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Collaborating Authors
University of Nottingham
Machine-Learning-Based Proxy Modelling for Geothermal Field Development Optimisation
Otchere, Daniel Asante (Universiti Teknologi PETRONAS) | Latiff, Abdul Halim Abdul (Universiti Teknologi PETRONAS) | Taki, Mohamed Yassir (BluMarbl, Netherlands) | Dafyak, Longtong Abedenego (University of Nottingham)
Abstract More than 40 billion tonnes of CO2 are released annually, hampering climate change efforts. The goal of current research is to utilise these gases in generating energy. The oil and gas industry faces increasing expectations to clarify the implications of energy transitions for their operations and business models, reduce greenhouse gas emissions, and achieve the Paris Agreement and Glasgow Climate Pact targets. A solution is integrating machine learning and geothermal energy to optimise field development to reduce CO2 emissions while meeting energy demands. The study area is a simulated actual field data, with three existing geothermal doublets and six exploration wells. The development plan aims to satisfy the energy demand for two locations, D1 and D2, for the next 100 years, using geothermal energy and optimising field development plans via machine learning models as surrogate models. A pseudo-geological model was developed using limited field data to identify sweet spots for further drilling. Four separate model cases were simulated using DARTS. The time-energy data from DARTS was then used to train and test several machine learning models to serve as a proxy model to optimise the best strategy to meet the energy demand. The economic model was simulated for 20 years for the selected strategy for field development. Using an injection rate of 500 m3/day per well to validate the ML models, the best-performing model had a mean absolute error within the range of 0.6 to 1.5 MW for all the doublets. Based on the ML results, the computational power and time required for field development plan simulation were dramatically reduced, and several configurations were performed. The optimal strategy for this field comprises 7 geothermal doublets, 3 for D1 and 4 for D2. This strategy uses all available wells to avoid lost investment or excess cost when those wells are needed to complement production when decline sets in after 20 years, allowing a reliable and long-term energy supply. This strategy will achieve a net energy output of 108 MW for D2 and 82 for D1. This strategy uses machine learning energy estimation for the optimum configuration and addresses the issues of excess energy storage, uncertainty in production, and rising energy demand. The economic model was based on a fixed OPEX, an estimated Capex based on field development strategy, and an associated discount rate of 7%. The project resulted in a Levelized Cost of Energy of €11.16/MWH for 20 years whiles reducing annual CO2 emissions by about 367,000 metric tons. This study shows that geothermal energy is a crucial step toward cleaner energy. ML can speed up the energy transition by optimising geothermal field development. This research aims to reduce CO2 emissions while meeting energy needs.
- Europe (1.00)
- North America > United States > New York (0.28)
- North America > United States > Texas (0.28)
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Renewable > Geothermal > Geothermal Resource (0.86)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 050 > Block 34/10 > Gullfaks Field > Statfjord Group (0.99)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 050 > Block 34/10 > Gullfaks Field > Lunde Formation (0.99)
- Europe > Norway > North Sea > Northern North Sea > East Shetland Basin > PL 050 > Block 34/10 > Gullfaks Field > Lista Formation (0.99)
- (4 more...)
