In the petroleum industry, cyclonic separators are acceptable as hydrocyclone, mist eliminators, separator internal device and compact metering package. Weight and small footprint requirements for applications such as subsea separation, downhole separation, and compact gas monetization systems is driving interest in using cyclonic separator for bulk gas-liquid separation. Unfortunately, the challenge of coping with the effect of unsteady inlet flow behaviour on the separator performance limit it acceptance for bulk gas-liquid separation. Fundamental understanding of the flow behaviour inside the separator under various inlet flow conditions is required to deal with the challenge. While most published work have addressed flow behaviour in the lower half of cyclonic separator, this thesis concentrated on the upper half. A gas-liquid pipe cyclonic separator was setup at Cranfield University for bulk gas-liquid separation. Large amount of data at the inlet and upper part of the separator were acquired using electrical resistance tomography (ERT), wire meshes sensor (WMS), conductivity hold up probe and pressure transducers. The acquired data were used in analysing flow regimes, upward swirling liquid film (USLF), zero-net liquid flow (ZNLF), liquid holdup and, general separator performance. It was found from analysis of USLF data that a maximum USLF height exists for every constant superficial liquid velocity. A correlation based on dimensionless numbers was proposed for predicting this height. Experimental results on ZNLF showed that a critical ZNLF also exist above which liquid carryover can take place. The liquid holdup for this critical ZNLF was measured under separator operating condition using ERT and a correlation for predicting the liquid holdup was proposed. Four flow regimes were identified as swirling annular, light-mist heavy-mist and churn using visual observations, ERT, WMS and pressure transducer. A flow regime map was proposed based on gas and liquid Froude number. The performance based on the operating envelope for liquid carryover and pressure drop for horizontal and 270 downward inclined tangential inlet was compared. It was concluded that the separation performance was marginally improved by using an inclined tangential inlet. The pressure drop for the inclined inlet was far greater than that of horizontal inlet. Two inlet nozzles with D–shape were used for separation enhancement. The nozzle that reduces the diameter of full pipe bore by 25% gave slight improvement but also gave the greatest pressure drop. The nozzle that reduced the full pipe bore diameter by 50% performed poorly.

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In view of current interest in geological CO2 sequestration and EOR, this study investigated water-based and gas-based CO2 injection strategies for coupled EOR and storage purposes. For water-based CO2 injection strategy, carbonated water injection (CWI) was investigated as an alternative injection mode that could improve sweep efficiency and provide safe storage of CO2. Despite its potential, CWI has not been very much studied. This thesis presents the details on the performance of CWI of moderately viscous oil (>100 cP), which has not been reported before. The effects of oil viscosity, rock wettability and brine salinity on oil recovery from CWI were also studied and significant findings were observed. To the author’s knowledge, no attempt has been made to experimentally quantify the CO2 storage by CWI process and to model the nonequilibrium effects in the CWI at the core scale using the commercial reservoir simulators. These are amongst the main innovative aspects of this thesis. The experimental results reveal that CWI under both secondary and tertiary recovery modes increase oil recovery and CO2 storage with higher potential when using light oil, low salinity carbonated brine and mixed-wet core. In this study, the compositional simulator overpredicts the oil recovery. The instantaneous equilibrium and complete mixing assumptions appear to be inappropriate, where local equilibrium was not in fact achieved during the CW process at this scale. The author evaluated the use of the transport coefficient (the a-factor) to account for the dispersive mixing effects, and found that the approach gives a more accurate prediction of the CWI process. For the gas-based CO2 injection strategies, a practical yet comprehensive approach using reservoir simulation, Design of Experiment (DOE) and the Response Surface Model (RSM) to screen for and co-optimize the most technically and economically promising injection strategy for coupled EOR and CO2 storage is presented. For the reservoir model used in this study, miscible WAG was found to be most economically promising, while miscible continuous CO2 injection was ranked as the most technically viable. The duration of the preceding waterflood, relative permeability (wettability) and injected gas composition are the three most significant factors to the profitability of oil recovery and CO2 storage through tertiary WAG injection.

