Energy, Geoscience, Infrastructure and Society

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3D and 4D inversion for rock and fluid properties using deep learning
(Heriot-Watt University, 2025-04) Lew, Chean Lin; MacBeth, Professor Colin; Elsheikh, Professor Ahmed; Côrte, Doctor Gustavo
This thesis focuses on estimating rock and fluid properties from the perspective of 3D and 4D seismic inversion. I developed two techniques that enable seamless integration of 3D and 4D seismic data. The first technique emphasises the estimation of porosity, Vclay, and hydrocarbon saturation directly from 3D seismic data using deep learning. Additionally, I propose an approach to enhance the lateral continuity of these estimated petrophysical properties. The products from this first technique are subsequently integrated into the 4D domain, leading to the development of the second technique that enables the inversion for reservoir pressure and saturation changes from 4D seismic data using deep learning. Both techniques involve the use of synthetic training datasets for network training, where the detailed processes for building realistic training datasets are presented. The first technique was tested across four fields with diverse deposition environments, covering meandering fluvial systems, fluvial estuaries, deepwater settings, and carbonate platforms. The second technique was applied to the meandering fluvial field with available 4D seismic data. This technique successfully distinguishes pressure effects from saturation-related effects in the 4D seismic response. It also highlights the importance of incorporating fluid flow information into the training dataset, enabling the network to capture the relationship between the superimposed effects of dynamic property changes and the corresponding 4D seismic response. Finally, I present a summary of the cost-benefit analysis of these developed techniques, demonstrating their ability to accelerate the inversion process in terms of turnaround time while providing robust solutions when applied to field applications.
3D printing-based microfluidics for geosciences
(Heriot-Watt University, 2023-08) Patsoukis Dimou, Alexandros; Maes, Doctor Julien; Menke, Dr Hannah; Geiger, Professor Sebastian
Three-dimensional (3D) printing offers the potential to repeatably generate porous media for the investigation of pore-scale processes such as CO2 dissolution and species transport in multiscale porous media. However, there are concerns regarding dimensional fidelity, shape conformity and surface quality of the 3D printed products, and therefore, the printing quality and printer limitations must be benchmarked. Firstly, we investigate the ability to generate porous media with our 3D printing setup. We show that our 3D printing setup allows for cheap and fast fabrication of micromodel devices from simple to complicated multiscale geometries, which enable the ability to perform repeatable single-phase flow species transport experiments. We use Particle Image Velocimetry (PIV) and Direct Numerical simulations (DNS) to show how, with our 3D printing setup, we can generate custom-designed micromodels accurately and repeatably with minimum pore-throat sizes of 140 µm. To enhance the management of subsurface engineering processes in multiscale porous media, containing fractures and matrix, it is crucial to comprehend the interaction between the larger-scale features (fractures) and the smaller-scale features (matrix). While models describing fluid flow in multiscale-porous media exists, it has not been validated experimentally due to lack of a benchmark experimental dataset. In this work we use 3D printing to fabricate geometries that encompass both fractures and matrix. We conduct species transport experiments and generate a benchmark experimental dataset for single-phase flow species transport in multiscale geometries. Our findings demonstrate that 3D printed multiscale micromodels allow for the visualization of species transport propagation in such geometries, enabling the acquisition of a benchmark experimental dataset. Subsequently, we use the acquired experimental dataset and direct numerical simulations (DNS) to validate the multiscale species transport Darcy Brinkman Stokes (DBS) simulations in multiscale geometries containing both fractures and matrix, which have not been previously validated. Our research shows how DBS can accurately predict the temporal evolution of species propagation in these multiscale geometries. Finally, we use simple 3D printed geometries consisting of a single channel and dead-end pores to investigate the trapping and dissolution of CO2 bubbles. Dissolution of CO2 bubbles in the pore-space is an important trapping mechanism during CO2 storage operations, however, a benchmark experimental dataset of dissolution of CO2 bubbles that could validate direct numerical models does not exist. We show that repeatable experiments can be performed in simple geometries and a benchmark experimental dataset for multiphase flow processes can be obtained. As a result, we developed a benchmark experimental dataset for validating DNS models describing the dissolution of trapped CO2 bubbles which have not been before validated against experimental data. Finally, we use DNS simulations and show that while DNS can accurately capture dissolution of a CO2 bubble in simple geometries, such as a dead-end pore and a throat, the current computational requirements do not allow for simulating more complicated cases.
