Energy, Geoscience, Infrastructure and Society
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Item Imaging solutions for 4D quantitative interpretation(Heriot-Watt University, 2022-12) Izadian, Saeed; MacBeth, Professor Colin; Amini, Doctor HamedDuring the production of a geomechanically active reservoir, massive pressure depletion happens giving rise to geomechanical changes which can lead to significant time-lapse signals across the reservoir and its surrounding. Therefore, geomechanical characterisation of the reservoir and monitoring are very important for this type of reservoir. In this thesis, I use pre-stack time-lapse time-shifts observed between 4D seismic surveys for the geomechanical characterisation of the Ekofisk field which is a geomechanically active field in the North Sea. This thesis consists of three parts. Before using pre-stack time-shifts, post-stack time shifts can be a valuable guide toward the geomechanical activities of the reservoir. In the first part, I estimate the post-stack time-shifts using various methods. Then, I evaluate the advantages and disadvantages of each method in terms of their performance in revealing the local time-lapse signals such as time-strains. I have found that all the time-shift methods can successfully measure time-shifts. Among them, NLI is the most outstanding method as it gives smooth time-shifts with relatively good accuracy and the time-strains derived from there are more stable and interpretable. In the second part, I use the reflectivity and velocity models of the Ekofisk field and perform a finite-difference simulation to generate synthetic seismic data, followed by imaging the generated data. Migrating baseline and monitor datasets with baseline velocity model caused considerable mispositioning in the overburden resulting in false amplitude-differences in the overburden. The analysis of the images shows that it is not simply a matter of mispositioning that contaminates the seismic images. A more serious problem caused by migration with an erroneous velocity model is the defocusing of amplitudes. This problem cannot be solved by warping and requires a more sophisticated remedy to correct the monitor’s migration velocity model. In the third part, which is the major development of this thesis I measure the pre-stack time-shifts and design a tomographic approach to utilise them for estimating the time lapse changes. First, I show how to measure the pre-stack time-shifts and discuss the practical aspects of the process. Second, I design a ray-based tomography customised for 4D application in order to utilise the pre-stack time-shifts and invert for velocity changes that cause the time-shifts. Finally, I extend the tomography method into an anisotropic inversion where both the time-lapse velocity changes and the ratio of lateral-to-vertical strains are inverted in a two-step inversion process. The two products of the inversion can be used extensively in the geomechanical model calibration of the reservoirs. Overall, my PhD research has successfully measured the time-lapse velocity changes and the ratio of lateral-to-vertical strains. The anisotropic time-lapse tomography is a new paradigm in the pre-stack time-lapse seismic analysis and will be an integrated part of the geomechanical characterisation of the reservoirs.Item Smart construction and industry 4.0 challenges and opportunities : a strategic and operational framework to unlock digital transformation(Heriot-Watt University, 2024-11) El-Hawary, Maged Sayed Amin Naguib; Nielsen, Doctor YaseminThe construction industry is always fragmented, labour-intensive, and has slow technology adoption and low-profit margins. Nevertheless, with the development of different global sectors, improvement becomes mandated, especially given the complexity, tight budgets, and squeezed time frames. Rethinking the delivery of construction projects became vital to planning, operating, delivering, and measuring success as the world witnessed a historically unprecedented industrial disruption. This revolution entails transforming humankind. Unlike any predecessor with a linear pace of expansion, Industry 4.0 is spreading exponentially, renovating all traditional strategies and aiming to transform business models across countries, governments, companies, industries, and societies. Like other industries, the construction industry has struggled to take advantage of technology significantly. A fourth industrial revolution and its subsequent "Industry 4.0 and construction 4.0" terminology are invading advanced industries, calling for fully integrated digitalised value chains across ecosystems. The Internet of Things (IoT), digitalisation and offsite construction became the essence of overcoming industry pitfalls. Construction is moving from a Resource-based industry to a knowledge-based sector, considering the borderless boundaries between different sectors by adapting the cross-industry cooperation concept. The research investigates industry 4.0 opportunities and their potential impact on the construction industry throughout the project life cycles from inception to asset management. It seeks to improve physical site delivery by reviewing related concepts, technologies, and supply chains. Emerging technology priority areas are identified, implementation mandates are explored, and challenges and enablers are distinguished. A framework and Roadmap for incorporating industry 