Traditional transient well test analysis has been largely based on draw down solution, which works for the reservoir engineering problems of isothermal, uniform and single phase flow in porous media. After so many years of efforts on multi-phase flow approach, methods such as pseudo-pressure approach has been limited. Numerical well testing approach for multi-phase flow problems is the only method currently under further investigation. Presented in this study are three analytical approaches. (1) Statistical pressure derivative which utilises the 2nd differencing of pressure and time series since pressure change and subsurface flow rate are non stationary series, then integrates the residual of its 1st differences using simple statistical functions such as sum of square error SSE, standard deviation, moving average MA and covariance of these series to formulate the model. (2) Pressure-density equivalent algorithm for each fluid phase, which is derived from the fundamental pressure-density relationship and its derivatives used for diagnosing flow regimes and calculating permeability. (3) Density transient analytical DTA solution derived with the same assumptions as (2) above, but the density derivatives for each fluid phase are used along with the semi-log density versus time plot to derive permeability for each fluid phase. (2) and (3) are solutions for multi-phase flow problems when the fluid density is treated as a function of pressure with slight change in density. The first method demonstrated that for high water production well, a good radial stabilization can be identified for good permeability estimation without smoothing the data. Also it showed that in cases investigated, the drawdown fingerprint can be replicated in the build-up pressure response, hence a good match of the data and a better radial flow diagnosis. The second and third methods can, not only derived each individual phase permeability, the derivative response from each phase is visualised to give much clearer picture of the true reservoir response, which in return ensures that the derived permeability originates from the formation radial flow. These approaches were tested with synthetic and field data. The synthetic studies demonstrated that the calculated numerical density derivatives on the diagnostic plot yield much clearer reservoir radial flow regime and give more confident formation permeability estimation. The study also discovered that in the cases investigated, the heavier the fluid such as water, the better permeability estimation from the weighted average pressure-density equivalent derivatives. In order to support further field application of this approach, field data sets were identified and analysed using the developed methods. In this case, the conventional pressure derivative diagnostic method failed to identify the radial flow, hence unable to estimate the reservoir permeability. In contrast, the three methods: statistical pressure, fluid phase numerical density and pressure-density equivalent derivatives gave very clear radial flow stabilizations on the diagnostic plot, from which the reservoir permeability was derived, which matched the up scaled core permeability from the same formation. The presented approaches provide an estimation of the individual fluid phase and formation effective permeabilities, reflecting the contribution of each phase to flow at a given point.

Three-phase flow occurs in petroleum reservoirs during tertiary enhanced oil recovery processes such as water-alternating-gas flooding (WAG). WAG process is used to improve the efficiency of gas flooding by controlling gas mobility. Water traps gas in the reservoir when injected alternatively in WAG. Continuous gas trapping causes a blocking effect that prevents the oil from being contacted by the water. Surfactants are introduced in WAG processes to decrease this water blocking effect and improve oil recovery. This technique of introducing surfactant in WAG processes is known as surfactant-alternating-gas flooding (SAG). One of the important parameters to accurately model complex processes such as SAG is the relative permeability to each of the flowing fluids. However, relative permeability in SAG processes become extremely complicated due to different flow mechanisms and fluid interactions involved. Several researches in the open literature are based on three-phase relative permeability in WAG using three-phase empirical correlations for prediction. Few researchers have conducted experiments on SAG flooding, but their research focused on the aspect of oil recovery only. The aim of this research project is to obtain a better understanding of surfactant interaction in three-phase flow. To do so, a surfactant formulation compatible with the oil and brine was selected by conducting aqueous stability test, surfactant phase behaviour and surfactant adsorption experiments. Water/oil interfacial tension was measured to determine the initial interfacial tension before surfactant injection. Surfactant/oil interfacial tension was calculated using Huh’s correlation. This was followed by two and three-phase core flooding experiments. The results showed that alcohol alkoxy sulphate and internal olefin surfactant blend is most suitable formulation compatible with the brine and oil by reducing water/oil interfacial tension from 22.7 mN/m to 1 x 10- ³ mN/m and having very low adsorption of 0.00135 mg/g adsorption on the core sample. Two-phase water/oil, gas/oil and gas/water experiments were conducted with and without surfactants to evaluate the effect of surfactants when only two fluids are present in the porous media. Sigmund and McCaffery correlation was used in Sendra software to history match experimental differential pressure and oil production data to obtain relative permeability curves. The results showed that in water/oil displacement experiment, the presence of surfactant increases oil relative permeability but did not have any effect on water relative permeability. The cross point of the relative permeability curves moved further to the right indicating that surfactant increases the water wetness of the core sample causing oil to flow freely. Oil production increased in the presence of surfactant, this increase in oil production is because of the reduction in water/oil interfacial tension and decrease in pressure gradient during the experiment. There was an increase in oil production and oil relative permeability also in gas/oil displacement experiment in the presence of surfactant when compared to gas/oil displacement experiment without surfactant. While in gas/water displacement experiment, a significant decrease in gas relative permeability occurred in the presence of surfactant when compared to gas/water displacement experiment with no surfactant. To study surfactant effect on three-phase relative permeability, WAG and SAG core flooding experiments were conducted. The extension of JBN/Welge theory by Grader and O’Meara was applied to calculate three phase relative permeability. Eclipse reservoir simulation software was used to simulate surfactant WAG to predict surfactant effect on three-phase relative permeability using the three-phase correlations such as Stone 1, Stone 2, saturated weighted interpolation, linear interpolation and Stone exponent present in the software. Results from three-phase displacement experiments showed that the presence of surfactant does not have any effect on water relative permeability in three-phase flow. Oil relative permeability was affected by the presence of surfactant and gas. Oil relative permeability and recovery factor were higher in SAG when compared to WAG. In three-phase flow, gas relative permeability was lower in SAG compared to WAG. Gas breakthrough in the presence surfactant occurred at 0.48pore volume while in WAG breakthrough occurred at 0.34 pore volume. The decrease in gas relative permeability was because of foam creation with gas interaction with the surfactant. None of the three-phase relative permeability correlations could accurately predict the effect surfactant on three-phase relative permeability in WAG.

