprays was done using a high-speed camera with backlight illumination. The obtained modes for solid content less than 40% w/w in the dripping regime were possible to correlate to conventional electrospray modes. The simple jet mode was obtained in the jetting regime with whipping break-up producing smaller droplets compared to varicose break-up. The out-scaling experiments using 55% w/w IMF solution led to the development of a single nozzle with four orifices and each orifice having 300 µm internal diameter. This nozzle configuration achieved a throughput of ~3 L h-1 and droplets with broad size distribution (13 µm ≤ d ≤ 1900 µm). The broad distribution was attributed to the whipping break-up mechanism of the IMF electrospray jets. Further studies are necessary to determine the properties of the powder product that can be obtained when electrospraying in an evaporator.

Comparative Evaluation of the Components of Biogas Digestate Slurries and Effects on Agricultural Soils

This study sought to characterize biogas digester slurries under varying  Feedstocks and provide information useful for assessing the potential impact of their usage as organic fertilizer on crop productivity and environment. The study was informed by the need to allow agricultural scientists determine how individual biogas feeds affect the composition of the final digestate. Digestates from human waste, livestock waste, and abattoir waste feedstock were sampled for the study. The pellets from the samples were then analyzed using Energy Dispersive X-ray Fluoroscopy (EDXRF) spectroscopy for elemental components. Human waste digestate had the highest concentration values for most elements. In human waste, essential elements were determined at 40600 ± 2000, 19000 ± 1140, 1300 ± 400, 200 ± 30, 900 ± 260 ppm for Ca, Fe, Mn, Zn and Cu respectively, as compared to Ca (26400 ± 1400), Fe (9500 ±
440), Mn (820 ± 190), Zn (180 ± 40), Cu (360 ± 70), in livestock waste. In abattoir waste, the mean content was 49500 ± 4100 for Ca, 15220 ± 1350 for Fe, 1090 ± 90 for Mn, 200 ± 50 for Zn and 140 ± 50 for Cu. Pb concentrations were highest in human waste at 20.81 ppm. The high amounts are associated with the micro industrial activities in Kibera. Therefore, human wastes digestates might be the best nutrient supplement but is the most probable threat to environment. For agronomists, crops need matching with digestates from which they would benefit the most, given unique crop requirements.

Evaluation of Effectiveness of Non Destructive Testing Techniques for Inspection of Critical Aircraft Components: A Case of The Kenyan Aviation Industry.

This study evaluated the effectiveness of four types of NDT methods; ultrasonic inspection, radiography, visual testing and magnetic particle inspection being used in aviation industry using aircraft engine and landing gear components to evaluate structural defects during maintenance. This study was motivated by the need to improve our understanding and application of different NDT methods in defect identification in critical aircraft components. 101 aircraft samples were inspected at different NDT Laboratories between July 2017 – April 2019. During this study, the following defects were found; cracks (60%), corrosion (6%), delamination (2%), disbond defects (2%). 29 samples (30%) had no defects. In conclusion, the study identified the structural defects in the aircraft components as; fatigue cracks, corrosion, delamination and disbond defects. The most effective NDT method for use in aircraft routine inspection is boroscopic, with the highest Probability of Detection (POD) at the 95% confidence. Visual inspection by magnifying glass is generally sensitive to larger size defects. MPI method is appropriate in defect detection of both surface and subsurface defects of ferrous materials. The application of UT method was appropriate in detecting subsurface defects. Increasing the frequency of aircraft inspections and further research on corrosion related defects upon approval by Original Equipment Manufacturers are recommended. The results of this study will contribute to improved safety and maintenance that aircraft operate in the tropical climatic conditions hence prone to high rates of wear and tear of components.regime in the aviation industry in Kenya for extended service life considering