4.0 concepts and technologies are proposed. A triangulation approach was adopted throughout the research to integrate results from a literature review and other field works. Focus group workshops helped to understand industry issues and were a key input towards questionnaire design. Survey questionnaires highlighted industry drawbacks and expected improvement of emerging technology implementation, concentrating on linking potential technology and industry inefficient practices. Interviews with industry experts were crucial in associating the findings with corporate strategic objectives and initiating the roadmap. The fieldwork was conducted to satisfy pre-defined research objectives and Initiate/validate the proposed framework for successful implementation at both operational and strategic levels. The primary outcome of the research is a framework and roadmap for digital transformation initiatives with a concentration on the main contractors operating in the GCC area to empower the utilisation of industry 4.0 technologies; both were developed from the field/desk works and validated with different stakeholders operating in the construction industry as the pandemic situation of COVID-19 enforced the need for more technology utilisation and enhanced industry professional awareness and willingness to adapt and change the conventional methods of entire project delivery.Item Enhancing energy demand forecasting and data imputation using deep learning : an integrated approach(Heriot-Watt University, 2024-11) Lotfipoor, Ashkan; Patidar, Doctor Sandhya; Jenkins, Professor David P.This PhD thesis introduces an integrated approach that leverages deep learning techniques to advance household electricity demand forecasting and data imputation within the UK energy sector. The research focuses on creating a novel system incorporating state-of-the-art machine learning solutions for electricity demand processing and prediction. The study involves data collection from appropriate electricity demand datasets, conducting comprehensive exploratory data analysis to uncover underlying patterns. A framework is established to process these datasets, encompassing data imputation, outlier handling, transformations, and feature scaling. A novel missing value imputation model is developed, employing a Transformer neural network and a K-means clustering algorithm to address missing data effectively. Subsequently, a forecasting framework for short-term residential load prediction is presented. This modelling framework integrates a Bayesian optimisation strategy, feature decomposition techniques, feature engineering, and percentile-based bias correction algorithms with a CNN-LSTM network to enhance prediction accuracy. The research contributes significantly to the field of household electricity demand forecasting and data imputation by offering a scalable and transferable framework. The application of these methodologies yields valuable insights, not only for the UK energy sector but also for broader applications, enabling precise predictions and efficient demand data processing. The findings promote energy efficiency and sustainable energy management practices.Item Applying ANN technology to determine acceptable control parameters for the National Library of Scotland’s collections to inform energy efficiency improvements in the UK heritage sector(Heriot-Watt University, 2024-12) Han, Bo; Wang, Doctor Fan; Taylor, Professor NickThe National Library of Scotland (NLS) uses purpose-built storage enclosures to protect their heritage collections. These enclosures can moderate micro-environmental temperature and humidity fluctuations inside. This study aims to determine an acceptable macro-environment in storage room to inform energy efficiency improvements based on a relaxing macro-environmental control. There are four objectives: 1) to assess the feasibility of using the enclosure’s buffering capacity and to obtain its hygrothermal properties; 2) to determine an acceptable macro-environment; 3) to achieve real-time micro-environment predictions; and 4) to assess potential energy savings from the relaxed control strategy. Correspondingly, the methodology comprises four parts: 1) using laboratory measures to quantify the buffering capacity of an enclosure and associated hygrothermal properties; 2) using a heat, air, and moisture (HAM) transfer model to simulate the hygrothermal interaction between macro- and micro-environments, and using a trial-and-error method with this model simulation to determine the acceptable macro-environment; 3) training a long short-term memory neural network; and 4) using a transform function to create the energy consumption model. The results show that 1) The enclosure’s buffering capacity is feasible to moderate the short-term micro-environmental temperature and RH fluctuations. 2) The acceptable macro-environment was determined to be 33%~65% RH and 15-25 °C control bands with ±16% RH and 5 °C 24 h fluctuations while there is no any detrimental effect on collections. 3) The trained Long Short-term Memory (LSTM) neural network can is robust for real-time prediction of micro-environment. 