Approximately half of the world oil production is a result of water flooding. A major concern in this process is the mobility control of the injected phase with unfavourable fluid mobility ratio, channelling through permeable zones and, fingering effects can occur leading to an early water breakthrough and an inefficient flooding. Technically, it is possible to improve the flooding efficiency by applying enhanced oil recovery (EOR) processes (e.g. polymer flooding, steam injection and surfactant flooding). EOR processes intend to improve the sweep efficiency by reducing the mobility ratio between injected and in-situ fluids and/or to improve the displacement efficiency by reducing the capillary and interfacial forces. Polymer flooding is an enhanced water flooding process in which the water/oil mobility ratio is lowered by adding watersoluble polymers to water to increase its viscosity. The most applied polymer for EOR processes is the synthetic partially hydrolyzed polyacrylamide (HPAM). Several field projects have been carried out utilising HPAM, and the observed trend is that these polymers show low shear stress stability, and low salt tolerance. They are also sensitive to elevated reservoir temperature. Additionally, polymer retention and adsorption affect the rheological properties of the polymer solution significantly and reduce permeability. Therefore, polymers with greater salinity resilient and temperature resistance are needed. Hydrophobically modified polyacrylamide is a type of associative polymers that has been introduced to oil field applications as an alternative to HPAM for the past two decades. The main characteristics of these polymers are their significant enhancement of water viscosity compared with the conventional polymers such as HPAM, and their salinity tolerance and temperature resistance that would be more important in the real application. In this project, phenyl-polyacrylamide (PPAM), a hydrophobically modified polyacrylamide is studied as a potential viscosifier in waterflooding process. PPAM is synthesised by free radical micellar copolymerisation. The synthesised copolymer was characterised and the polymer composition was determined. Viscosity average molecular weight of copolymer was measured, and the rheological behaviour of the polymer was investigated in both, distilled water and NaCl solution and the results were compared with those obtained for HPAM. Greater viscosity values were observed for PPAM in distilled water and saline brine than HPAM. Comparative flow experiments for polymer solutions were carried out in sand packs to investigate the interaction of polymer, sand, and brine, and also to study the effect of the shear rate on viscosity of the polymer in-situ. The polymer solutions exhibited a shear thinning, shear thickening and degradation behaviour at different shear rates. The experiments were further carried out to investigate the polymer retention at different polymer concentrations, and brine salinity, and the results were compared with those from conventional hydrolysed polyacrylamide. Greater polymer adsorption was observed at higher brine salinity for HPAM than PPAM, however, polymer adsorption for PPAM is slightly greater than HPAM in distilled water. Oil displacement tests were further conducted through consolidated core samples (Benthemier sandstone). The reduction of permeability to water was estimated, and oil recovery was measured. A greater permeability reduction to water was observed for PPAM than HPAM solution at low salinity which is not desirable, however, oil recovery at higher concentration of PPAM was greater than HPAM. In summary, PPAM can be used as a good alternative to conventional HPAM due to strong viscosity behaviour in high salinity and temperature. Intermolecular association of hydrophobic monomers in copolymers of PPAM form a bulky structure which causes great viscosity enhancement of polymer solution in distilled water. PPAM solubility in high salinity water is proven to be greater than HPAM and the results from polymer precipitation tests showed much less polymer precipitation for PPAM than HPAM in high saline brine. Moreover, the results for temperature effect on polymer viscosity demonstrated stronger temperature resistance for PPAM than HPAM.