Abandoned housing development : the Malaysian experience
(Heriot-Watt University, 2010-02) Khalid, Mohamad Sukeri; White, Doctor Michael
The issue of abandoned housing project is a matter of grave importance in Malaysia. This study sought to identify the causes leading to the problem from the view point of neo-classical and institutional economic analysis. Having that aim in mind, the research focused on reviewing available literature on the applicability of neo-classical and institutional theories in land and property market analysis, understanding the abandoned housing projects, identifying institution affecting housing development in Malaysia, examining the role of market signal, identifying the causes of abandoned housing projects and recommending suitable policies to prevent and solve the problem of abandoned projects. Extensive field work was done in order to collect primary data for the study. Surveys and semi-structured interviews were done using sample study areas which comprises of 6 different states in Malaysia. The respondents in this study are sample from the population of private developers. Based on the findings, it can be concluded that the cause of abandonment of housing projects relates to institutional factors and failure to respond appropriately to market signal.
Accelerating offshore wind development in Indonesia : a case study of South Sulawesi
(Heriot-Watt University, 2025-03) Susilawati, Dyah Ika; Porter, Professor Joanne S.; Fruh, Doctor Wolf-Gerrit; Hull, Doctor Mark
Abstract and full text unavailable. Restricted access until 29.11.2027. Please refer to PDF.
Accessibility modelling in planning practice : the impact of planned transport infrastructure on accessibility patterns in Edinburgh, UK
(Heriot-Watt University, 2015-03) Karou, Saleem; Hull, Angela; Bramley, Glen
Although many models/tools have recently been developed to measure spatial accessibility, many of these tools are still restricted to academic studies and have barely been applied in the world of planning practice due to several reasons including the complexity or inadequacy of the methodological approaches involved. Within this context, the research undertaken is motivated by the need to translate the concept of accessibility into a practical and useful tool for practitioners and policy makers. The research identifies several omissions in existing accessibility tools that can be considered as potentially important limitations for some purposes in transport and land-use planning. It also investigates the key features that characterise the usefulness of accessibility tools in planning practice. These findings have been used to develop the GIS-based accessibility tool for this research – SNAPTA (Spatial Network Analysis of Public Transport Accessibility) – which attempts to offer better usability and responds to a number of the omissions identified in existing accessibility tools. SNAPTA has been applied to a pilot study in Edinburgh city with the main aim of analysing the contribution of the planned transport interventions to improved accessibility by public transport and distributional benefits for urban services and activities in the city. This research case study presents the first attempt to analyse profoundly the accessibility impacts of possible combinations of implementing future phases of the Edinburgh Tram and the Edinburgh South Suburban Railway (ESSR). The findings provide a better insight into the spatial equity and accessibility levels in Edinburgh, demonstrating the significance of introducing non-radial public transport routes to the city network. A key output of the analysis suggests that the first part of Edinburgh Tram, delivered in summer 2014, would bring a very limited improvement to the accessibility of population across Edinburgh Council‟s area. On the other hand, the empirical evidence of the study shows that ESSR can play a significant role, bringing a greater benefit for accessibility than any other combination of tram lines. A workshop organised to test SNAPTA in a virtually real exercise enabled expert assessment of the usefulness, robustness and applicability of the tool. The research concludes that SNAPTA offers a useful alternative that can be used in decision-making to inform strategic planning processes for future urban growth and urban structure framed around the integration of land-use with strong public transport accessibility.