4) Implementing the relaxed control strategy presents a promising way to achieve the NLS's targeted annual reduction rate of 7.6% over the next decade. In conclusion, this study confirms that relaxed macro-environmental controls, enabled by the enclosure’s buffering capacity, ensure collection safety while achieving significant energy savings. Additionally, this control strategy advances the NLS’s building management toward smarter, energy-efficient control and offers scalable solutions for other heritage institutions.Item The use of offset-dependent time-shifts to characterize dynamic overburden effects in 4D seismic data(Heriot-Watt University, 2023-04) Dvorak, Ilona; MacBeth, Professor ColinTime-lapse seismic surveying is used for the monitoring and management of hydrocarbon fields in order to evaluate production-related subsurface changes that occur in the reservoir system. The time-lapse seismic method conventionally analyses 4D attributes of the reservoir which are generated from stacked versions of the base and monitor datasets which, in turn, are imaged using a common velocity model. A drawback of this approach is that changes that are observed in the time-lapse data that occur in the overburden above the reservoir unit may not be corrected for in the seismic workflow. This lack of update degrades the quality and reliability of the resultant reservoir time-lapse analysis. This research project investigates the effects of dynamic changes in the overburden, i.e., variations in conditions in the medium above the producing reservoir, which occur between the acquisition of the baseline and monitoring survey datasets. The objective of this research is to evaluate the dynamic overburden effects on the monitoring programme of the target time-lapse reservoir, to interpret dynamic overburden effects through the use of 4D time-shift attributes and design methodologies to compensate for dynamic overburden variations. The focus of this research is the Shearwater field, a high-pressure, high-temperature central North Sea field, which exhibits a common dynamic overburden system of extensional stress-arching as a reaction to compaction in the Jurassic reservoir unit. A synthetic modelling study of a variety of dynamic overburden features shows variability in the magnitude of time-shift responses as a function of the source-receiver offset at common midpoint locations beneath the overburden anomalies. These pre-stack, 4D, time-shift variations are found to be sensitive to the geometry and distribution of the 4D overburden anomalies, according to the relative exposure of the seismic ray-paths that transect the 4D effect. Dynamic overburden effects in the Shearwater field are interpreted via the derivation of pre-stack time attributes of time-shift intercept and time-shift gradient, which are generated via least-squares fitting of time shifts as a function of offset derived from the base and monitor datasets. There is agreement between the pre-stack time-shift attributes and the established overburden extension system. A weak negative gradient of time-shift is noted at the Top Fulmar reservoir. These attributes are also found to agree with those from an analogue at the South Arne field, in which a decrease in time-shift is reported from near to far offsets. The interpretation of the pre-stack, time-shift attributes for the Shearwater field indicates the value that can be achieved through analysis of pre-stack 4D data, as its use can enable the characterisation of 4D anisotropy velocity effects and the derivation of geomechanical attributes such as the stress path parameter. Two techniques are developed to derive the perturbation velocity from the pre-stack time-shift. The perturbation velocity is defined as the change in seismic velocity between the base and monitor surveys. Derivation of the perturbation velocity offers the opportunity to compensate for dynamic overburden effects that are traditionally ignored in the seismic workflow, via monitor survey imaging. The first method utilises bi-linear stacking in the offset domain and relocation of the 4D effect to its implied subsurface location, based on a geometrical relationship. The application of this method to the Shearwater dataset enables the derivation of a model that shows alignment to the overburden extensional slow-down and local variations that coincide with fracture closures in the Hod formation. The second method involves linear least-squares tomography of pre-stack time-shifts. Application of this technique to Shearwater leads to the derivation of a model that is aligned with a vertical strain field generated from a Geertsma model produced from post-stack time-shift data. This project demonstrates the value of pre-stack inversion in 4D seismic methods and its potential to improve accuracy in 4D analysis and to deliver information from post-stack analysis that goes beyond conventionally established workflows.Item Exploring the impact of sewer-derived airflows on the air-pressure dynamics within building drainage systems(Heriot-Watt University, 2024-10) Sharif, Khanda S.; Gormley, Professor MichaelThe performance of a building drainage system (BDS) relies on complex internal airflow and pressure dynamics, governed primarily by the unsteady wastewater flows from randomly discharging appliances such as WCs, sinks and baths. Designers attempt to optimise the safety of the system by including pressure equalisation strategies in the form of ventilation pipes and more active devices such as pressure attenuators and air admittance valves. Failures within these systems can compromise water trap seals, allowing hazardous sewer gases to enter buildings. While these measures can equalise the