Silicon based solar cells are the dominant photovoltaic (PV) technology worldwide, but like any technology they must be subject to regular development to maintain this position. The refinement of raw silicon is an expensive process and significant cost reductions are achievable by reducing the bulk material usage. An indirect band-gap semiconductor, silicon is an inefficient absorber of light; therefore light trapping and absorption enhancing schemes are necessary to permit effective reduction in material usage. This is described as making the material optically thick but physically thin. A common approach to this problem is the fabrication of nano and micro-scale rod-like structures on the surface of thin silicon devices which decouple the optical absorption length from the electronic carrier collection distance. This has the added benefit of reducing the material quality requirement which is typically difficult to maintain for thin silicon as it would likely be deposited as a polycrystalline film rather than utilising conventional single crystal or multicrystalline wafers. This project investigates the fabrication and performance of rod-like PV structures which have diameters on the low micron scale (1 μm and 10 μm). The design and fabrication of the structures is described together with results on their optical properties. These demonstrate an average reduction in reflection, compared to planar silicon, of 40% for the 1 μm diameter features and 10-20% for the 10 μm diameter features. Various rod configurations were modelled optically by finite difference time domain (FDTD) simulations and comparisons of the modelled and measured reflection are presented. The results demonstrate good correlation and lend confidence to the use of modelling to inform the design of future structuring schemes. This was believed to be the first systematic study of identical geometry modelled and fabricated devices, particularly on the micron scale. Proximity rapid thermal diffusion (PRTD) is developed as a doping technique and applied for emitter formation. It is believed that this is the first time that this process has been used in conjunction with structured devices for PV purposes. This approach permitted the formation of n-type emitters as shallow as ≈ 200 nm, with a diffusion time of less than three minutes and without the use of toxic process gases or diffusion specific hardware. Work undertaken to optimise the emitter formation process is described and results are presented which support the premise that whilst good absorption is clearly important in a solar cell, without an effective emitter, good efficiencies will remain out of reach. Devices featuring 1 μm diameter rods confirmed this, proving challenging to form effective emitter layers on and were limited to matching planar device performance (conversion efficiency of 5.63% vs 5.64% for the planar control). Whilst subsequent refinement of the emitter diffusion process demonstrated the potential to exceed planar performance, it reiterated the challenging nature of fabricating effective electronic devices involving features on this scale. Conversely, devices with 10 μm diameter rods, whilst exhibiting more modest absorption improvements over equivalent planar devices, ultimately achieved peak efficiencies of 7.68%, a slightly greater than 2% absolute increase over their planar counterparts. The open circuit voltage (Voc) of all devices with length-diameter aspect ratios of 1:1 was found to be in the region 10-20 mV higher than that of a planar control device, whilst devices with 2:1 aspect ratio exhibited Voc values which were broadly comparable to the control. This was generally contradictory to the literature which commonly reports Voc reductions of 10-50 mV for devices with increased surface area compared to planar. The development of various cell contacting schemes is discussed with a particular focus on aluminium doped zinc oxide (AZO), a transparent conductive oxide (TCO). In addition to the expected electronic properties, the sputter deposited films were found to possess useful antireflective performance. Results are presented for conformal coatings of AZO applied to rod structures, with 50-60% reduction in reflection demonstrated over planar silicon for 10 μm diameter rods and over 70% for 1 μm diameter features.

This study investigated the e-Government initiatives in developing countries and analysed Bahrain’s government stance through a case study where the e-Government system is considered as a core strategy. This research therefore sought to address citizens and expatriates' adoption of e-Government services in Bahrain as one of developing countries, which has spent millions of dollars to launch the e-Government initiative, in order to meet the strategic objectives of Bahrain’s government vision 2030. The study included an empirical study using exploratory method to comprehend how citizens/expatriates of Bahrain accept the e-Government service, and evaluated the factors influenced users to adopt this new technology (i.e. e-Service). The research also examined the two aspects of the e-Government services and their stakeholders, including users and service providers. Through a descriptive study, this qualitative case study methodology was conducted via an interview with a key official in the e-Government authority in Bahrain, and the focus group with four specialists in e-Government systems, to determine the e-Government’s usability from the implementation aspects. The quantitative method, on the other hand, was implemented through questionnaires with both citizens and expatriates to determine the e-Government’s usability from the adoption aspects in Bahrain. The extended technology acceptance model (TAM) was used as predictive modelling and a technique for analysing results of the user survey. The newly developed conceptual model via a structural analysis indicated that citizens and expatriates in Bahrain are willing to accept and use the e-Government system, and it is the most determinant methods of peoples' intention with the system. However, the research indicated there are some issues related to the trust and cultural constructs that need to be addressed by the government based on the attitude of citizens and expatriates determined toward Behaviour Intention (BI) directly, and through the perceived usefulness and ease of use. The research indicated the common factors influence e-Government's adoption from both demand and supply aspects in Bahrain, and the best solutions proposed by the respondents. The conclusion of this study based on the findings comprised of a conceptual framework that explained why the citizens and expatriates' adoption of e-Government services as the core strategic enabler to Bahrain's vision 2030.

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