Sand production is a complex problem that has plagued the oil and gas industry for decades, leading to reduced productivity, wellbore instability, equipment failure and expensive sand control and management techniques. Therefore, a reliable prediction of the potential of a formation to produce sand as well as the mass and volume of the sand produced is required for an appropriate and economically effective sand management. In this thesis a novel approach (yield energy model) to predict the potential of formation to produce sand and to quantify the mass of sand produced around yielded wellbore region based on energy dissipation is presented. During drilling and hydrocarbon production, yield and fragmentation of rock around a wellbore may occur when the rock is exposed to stresses which exceed its failure criterion, creating yield zone and hence the potential for instability and sand production. Generally, in brittle rocks, grains are deformed elastically with increasing stress, storing strain energy in the process. The stored strain energy is dissipated during failure, some of which is available for the fragmentation of the rock along failure surfaces. It is argued that the major source of sand production in competent rock is associated with the debris created by slippage along shear fractures in the yielded zone along perforation wall. The potential for sand production and the mass or volume of the sand created around the yield zone is predicted by quantifying the reduction in strain energy stored in the rock as its yields around a completion on removal of completion fluid and the imposition of drawdown. The resultant sand then becomes available as a source for sand production. The yield energy model has been applied to assess the potential of several reservoir samples to produce sand and also quantify the mass of the sand produced as a result of formation instability caused by drilling and hydrocarbon production in a field specific manner. Results from laboratory testing of representative samples and field data has been utilised as input parameters. The extent of the failed zone, the sand production potential and the mass of debris have been analysed as a function of mud weights, drawdown pressures and production rates. The impact of unique production performance of different horizons on formation stability has been accounted for by employing deliverability expressions. The results have been assessed with regards to field observations and were found to be consistent.

Recent attempts to utilise solid particles in combination with high pressure water sprays has caused environmental and safety concern, in cleaning mineral and organic scale inside the Oil and Gas Production Tubing. To increase cleaning performance only high pressure aerated water sprays at high impact force instead should be used. Multi-nationals petroleum companies are facing immense challenges in removing the scale due to the decrease in cavitation bubbles along the production tubing when high pressure water sprays are applied. This has also resulted in high maintenance costs and low productivity of the ‘wells’ with multi billions pounds financial losses per annum. Currently scales are removed using either aggressive chemicals (acids), complete replacement of the tubing, or solid-liquid sprays which are both expensive and causes environmental concern. This research demonstrated that the application of air-water combination (aerated sprays) are the solution in complete removal of various scales in the production tubing without the use of solid particles and the cavitation bubbles. This novel experimental technique of scale removal utilised air concentration (or aeration) in combination with high pressure flat fan sprays, of up to 10 MPa, at low flow rate (up to 12 l/min) with high impact pressure of approximately 0.15 MPa, in removing scale along production tubing using a simulated aeration chamber. It was found that varying air concentration from 3 to 12%, within the emulated chamber, improved scale erosion up to 28% higher than non-aerated technique. This enabled the mass of the scale to be removed at the ‘stand-off distance’ of 25 mm relative to scale samples, irrespective of cavitation bubble length suppression which is normally about 2 mm away from the atomiser orifice exit, compared to non-aerated techniques (solids and water). Scale erosion was found to be 12.80g, 7.31 g, and 65.80 g at aerated conditions compared to non-aerated provision which found to be 9.88g, 6.33g and 5.31 g, at the required liquid pressure 10 MPa, for the hard, medium and soft scale samples that are typically found in oil production tubing. Prior to scale removal trials sprays were characterised qualitatively and quantitatively under the ambient conditions as well as inside the aerated simulated chamber. Air velocities were found to be approximately 18m/s towards the water spray centre which then decays to 3 m/s towards the spray periphery under ambient conditions using hot wire anemometer. Moreover, the flat fan sprays were also characterised utilising Phase Doppler Anemometry (PDA). It was found that the high pressure water liquid droplet velocities were in the range of 75 to 117 m/s with droplet diameters of 55 to 81 µm (SMD) at flow rates of 7.6 to 11.3 l/min at various stand-off distances of 25, 50 and 75mm, providing an impact pressure of 0.05, 0.10 and 0.15 MPa respectively. Qualitatively cavitation bubble length was also estimated using high resolution imaging techniques which were found to be between 1 to 2 mm from the atomiser exit orifice under submerged conditions, at the stand-off distance ≤ 25 mm where the scale is normally removed. Beyond this range (1-2 mm) where the cavitation bubbles are not present, that are normally the benefactors to scale removal process, requires air concentration up to 12%. This ensures that a complete removal of the mass of corresponding scales to be achieved with varying chemical scale compositions. The air concentration is the ratio of total mass of air within the simulated chamber to mass of the liquid sprays impacting directly onto the scale samples. The results of the experimental trials were used to validate the available CFD fluent models with regards to spray dynamics, aerated air (velocities), cavitation bubble generations and scale erosion (removal). The sensitivity analysis using the CFD modelling gave close comparison with those obtained through experimental trials. Spray droplets size and their velocities were found to be within ±10% compared to those obtained via experimental findings. The aerated air velocities were also compared with the data generated from CFD which were found to be approximately ±9%. Furthermore, the cavitation bubble generation and the mass of the scale removed were found to vary within ±5% and ±7% respectively, when compared to the CFD data. Finding emerged that the spray droplets especially at the centre undergoes acceleration after primary breakup, which due to higher velocities resulting from the acceleration has left the entrained-air particles behind, which is characterise with substantially low-pressure region, giving rise to utilisation of the air-water interaction model. This could be another approach in further understanding the break regions within the high pressure liquid sprays.