air pressure within the above ground drainage system, air coming from the sewer can have an effect on the performance also. Traditionally, above and below ground drainage systems are designed in isolation and there is no recognition of the influence of one on the other. This thesis documents the development of a novel model to represent the impact of sewer air on the performance characteristics of a BDS, leading to the development of new conceptual diagrams describing the interaction, that illustrate the correlation between newly introduced terms, such as; modified entrained air and modified air pressures, when the system is exposed to both BDS operation and sewer air. Laboratory experiments were conducted using a full-scale drainage test rig representing both low rise (3 storey) and high rise (34 storey) buildings that together provide empirical insights scalable to real-world applications. This approach bridges the gap between laboratory experiments and real-world dynamics, thereby enhancing the reliability and applicability of the research findings. The research confirmed that the airflow and air pressure regime within the vertical BDS stack is modified by and influenced by the connection to the main sewer in a manner consistent with an interaction analogous to a fan and system loss curve, requiring the solution of simultaneous equations describing both. The findings of this study confirm a direct correlation between pressure fluctuations and building height when exposed to sewer air.Item Immiscible fingering in porous media under different wetting conditions and its role in polymer flooding(Heriot-Watt University, 2024-11) Beteta, Alan; Sorbie, Professor Kenneth Stuart; Mackay, Professor Eric JamesImmiscible viscous fingering occurs when a low viscosity fluid immiscibly displaces a high viscosity fluid. In the field of geoenergy, this is typically a major problem whether in gas storage or in oil recovery. When water is injected into the reservoir to aid recovery, it can finger through a viscous oil, leaving large volumes bypassed and giving early water breakthrough – neither of which is ideal from an economic or carbon footprint viewpoint. Three major questions present themselves with regard to viscous fingering in such systems: how can fingering be modelled correctly?; how can fingering be evaluated in the laboratory?; and how can it be remedied? These are the 3 main areas of research that will be addressed in this thesis. A novel simulation methodology is used to directly model viscous fingers using standard, commercial numerical simulators. In this work, this approach is validated against literature experiments at a range of unstable viscosity ratios (μo/μw ~400 to 7,000). It is then applied to model conventional core flood experiments, conducted as part of this thesis, where μo/μw = 100. The simulation method is then used to upscale the core flood results using scaling theory to a series of conceptual and sector models of the Captain reservoir, which is currently undergoing polymer flooding in the North Sea. The same numerical method is used to demonstrate how laboratory scale unstable displacement experiments are sensitive to the suppression of viscous fingering by capillary dispersion. This is then shown to occur even under extremely weak wetting conditions. Using scaling theory, it is then shown how fingering “remerges” as the system size is increased towards the field scale. These observations are then further supported by carrying out laboratory 2D slab flood experiments under different wetting conditions for an unstable immiscible displacement with viscosity ratio μo/μw = 100. The systems studied include a weakly water-wet case which shows an apparently stable front, while the equivalent weakly oil-wet system is highly fingered. By applying scaling theory, it is demonstrated that capillary forces must be made negligible at the laboratory scale in order to maintain the same viscous-capillary force balance which applies at the field scale system. Finally, the well-established enhanced oil recovery technique of polymer flooding is re-evaluated in the context of these findings. It is demonstrated both by simulation and experiment that the principal increased recovery mechanism of the polymer is through viscous crossflow. This mechanism is shown to be responsible for the large and very rapid response in oil recovery on polymer injection – even in highly viscous systems (>2,000 mPa.s) - as bypassed oil crossflows into established water channels (fingers). This mechanism is evident in the laboratory when viscous fingers are allowed to form (viscous-dominated) and supports the conjecture that both polymer flooding and water flooding are best examined without the stabilising effect of capillarity. In addition, the findings of this thesis cast doubt on the conventional methods of “measuring” relative permeability in the laboratory for application in adverse viscosity ratio immiscible displacements in the field.Item Data-driven discovery of novel lasso peptides with pharmaceutical applications(Heriot-Watt University, 2024-10) Giard, Josephine Marie; Kerr, Doctor Leena; Smith, Professor David; Alexander, Doctor RossAntimicrobial resistance is a major global health threat and to combat it, there is a need to discover novel antimicrobials. A promising target for novel drug discovery are lasso peptides, a class of secondary metabolites with desirable characteristics