Empirical Modelization of Intermittent Gas/Liquid Flow Hydrodynamic Parameters: The Importance of Distinguishing between Plug and Slug Flows
Arabi, Abderraouf (SONATRACH, Direction Centrale Recherche et Développement, and University of Sciences and Technology Houari Boumediene (USTHB)) | Azzi, Abdelwahid (University of Sciences and Technology Houari Boumedien (USTHB)) | Kadi, Rabah (SONATRACH, Direction Centrale Recherche et Développement) | Al-Sarkhi, Abdelsalam (King Fahd University of Petroleum and Minerals) | Hewakandamby, Buddhika (University of Nottingham)
Summary Intermittent flow is one of the most complex flow regimes in horizontal pipes. Various studies have classified this regime as two distinct subregimes: plug and slug flow. This classification has been made based on flow observations. In this work, the behavior of several flow parameters that characterize plug and slug flow are presented. Data from eight published works in the open literature were collected and studied to explain the behavior of both regimes. These data include pressure drop, void fraction, and slug frequency, as well as the lengths of liquid slugs and elongated bubbles for slug and plug regimes. It is observed from the evolution and analysis of these parameters that plug and slug flows have several different distinct features and should be considered as two separate regimes for the empirical modelization of the hydrodynamic parameters. The mixture Froude number, and to a lesser extent the liquid superficial velocity to gas superficial velocity ratio, seem to have significant impacts on the plug-to-slug flow transition. Introduction A variety of fluids (oil, natural gas, water, condensates, and condensed vapor) in the petroleum and gas industry can form two-phase flow.
- Europe (0.93)
- Africa (0.68)
- North America > United States > Texas (0.46)
- North America > Canada > Alberta (0.28)
Experience Using Electrochemical Noise for Testing Green Corrosion Inhibitors
Mills, Douglas J (University of Northampton) | Zatland, Joshua (University of Nottingham) | Everitt, Nicola M (University of Nottingham)
Abstract ‘Green’ corrosion inhibitors derived from plant materials provide environmentally friendly alternatives to conventional corrosion inhibitors. They are also much cheaper if using a biomass waste stream or abundant plant material as the source material. There are many examples in literature of different trials, from henna leaves to celery seeds to banana peel. Although it is known that extracts contain electron-rich polar atoms such as N, O, S and P which make them potentially effective inhibitors, it is difficult to predict on a molecular basis what will work well and what will not, since many interacting factors may be at play in complementary interactions. To assist in predicting the inhibition efficiency of inhibitors under varying conditions and choosing the most effective, what is needed is a short-term test which will obviate the need for tedious weight loss experiments. The Electrochemical Noise Method (ENM) uses the natural fluctuations which arise during electrochemical activity to gain information about the corrosion process. Using ENM is quick and non-intrusive method which makes it ideal for screening. Hence a rig has been designed and manufactured which allows for measurement to be made in stirred as well as static conditions and minimises the occurrence of crevice corrosion at the electrodes. Crevice corrosion is a hazard for ENM electrodes when trying to make a comparison with corrosion inhibition calculated using the standard weight loss measurement after immersion (WLM) method. For these preliminary trials we are exploring corrosion of mild steel in HCl in both stirred and unstirred conditions at room temperature. Results are presented comparing ENM measurements with conventional WLM for both Propargyl Alcohol (a conventional industrial corrosion inhibitor) and broccoli extract. Our results suggest that stirring does not make any difference to the noise measured in ENM. The amount of material lost calculated by ENM and WLM (Rn and weight loss values) can be directly compared and show close comparison. It seems likely that as a way of assessing inhibitors quickly (which is particularly important in the testing of "green" inhibitors) that this ENM approach has a lot to offer.