This thesis describes the identification of chemical species responsible for sediment formation during storage of an unstable diesel fuel. It is currently not possible to reliably predict the storage stability characteristics of diesel fuels, ie. to distinguish between stable diesel fuels, which remain chemically and physically unchanged during storage, and unstable fuels, which deteriorate under the same conditions to produce insoluble sediment. This study was carried out in order to assist with the development of chemical tests to predict diesel fuel storage stability characteristics. An unstable diesel fuel was stored under ambient conditions for two years. The sediment produced during this period was collected and analysed by TLC, IR, MS, pyrolysis/MS and pyrolysis/GC/MS. Alkyl derivatives of indole were found to be important constituents of the sediment. The diesel fuel itself was analysed using LC, GC, TLC and MS. Alkylindoles and compounds, confirmed by synthesis to be alkyl derivatives of indolylphenalene and bis(indolyl)phenalene, were detected in the fuel. It has been shown that indolylphenalenes and bis(indolyl)phenalenes are converted by acid into material whose analytical characteristics are almost identical to those of a major constituent of sediment. Phenalenone and alkylphenalenones have also been detected in the fuel. These compounds are thought to arise in fuel from autooxidation of the corresponding phenalenes. The observed increase in concentration of indolylphenalenes and bis(indolyl)phenalenes during fuel storage was attributed to reaction of alkylindoles with phenalenone and alkylphenalenones. Addition of phenalene and 2-methylindole to an otherwise stable fuel, followed by storage for 6 months at 25°C, resulted in the formation of phenalenone, 2-methylindolylphenalene, bis(2-methlyindolyl)phenalene and sediment, with analytical characteristics consistent with those of sediment formed during storage of the unstable fuel. It is concluded that sediment formation in the unstable fuel was caused by acid promoted reactions of alkylindoles with phenalenones.

The results of numerical study of heating and evaporation of monodisperse fuel droplets in an ambient air of fixed temperature and atmospheric pressure are reported and compared to experimental data from the literature. The numerical model is based on the Effective Thermal Conductivity (ETC) model and the analytical solution to the heat conduction equation inside droplets. It is pointed out that the interactions between droplets lead to noticeable reduction of their heating in the case of ethanol, 3-pentanone, n-heptane, n-decane and n-dodecane droplets, and reduction of their cooling in the case of acetone. A simplified model for bi- component droplet heating and evaporation is developed. The predicted time evolution of the average temperatures is shown to be reasonably close to the measured one (ethanol/acetone mixture). The above-mentioned simplified model is generalised to take into account the coupling between droplets and the ambient gas. The model is applied to the analysis of the experimentally observed heating and evaporation of a monodispersed n-decane/3-pentanone mixture of droplets at atmospheric pressure. It is pointed out that the number of terms in the series in the expressions for droplet temperature and species mass fractions can be reduced to as few as three, with possible errors less than about 0.5%. In this case, the model can be recommended for implementation into CFD codes. The simplified model for bi- component droplet heating and evaporation, based on the analytical solutions to the heat transfer and species diffusion equations, is generalised to take into account the effect of the moving boundary and its predictions are compared with those of the model based on the numerical solutions to the heat transfer and species diffusion equations for both moving and stationary boundary conditions. A new model for heating and evaporation of complex multi-component hydrocarbons fuel droplets is developed and applied to Diesel and gasoline fuels. In contrast to all previous models for multi-component fuel droplets with large number of components, the new model takes into account the effects of thermal diffusion and diffusion of components within the droplets.