Accounting for viscous fingering in relative permeability estimation of special core analysis measurements
(Heriot-Watt University, 2017-08) Pereira, Bruno Miguel Ferreira; Sohrabi, Professor Mehran
Relative permeability (kr) is a critical input data for any calculation involving multiphase flow in petroleum reservoirs. Normally, kr curves are obtained by performing coreflood experiments as part of SCAL measurements or EOR studies. The results of the experiments are then used to obtain kr values often by either analytical models (e.g. JBN) or history matching techniques. Most of these models are based on the Buckley-Leverett displacement theory and are not applicable to unstable displacements. Therefore, using these models to describe a core flood experiment involving viscous fingering will result in potentially large errors in the estimation of kr curves. This study focused on the estimation of relative permeability curves for unstable experiments, more specifically in unfavourable mobility corefloods with a tendency to develop viscous fingering. Refined 2D coreflood simulations were used to evaluate the effect of viscous fingering in kr estimation methods. The simulations were performed as immiscible corefloods in homogeneous cores using a Black-oil model in a commercial simulator. The first part of this study, describes the methodology used to generate viscous fingering in numerical corefloods. Instability triggering methods were used with high resolution simulation to generate the viscous fingering. This methodology was then used to generate different numerical experiments with viscous fingering formation. In the second part, the currently widely used oil industry approaches for relative permeability estimation (1D history matching and JBN method) were evaluated for cases with unfavourable mobility. The errors were quantified in order to understand the effect of fingering on these methods and the amount of error one can incur when using them for these cases. In the latter part of the thesis, two novel methods are proposed for estimating relative permeabilities for unfavourable mobility coreflood experiments, namely viscous fingering. These methods are based on the proposed model called ‘stable equivalent model’. This model proposes a correction to the velocity of the fluids in a coreflood affected by viscous fingering, allowing to account for viscous fingering in relative permeability estimation. The model is used to modify the JBN method and 1D history matching, allowing these methods to tackle viscous instability. The integrity of these techniques was validated against published experimental data and numerical data.
Accurate estimation of macroscopic flow properties in porous media : from REV to upscaling
(Heriot-Watt University, 2025-01) Yaralidarani, Muhammad; Sohrabi, Professor Mehran; Farzaneh, Doctor Seyed Amir; Aghabozorgi, Doctor Shokoufeh
Representative Elementary Volume (REV) is the smallest volume of a porous media above which further size increases do not yield any changes in the measurements of a specific property. It is well established that the REV can vary across geological scales for different static (e.g., porosity) and flow-based properties (e.g., permeability). Most REV studies available in the literature are focused on static properties at the pore scale. However, in this study, we have focused on determining REV for single-phase flow parameters at the core scale to investigate whether SCAL experiments are performed on a representative volume. Also, the feasibility of using tracer tests for determining core scale REV was investigated since the shape of the effluent tracer tests can be a good qualitative indication of the heterogeneity, and the Peclet number can be a quantitative measure. For this purpose, several heterogeneous reservoir sections were generated, and tracer flood simulations were conducted on sub-samples of various sizes. It was demonstrated that, in general, permeability-based REV based on the common approach in the literature closely match the corresponding REV figures showing the accuracy of the novel tracer-based technique. As part of this study, the numerical dispersion associated with various techniques available for the simulation of tracer flow were also investigated and quantified. After identifying REV and performing SCAL experiments on a representative volume, an upscaling method is needed to use the results in reservoir-scale simulations. In this study, a complete set of two-phase numerical coreflood tests, along with a Gaussian Process Regression algorithm (GPR), was used to obtain a data-driven model. This model relates the measured oil production and pressure drop to the basic fluid and rock properties through dimensionless groups. Using dimensionless groups eliminate the impact of sample size on the results. Therefore, a new oil production and pressure drop curve can be calculated using the data-driven model for any larger or smaller sample. The obtained curves can be history matched to find the relative permeability at a larger scale. Next, the proposed upscaling method is extended to three-phase flow by introducing relevant dimensionless groups. The three-phase upscaling methodology is validated against large-scale numerical tests representing different reservoir heterogeneity patterns and fluid properties. The proposed approach demonstrates excellent performance in predicting oil recovery, water production, and pressure drop in three-phase flow systems and also upscaling three-phase relative permeability functions in heterogeneous porous media. In summary, this study contributes to the advancement of REV characterisation and relative permeability upscaling techniques for multi-phase flow in porous media. The developed tracer technique and dimensional analysis approach, coupled with the GPR algorithm, provide an accurate and reliable framework for capturing reservoir heterogeneity and predicting flow behaviour at larger scales. Also, the proposed approach demonstrates superior performance compared to the existing methods. The findings of this study have implications for optimising sampling strategies and enhancing the predictive capabilities of reservoir upscaling models.