- Research Report > New Finding (0.54)
- Research Report > Experimental Study (0.34)
- Water & Waste Management > Water Management > Water & Sanitation Products (1.00)
- Materials > Chemicals > Specialty Chemicals (1.00)
- Health & Medicine > Therapeutic Area (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Well Completion > Well Integrity > Subsurface corrosion (tubing, casing, completion equipment, conductor) (1.00)
- Production and Well Operations > Production Chemistry, Metallurgy and Biology > Corrosion inhibition and management (including H2S and CO2) (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Materials and corrosion (1.00)
Relaxation Zone Method in SPH-Based Model Applied to Wave-Structure Interaction
Altomare, Corrado (Ghent University) | Tagliafierro, Bonaventura (University of Salerno) | Suzuki, Tomohiro (Flanders Hydraulics Research) | Dominguez, Jose M. (Vigo University) | Crespo, Alejandro J. C. (Vigo University) | Briganti, Riccardo (University of Nottingham)
ABSTRACT The Relaxation Zone method (RZ) has been implemented in the meshless SPH-based DualSPHysics code. RZ acts as an internal wave maker and allows coupling DualSPHysics with any other model or analytical solution to generate sea waves. In this work, the coupling with the SWASH model is performed to simulate multi-scale and long-duration phenomena in coastal engineering, which represent a challenge for researcher and practitioners. In fact, despite the fact that SPH-based models are getting more and more popular in coastal and civil engineering, they still present a huge computational cost. In the present work, RZ is validated for phenomena of overtopping flow impacts on vertical walls. The results proved that the RZ is efficient and reliable alternative for wave generation in SPH-based models for coastal engineering applications. INTRODUCTION Smoothed Particle Hydrodynamics method (SPH) is a promising meshless technique for modelling fluid flows and fluid-structure interaction (FSI) as it is capable to deal with large deformations, complex geometries, violent free-surface flows inducing large abrupt hydrodynamic loads and highly nonlinear phenomena (Violeau, 2012). In general, SPH methods can be categorized into two groups: weakly compressible and incompressible. The Weakly Compressible SPH (WCSPH) methods solve an appropriate equation of state (Tait's equation) in a fully explicit form. The DualSPHysics model used in the present work is based on WCSPH. The incompressible SPH (ISPH) methods (e.g. Shao & Lo, 2003) solve a Poisson pressure equation (PPE) by applying project-based methods. Latest advancements have been made during the last decade in the context of SPH methods in terms of model stability, accuracy, energy conservation, boundary conditions and improved simulations of multiphase flows and fluid-structure interactions. A comprehensive review of it is presented in Gotoh & Khayyer (2016, 2018). SPH methods have been widely applied to coastal engineering problems, such as wave breaking (e.g. Khayyer et al., 2008), wave overtopping (e.g. Gómez-Gesteira et al., 2005), wave run-up (e.g. Zhang et al., 2018), wave impacts (e.g. Altomare et al., 2015), tsunamilike wave processes (e.g. St-germain et al., 2014), wave energy applications (e.g. Crespo et al., 2017). Notwithstanding, further research is still needed to enhance the reliability of SPH methods and to widen their applicability for coastal engineering problems. Lately Rota Roselli et al. (2018) presented an automatic optimization framework to find the set of SPH parameters in DualSPHysics for an accurate wave propagation modelling. Yet, there are still limitations to be solved, one of which consisting in the unphysical oscillations in the pressure field due to high-frequency acoustic noise. Meringolo et al. (2017) proposed a procedure to filter out this noise, however the work is dedicated to post-processing analysis rather than solve the problem a priori. For WCSPH, besides the most classical diffusion schemes such as artificial viscosity (Monaghan, 1992), the so-called δ-SPH scheme has been proposed (e.g. Molteni & Colagrossi, 2009) to increase accuracy of the pressure field. To improve both accuracy and stability in SPH, particle regularization schemes have been proposed in order to regularize the anisotropic distributions of particles prone to be formed due to Lagrangian characteristics of particle methods (Lind et al., 2012).