The body of work presented here is focussed on five published papers which address solving inorganic scale problems experienced by the North Sea oil industry with a focus on the Norwegian Continential Shelf (NCS) over the last ten years or so. The degree of increasing difficulty in addressing issues of serious barium sulphate scaling, in the reservoir and wellbore areas, complicated by seawater breakthrough, the authorities demand for improvement in environmental properties of the chemistries deployed, the cost driven push for longer treatment life and with the increasing awareness of the damaging effects of deploying water based scale inhibitors into water sensitive reservoirs, is described in detail. The work focuses on industry developed laboratory test methods, synthesising novel chemistries and developing improved deployment designs as a means of solving these significant problems. The work is not a pure chemistry programme, it is an applied chemistry study focused on solving reallife oilfield scale problems. The project(s), planning and strategy involved leveraging knowledge and input from across the disciplines of production chemistry, petroleum engineering and near wellbore region modelling. It should be noted the real driver for the work was the inability of the available commercialised chemistries to resolve the problems. The resultant loss of production and associated remedial treatments were of a significant financial and environmental cost to the industry. The papers cover the design testing and deployment of co-polymers and terpolymers to produce innovative molecules which offer higher performance scale inhibition and life of treatments in actively producing oil wells. The new molecules meet the environmental requirements of biodegradation, bioaccumulation and toxicity. The projects offered are under the following headings:  Enhanced inhibitor squeeze treatment life through "Bridging"  Field experiences in Application of Inhibitor Interactive Packages Resulting in Increased Squeeze Life.  Development of multi-functional chemicals for efficient "fines" control and squeeze life enhancement in producing oil wells.  Development of highly efficient and environmentally friendly scale inhibitor molecules for oilfield use, including reference to more efficient placement technology.  Oil soluble scale inhibitor development. The papers describe synthesis, laboratory testing and field deployment experiments leading to adoption of the new technology by multi-national oil companies. In most cases patents have also been granted. The value added of the work is also quantified in both environmental and financial aspects.

Persistent whole-plant disturbances can have an especially large impact on product quality and running costs. There is thus a motivation for the automated detection of a plant-wide disturbance and for the isolation of its sources. Oscillations increase variability and can prevent a plant from operating close to optimal constraints. They can also camouflage other behaviour that may need attention such as upsets due to external disturbances. A large petrochemical plant may have a 1000 or more control loops and indicators, so a key requirement of an industrial control engineer is for an automated means to detect and isolate the root cause of these oscillations so that maintenance effort can be directed efficiently. The propagation model that is proposed is represented by a log-ratio plot, which is shown to be ‘bell’ shaped in most industrial situations. Theoretical and practical issues are addressed to derive guidelines for determining the cut-off frequencies of the ‘bell’ from data sets requiring little knowledge of the plant schematic and controller settings. The alternative method for isolation is based on the bispectrum and makes explicit use of this model representation. A comparison is then made with other techniques. These techniques include nonlinear time series analysis tools like Correlation dimension and maximal Lyapunov Exponent and a new interpretation of the Spectral ICA method, which is proposed to accommodate our revised understanding of harmonic propagation. Both simulated and real plant data are used to test the proposed approaches. Results demonstrate and compare their ability to detect and isolate the root cause of whole plant oscillations. Being based on higher order statistics (HOS), the bispectrum also provides a means to detect nonlinearity when oscillatory measurement records exist in process systems. Its comparison with previous HOS based nonlinearity detection method is made and the bispectrum-based is preferred.

In recent years, petrochemicals products from Saudi Arabia have been the subject of anti-dumping (AD) cases in several countries. This has raised questions about whether Saudi Arabia’s domestic laws and regulations relating to AD and anti-subsidy are, (1) effective, and (2) compatible with Saudi Arabia’s international legal obligations under the World Trade Organisation (WTO). This thesis examines the compatibility of Saudi Arabia’s domestic laws concerning AD, with international trade law, under the WTO agreement on the Implementation of Article VI of the General Agreement on Tariffs and Trade 1994 (Anti-Dumping Agreement (AD Agreement)). It critically analyses cases filed against Saudi Arabia’s petrochemicals products in a number of countries; including India, China, and Turkey, and in the European Union. It is observed that the high number of AD cases filed against Saudi Arabia’s petrochemicals products around the world reflect a need to strengthen Saudi Arabia’s domestic laws, and the regulations applicable to dumping. Arguably, some aspects of the WTO AD Agreement are in need of reconsideration by the contracting parties in view of the modern context of trade between contracting parties. Aspects to be re-examined include, for example, dispute resolution procedures. In this respect, this thesis argues that some parts of the WTO AD Agreement should be subject to further negotiations between the WTO contracting parties, with a view to making appropriate amendments. Finally, this research will present recommendations for the Saudi Arabian economic system, suggest amendments relating to AD and anti-subsidy provisions under the WTO and finally offer recommendations for the dispute resolution mechanism under the DSU. This will help to improve and develop an effective AD legal regime under the WTO agreement, which would be applicable in the context of the changing circumstances of global international trade.