Acoustic diffraction by two and three dimensional objects using integral techniques
(Heriot-Watt University, 1990) Nightingale, Trevor R.T.
Acoustical design of water features and their use for road traffic noise masking
(Heriot-Watt University, 2012-10) Al-Musawi, Tahrir Taki Ali; Galbrun, Doctor Laurent
This thesis examines the physical and perceptual properties of water sounds generated by small to medium sized water features, and their use for road traffic noise masking. A wide range of design factors have been tested in the laboratory for waterfalls, cascades, fountains and jets which can typically be found in open spaces such as gardens and parks. A number of field tests were also carried out to illustrate the variability of water sounds. The results obtained indicated that estimations can be made on how design factors affect sound pressure levels, frequency content and psychoacoustic properties. Key design factor findings include the higher sounds pressure levels obtained when distributing the same amount of water over several streams rather than over one uniform stream (+2-3 dB), the increase in the overall sound pressure level at high flow rates with increasing waterfall’s width (+2-3 dB), and the significant increases in sound pressure level with increasing height of falling water (+5-10 dB). Impact materials greatly affected acoustical and psychoacoustical properties, results showing however that changes in sound pressure level and spectra become less and less significant with increasing height and flow rate. Overall, water produced more mid and low frequencies (+5-10 dB compared to hard materials in the range 250 Hz – 2 kHz), whilst hard materials tended to increase the high frequency content of approximately 5 dB. Comparisons with road traffic noise showed that there is a mismatch between the frequency responses of traffic noise and water sounds, with the exception of waterfalls with large flow rates which can generate low frequency levels comparable to traffic noise. Auditory tests were carried out to assess water sound preferences in the presence of road traffic noise. These were undertaken in the context of peacefulness and relaxations within gardens or balconies where motorway noise was audible. Results showed that water sounds should be similar or not less than 3 dB below the road traffic noise level, and that stream sounds tend to be preferred to fountain sounds, which are in turn preferred to waterfall sounds. Analysis made on groups of sounds also indicated that low sharpness and large temporal variations were preferred on average, although no acoustical or psychoacoustical parameter correlated well with the individual sound preferences.
Acoustical designing for speech quality in theatres
(Heriot-Watt University, 1981) Latham, Howard Geoffrey
Activating the role of public participation as a new vision towards urban planning system reform : what can Syria learn from the British experience?