and sought-after bioactivities. Here, novel lasso peptides with antimicrobial activity and Streptomyces origin were sought by using DNA sequencing data to guide experimental procedures. Initially, it was tested if a high abundance of Actinobacteria and Streptomyces can be used as an indicator for environments with high potential for secondary metabolism. Subsequently, metagenomic and bacterial whole genome sequencing data were assessed for the presence of lasso peptide gene clusters which led to the prediction of 177 potential lasso peptide gene clusters. Predicted lasso peptide gene clusters were further analysed for antimicrobial potential, novelty, sequence diversity, and Actinobacterial origin, and two lasso peptide gene clusters were chosen as cloning targets for further experiments. One target lasso peptide gene cluster was amplified from eDNA extracted from a volcanic cave biofilm and subsequently expressed by cell-free biosynthesis and maltose-binding protein cloning. The antimicrobial potential of the expressed novel lasso peptide was tested by screening for inhibitory activity against a selection of (multidrug resistant) ESKAPE pathogens. The results indicated an effect on the growth of Staphylococcus aureus. In addition to the expression of individual lasso peptide gene clusters, Streptomyces strains were isolated from environments suggested to be rich in lasso peptides. A selection of isolates was PCR-screened for lasso peptide genes. Positive PCR results could be confirmed by Sanger but not by whole genome sequencing.Item Site optimisation for native oyster (Ostrea edulis) reintroduction and its realistic application to modern day site suitability analyses(Heriot-Watt University, 2024-10) Cooper-Young, Emmy Louise McLeod; Sanderson, Professor William; McWhinnie, Doctor Lauren; Hartl, Doctor MarkOyster populations have been globally depleted by 85% and historical Ostrea edulis beds may no longer be suitable due to anthropogenic and natural changes. Robust site suitability assessment must occur in prospective restoration sites to determine if restoration is feasible in the current environment. Studies on the environmental preferences of the species are mostly based on lab studies and expert observation and opinion. The relationship between oyster density and environmental conditions in the last natural oyster fishery in Loch Ryan, Scotland, were tested in a unique field study. The percentage of hard substrate and presence of gravel significantly influenced oyster density across the loch. The optimum environmental conditions determined from Loch Ryan informed a MCDA-GIS based site suitability model in the Firth of Forth, Scotland. The most suitable sites for O. edulis restoration in the Forth were identified around Inchkeith, Leven/Kirkcaldy and North Berwick with varying confidence. The outcome of the suitability analyses varied based on the importance applied to sub-models in response to different restoration scenarios. Application of this type of modelling in similar environments must carefully assess and weigh the parameters according to the species needs within the specific environment and its associated pressures.Item Solubility of light ends in heavy condensates(Heriot-Watt University, 2024-10) Goni, Mustapha Umar; Chapoy, Professor Antonin; Burgass, Doctor Rhoderick William; Ahmadi, Doctor PezhmanThe research work aims to improve the prediction of the vapour-liquid distribution of light hydrocarbons in heavy raw condensate production streams by gathering and evaluating the available experimental data. The principal motivation of this research initiative was to generate a comprehensive data set to assist in the efficient and economic design and running of condensate stabilization facilities. Vapour liquid equilibrium (VLE) data for binary systems of light hydrocarbons (ethane, propane and n-butane) in heavier hydrocarbons were gathered from the literature. The gathered datasets were evaluated using predictive Peng Robinson (PPR78) and multifluid Helmholtz energy approximation (MFHEA) equations of state. Experiments were conducted to generate VLE data for binary and multicomponent systems of light and heavy gas condensate ends up to 373 K and 10 MPa using an isochoric setup. This effort yielded entirely new datasets for binary systems of ethane and propane in n-decane, n-undecane, n-dodecane and n-tridecane respectively. Six multicomponent systems composed of varying amounts of n-alkane components were synthesised as part of this study and their VLE properties (bubble point) determined. The new binary and multicomponent systems VLE data generated were correlated/predicted using the PPR78 EoS, MFHEA EoS and PC SAFT EoS with good agreement observed between the experimental data and model correlations/predictions. The gathered VLE data were used to fit the βT_ij and γT_ij parameters of the MFHEA EoS while keeping the βv_ij and γv_ij BIPs equal to unity. This formed the basis for the development of a model for predicting the βT_ij and γT_ij BIPs for the MFHEA EoS using group contribution (GC) method. The model covers systems composed of n – alkanes with future studies proposed to extend its application to components such as cycloalkanes, aromatics and non-hydrocarbon components such as CO2, H2S and N2.The GC model was validated using binary and multicomponent systems with good agreement between the experimental data and model predictions.