(Heriot-Watt University, 2022-09) Hassan, Alaa; McCarthy, Doctor John P.; Jones, Professor Colin A.; McWilliams, Doctor Christopher
As a cross-national comparative study, this research examines the urban development decision-making process as a form of urban governance, emphasising the progress achieved in public participation within the British and Syrian urban contexts. According to the United Nations Development Programme (UNDP), public participation is one of the key attributes of good governance. Therefore this study addresses public participation as an indicator of good governance; a means to ensure better development, and an end to enhancing the capacity building of the society. There is an abundance of theoretical and practical research addressing the topic of public participation in the urban development decision-making process in the UK, which might provide valuable references and lessons for developing countries to benefit from. Since 2011, Syria has been in turmoil and instability due to the ongoing war in the country, resulting in drastic social, economic, and political changes. Before the war and during the first decade of the 21st century, Syria sought to make some social and economic changes under the influence and help of the UNDP. Those change attempts were noted within the 10th Five Year Plan (FYP), where the concepts of ‘civil society’, ‘participation’, and ‘governance’ were introduced. Those changes have affected the urban planning context within the country, where a new approach to decision-making within the land-use planning system was introduced. However, the efficiency of the new approach to achieving better outcomes for development plans was still questionable. This research aims to critically review, evaluate and compare the progress achieved in the field of public participation in the urban development decision-making process (evolution, achievements, and problems) in the British and Syrian contexts by following a cross-national approach. It reviews the evolution of urban planning theories and public participation approaches and their practices. Based on the findings, an analytical framework is adopted to examine and evaluate the level of public participation within the decision-making process, both theoretically and in practice. The research is based on a case study approach. A mixed-method of data collection and analysis is applied in both countries through literature, policy and regulations reviews, and fieldwork in the selected study cases: Edinburgh, Scotland, UK, and Latakia, Syria. By studying and analysing the possibilities for broader public participation and more effective engagement of members of civil society in the urban development decision-making process, this research attempts to promote potential sustainable outcomes of public participation within their related political, economic, and social contexts. This research found some theoretical similarities between the UK-Scotland and Syria when addressing classic democracy (structure of the state, administrative and geographical division, the structure of state institutions, and the laws and regulations governing). However, the empirical research found that the fundamental differences lie in the practical implementation of the concept of democracy on the ground. Empirical research shows that public participation in the Syrian urban development decision making process is primitive and limited to informing only. Even the methods used to inform the public are ineffective enough and do not achieve the required propagation. Whereas in the case of UK-Scotland, public participation is more developed, and the public is engaged and consulted during the formulation of the decisions. Despite the difference in the level of democracy, the research indicates that Syria could benefit from the British experience. However, achieving this is a political matter that needs a political and societal will that involves restructuring the main forces of society (the state, the market, and the society). Based on the research findings, a series of recommendations have been developed to improve the practice of public participation in the urban development decision-making process and achieve reformatory changes to urban governance in Syria,
Adaptation of housing design to culture change in Syria : concepts and practices in the city of Lattakia
(Heriot-Watt University, 2015-05) Ismail, Reem Hekmat; Jenkins, Professor Paul; Smith, Doctor Harry
Rapid cultural change in contemporary life is affecting housing use and design in Syria, with these becoming more ‘out of line’. This study investigates the nature of cultural change and its impact on housing use in general as a way to explore to what extent it is affecting the appropriateness of housing design in Syria. The study is theoretically based on a social constructionist approach due to the complexity and multidimensionality of the study, especially in understanding how people interpret their housing use and cultural identity. The academic literature review focuses on the links between culture and housing design and reviews the changing nature of these in Syria in the face of modernization, westernization and globalization. Based on a case study approach, the research focuses on one of the cities in Syria most affected by such changes (the coastal tourist city of Lattakia). The research investigates the contextual nature of cultural issues in relation to built environment in the city, drawing on qualitative research methods at both macro and micro levels considering the holistic yet individual implications of the subject of study. Empirical investigations were conducted with appropriate samples of representative households in two formal ‘generically designed’ housing areas - i.e. those not designed for a specific client and not self-designed/built, but designed by either government or private sector architects for a general population. The first housing area was developed by the state with subsidised housing (Youth Housing), which represents a lower middle class group. The second area was the university area (Tishreen University Area), which represents a middle class group with houses designed speculatively by the private sector. In these two areas, research methods included: 39 household interviews using face-to-face questionnaires, photographic documentation, analysis of documented licensed housing design plans, and direct observation. Semi-structured interviews with 11 actors involved in generic housing design (academic architects, professional architects and developers) were also conducted. Two key housing use/design issues were chosen to be investigated as key cultural indicators in housing and also very changeable in the pre-war Syrian context: concepts and practices of privacy in the home (family privacy, intra-family privacy, and women’s privacy) and trends in food preparation and consumption. The study provides detailed social and cultural information on actual house use and residents’ aspirations on a number of implications arising from these factors, as yet unavailable for Syria. One outcome of this research is to recommend design approaches more attuned to current cultural change through a deeper understanding of inhabitants’ actual social patterns and needs - through e.g. guidelines for bigger kitchens with dining space, which reflects the change in food preparation and consumption, increasing the number of bedrooms to provide more intra-family privacy, and providing study/work space in the dwellings.
Adaptive algorithms for history matching and uncertainty quantification
(2014-06) Abdollahzadeh, Asaad; Christie, Professor Mike; Corne, Professor David
Numerical reservoir simulation models are the basis for many decisions in regard to predicting, optimising, and improving production performance of oil and gas reservoirs. History matching is required to calibrate models to the dynamic behaviour of the reservoir, due to the existence of uncertainty in model parameters. Finally a set of history matched models are used for reservoir performance prediction and economic and risk assessment of different development scenarios. Various algorithms are employed to search and sample parameter space in history matching and uncertainty quantification problems. The algorithm choice and implementation, as done through a number of control parameters, have a significant impact on effectiveness and efficiency of the algorithm and thus, the quality of results and the speed of the process. This thesis is concerned with investigation, development, and implementation of improved and adaptive algorithms for reservoir history matching and uncertainty quantification problems. A set of evolutionary algorithms are considered and applied to history matching. The shared characteristic of applied algorithms is adaptation by balancing exploration and exploitation of the search space, which can lead to improved convergence and diversity. This includes the use of estimation of distribution algorithms, which implicitly adapt their search mechanism to the characteristics of the problem. Hybridising them with genetic algorithms, multiobjective sorting algorithms, and real-coded, multi-model and multivariate Gaussian-based models can help these algorithms to adapt even more and improve their performance. Finally diversity measures are used to develop an explicit, adaptive algorithm and control the algorithm’s performance, based on the structure of the problem. Uncertainty quantification in a Bayesian framework can be carried out by resampling of the search space using Markov chain Monte-Carlo sampling algorithms. Common critiques of these are low efficiency and their need for control parameter tuning. A Metropolis-Hastings sampling algorithm with an adaptive multivariate Gaussian proposal distribution and a K-nearest neighbour approximation has been developed and applied.
Adequate model complexity and data resolution for effective constraint of simulation models by 4D seismic data
(Heriot-Watt University, 2014-10) Sagitov, Ildar; Stephen, Doctor Karl
4D seismic data bears valuable spatial information about production-related changes in the reservoir. It is a challenging task though to make simulation models honour it. Strict spatial tie of seismic data requires adequate model complexity in order to assimilate details of seismic signature. On the other hand, not all the details in the seismic signal are critical or even relevant to the flow characteristics of the simulation model so that fitting them may compromise the predictive capability of models. So, how complex should be a model to take advantage of information from seismic data and what details should be matched? This work aims to show how choices of parameterisation affect the efficiency of assimilating spatial information from the seismic data. Also, the level of details at which the seismic signal carries useful information for the simulation model is demonstrated in light of the limited detectability of events on the seismic map and modelling errors. The problem of the optimal model complexity is investigated in the context of choosing model parameterisation which allows effective assimilation of spatial information in the seismic map. In this study, a model parameterisation scheme based on deterministic objects derived from seismic interpretation creates bias for model predictions which results in poor fit of historic data. The key to rectifying the bias was found to be increasing the flexibility of parameterisation by either increasing the number of parameters or using a scheme that does not impose prior information incompatible with data such as pilot points in this case. Using the history matching experiments with a combined dataset of production and seismic data, a level of match of the seismic maps is identified which results in an optimal constraint of the simulation models. Better constrained models were identified by quality of their forecasts and closeness of the pressure and saturation state to the truth case. The results indicate that a significant amount of details in the seismic maps is not contributing to the constructive constraint by the seismic data which is caused by two factors. First is that smaller details are a specific response of the system-source of observed data, and as such are not relevant to flow characteristics of the model, and second is that the resolution of the seismic map itself is limited by the seismic bandwidth and noise. The results suggest that the notion of a good match for 4D seismic maps commonly equated to the visually close match is not universally applicable.
Advanced finite element modelling of coupled train-track systems : a geotechnical perspective
(Heriot-Watt University, 2008) Banimahd, Meysam
Abstract unavailable please refer to PDF
Advancing knowledge on fugitive gas migration from integrity compromised energy wells
(Heriot-Watt University, 2023-05) Gonzalez, Paula Sofia; Cahill, Doctor Aaron Graham; Busch, Professor Andreas
Decommissioned oil and gas wells can suffer integrity failure and release fugitive gases into the environment. This typically occurs unnoticed since post-abandonment monitoring is uncommon. To reach NetZero, methane emissions from fugitive sources such as decommissioned wells, must be mitigated increasing the need for research on this emerging issue. This research aimed to advance knowledge on this topic through three main thrusts. First, by evaluating the integrity of decommissioned wells in the field, finding no signs of integrity failure and highlighting a need for standardised assessment methods. Next, by identifying sedimentary rock properties controlling fugitive gas migration in the shallow subsurface of an area of extensive hydrocarbon development, finding flow will occur through units with low total displacement pressure, or through preferential pathways. Finally, by evaluating data from an airborne methane survey to better understand the incidence rate of well integrity failure and identify well attributes related to its occurrence, finding a 5% failure rate and that well operator, well type, abandonment years, completion type, surface casing vent flow and remedial treatments reported may be linked to integrity failure. Overall, this study will aid in developing effective fugitive gas monitoring and detection strategies, establishing emission targets and identifying parameters involved in development of well integrity failure.
Aeolian architecture and its potential impact on reservoir performance Vol. 1-2
(Heriot-Watt University, 2000) Hern, Caroline
The alignment of strategic objectives within the context of Temporary Multi-Organisations
(Heriot-Watt University, 2017-03) Haniff, Amos Peter; Ogunlana, Professor Stephen; Bowles, Doctor Graeme; Sanders, Doctor John
Current research investigating the alignment of projects with organisational strategy has predominantly focused on formation and implementation of strategic objectives within the boundary of a single, permanent organisation. Within the construction industry, the temporary organisation, created by the client organisation to deliver the project, is formed from multiple organisations that are brought together, under contractual conditions, to engage in a single endeavour. This creates a situation whereby multiple strategic objectives, and hence, multiple perceptions of project success, are pursued at anyone time. The research, forming this thesis, investigates how the varied organisations that comprise a Temporary Multi-Organisation (TMO) seek to align multiple strategic objectives within the context of a single construction project, and realise project success. In achieving this aim, the study exposes a number of ambiguities and difficulties organisations face when seeking to realise strategic objectives through a TMO. Four cases of recently complete construction projects within the public sector were selected for empirical study. Qualitative data collected from interviews with actors across organisations participating in each TMO, was supported by secondary data comprising of project documentation from each case. The study finds that the strategy of the TMO, which evolves to realise project success, is guided by the varied strategic objectives of organisations participating in the project, and is influenced by the environmental conditions, procurement strategies, client complexity and leadership style of the client project manager, which together, influence the strategic behaviour of the TMO. This research contributes to theories of strategic fit and the theory of temporary organisations through a model of strategic alignment within the context of a TMO that explains the complex interactions, which occur when multiple organisations engage within a single construction project. The research also contributes to the understanding of project success through a model of identifying the varied and competing success criteria within a TMO. Finally, the research contributes to leadership theory, through analysis of leadership styles within the context of a TMO.
Analysis and design of linear-to-circular polarising reflector antennas exploiting periodic metallodielectric arrays
(Heriot-Watt University, 2018-04) Mercader Pellicer, Salvador; Medero, Doctor Gabriela M.; Goussetis, Professor George
This thesis presents an eﬃcient way to analyse and design linear-to-circular polarising reﬂector antennas comprising doubly periodic metallodielectric arrays. These type of structures, used in conjunction with subreﬂectors, has risen as a promising solution to reduce the number of reﬂectors in multi-beam antennas in single-feed-per beam architectures while providing circular polarisation for the downlink/uplink. The ﬁrst part of the thesis is concerned with the analysis of single reﬂector antennas, focusing on their depolarisation properties. MATLAB® codes are developed to obtain the far-ﬁeld from the reﬂector and are successfully compared against the preferred tool in the market for the analysis and design of reﬂector antennas, i.e.,TICRA’s GRASP. This analysis tool is used in conjunction with a Floquet analysis of periodic structures to obtain the far-ﬁeld from doubly periodic metallodielectric arrays. An efﬁcient way to extract the fundamental modes from the near-ﬁeld of the feed is introduced for cases where the the reﬂector is placed at the near-ﬁeld of the feed. A design procedure to reduce the cross-polarisation of the polarising reﬂector far-ﬁeld is included. This procedure is based on physical insight rather than brute-force optimisation, leading to computational eﬃciencies. Design examples are shown are compared against the original uniform unit-cell array design. Improvements up to 16 dB in the cross-polarisation levels across a wide bandwidth are achieved. The procedure is validated experimentally. The design procedure is also applied to a multi-beam case where three ideal sources are used to feed the reﬂector. Compared with the uniform unit-cell array, improvements up to 10 dB are obtained in the cross-polarisation performance for the whole bandwidth and the three feeds at the same time.
Analysis and modelling of in situ geochemical reactions in oil fields based on produced Brine chemistry data.
(Heriot-Watt University, 2010-10) Ishkov, Oleg Yuryevich
Management of mineral scale precipitation is one of the major challenges faced by the oil industry. Total costs of scale prevention can exceed £1 million for a field or even sometimes for a single well. Identification of the injection water fraction in the produced brine stream is of importance to production chemists involved in mineral scale prevention. This data is required to determine the onset and the severity of barium sulphate precipitation, one of the most challenging flow assurance issues in the oilfield due to the very low solubility of the mineral. This body of work develops a solution to the problem of how to determine the injection water (IW) fraction in the produced brine. A robust and accurate method for calculating IW fraction in produced water samples is presented. The method has been named the “Reacting Ions” method. The Reacting Ions method is based on interactions between ions during reactions, by correctly taking account of ion losses that will occur due to precipitation. The proposed new method allows injection water fraction to be calculated from concentrations of the ions involved in reactions, which has never been done before. In addition, the new method incorporates as a limiting case the Ion Track method - the most widespread method currently used in the industry. The Reacting Ions method removes the limitation that only conservative ions can be used to track injection brine in produced water. This Reacting Ions method is applied to a synthetic produced water case, generated using a reservoir simulator, where the “correct” IW fraction is known, and a very good match is achieved, even when significant noise is applied to the synthetic data. An additional outcome of the synthetic case tests is that conventional use of sulphate in the Ion Track method leads to a late detection of injection water breakthrough, while the Reacting Ions method based on barium and sulphate is significantly more accurate. Delayed detection of injection water breakthrough can lead to the onset of scaling before preventative measures have been taken. The Reacting Ions method was applied in the analysis of produced brines for more than 100 wells in several regions of the North Sea. Results of the study presented here show that the method is generally more effective in detecting IW fractions than conventional ion tracking techniques, especially at low IW fractions soon after breakthrough occurs. Using barium and sulphate, the new Reacting Ions method benefits from near zero end-point concentrations of iii these two ions that is typical for North Sea brines, and is consequence of the low solubility of barite. The more accurate identification of IW fraction has led to the development of three applications that use the Reacting Ions method. In the first, the relative ion deviations are used to identify whether an ion is conservative, precipitating or part of a dissolution reaction. This information can be applied by production chemists to predict possible types of mineral scale occurring. The second application assists in detecting which formation or formations the well is producing from, which gives incremental information about the reservoir itself. In the third, a method to analyse squeeze treatment response is proposed. The impact of scale inhibitor placement on the ion concentrations is evaluated, and thus a judgement can be made regarding the overall effect of the squeeze treatment in stopping the identified scale reactions from happening. All three new applications were successfully applied to field data.