- Europe > Belgium (0.29)
- Europe > United Kingdom > England (0.28)
- Information Technology > Artificial Intelligence (0.48)
- Information Technology > Hardware (0.46)
Experimental investigation of gas lift performance in a large diameter pipe
Ibrahim, A. (University of Nottingham) | Hewakandamby, B. (University of Nottingham) | Azzopardi, B. (University of Nottingham)
Abstract An experimental study has been conducted in a co-current 127mm ID facility using air and silicone oil of 5cP viscosity. Results were obtained for passive lifting system, pump-assisted gas lifting and a fixed flow loop in the range of gas superficial velocities (Ugs =0.01 to 1.71m/s) and liquid superficial velocities of (Uls=0.01 to 2.00m/s). Void fraction data was obtained at five axial positions using two twin planes electrical capacitance tomography (ECT) sensors and a (32×32) wire mesh sensor (WMS). The WMS has been used to obtain information about void fraction and bubbles distribution. Three injector geometries have been employed, the effect of injection method on flow development, regime transitions, bubbles sizes and their distribution and the gas structures velocities has been investigated. The flow regimes observed in the test section ranges from dispersed bubbly flow to churn-bubbly regime. Introduction Gas-lifting is achieved by injection of gas to the bottom of the wells to decrease the density of the fluids in the well's column, and accordingly decrease the gravitational pressure gradient without increasing much of the frictional losses. The gas-lift efficiency is dependent on many parameters that include, gas injection rate, type and geometry of the gas injector which affects the bubble size and concentration, and essentially the flow regime. The mechanism by which gas is introduced near the base of the well has been reported to affect the efficiency of gas lift [1]. The injector geometry affects the initial bubble size distribution; introducing smaller bubbles should positively improve the lift efficiency as they have a lower rise velocity and therefore higher void fraction is achieved in the well for the same gas input. Hence, lower mixture density is generated in the well and therefore larger flow of liquid is produced. The effect of the gas injector on the bubbles' distribution extends to influence the lateral distribution of void fraction as smaller bubbles have more even distribution in the cross-section resulting in a higher void fraction and therefore better efficiency. Moreover the injection method have a great influence on the bubble relative velocity, bubbles coalescence and break-up, time/space variation of void fraction and the flow pattern transition which affects the system stability [2]. The majority of the previous investigations on gas lift have been carried out on relatively smaller pipes and for considerably less viscous fluids. This paper will be reporting the experimental campaign conducted in a 127mm (5 inches) internal diameter using 4.83cP silicone oil.
- Research Report > New Finding (0.89)
- Research Report > Experimental Study (0.67)
Obtaining Foundation Rock Mass Properties of the Surqawshan Earth Dam using UDEC
Alshkane, Younis (University of Nottingham) | Marshall, Alec M. (University of Nottingham) | Stace, Rod (University of Nottingham)
Abstract One of the most challenging tasks in rock mechanics is the accurate evaluation of deformability and strength characteristics of jointed rock masses. Attempts to characterise large-scale rock mass properties in the laboratory are seldom undertaken due to the difficulty of obtaining and testing large samples. The in-situ interaction between intact rock blocks with discontinuities is very complex and it is generally not adequate to simply use un-modified laboratory-based measurements of rock properties within models which try to capture the global rock mass behaviour. The mechan-ical properties of intact rock and discontinuities can be determined in the laboratory by triaxial and direct shear methods. In this study the equivalent strength and deformability parameters of a real dam foundation, those of the Surqawshan Earth Dam in Iraq, were predicted using the Distinct Element Method (DEM). The results were compared with those obtained using the Rock Mass Rating and GSI systems. 1 Introduction One of the most challenging tasks in rock mechanics is the accurate evaluation of deformability and strength characteristics of jointed rock masses. A reliable estimation of the strength and deformation properties of a jointed rock mass is required in order to design dams constructed on jointed rock foundations safely and economically. The direct in-situ measurement of the mechanical properties of a rock mass is very expensive and time consuming (Zhang 2005, Zhang & Einstein 2004). At-tempts to characterise large-scale rock mass properties in the laboratory are seldom undertaken due to the high cost, the difficulty of dealing with large samples in the laboratory, and the time required (Hoek 1983). The mechanical properties of intact rock and discontinuities can be determined in the laboratory by triaxial and direct shear methods. However, the in-situ interaction between intact rock blocks with discontinuities is very complex and it is generally not adequate to simply use un-modified laboratory-based measurements of rock properties within models which try to capture the global rock mass behaviour. Numerical modelling provides a method that can help understand how laboratory-based measurements of rock properties relate to full-scale predictions of rock mass behaviour. The aim of this paper is to predict the equivalent strength and deformability parameters of a real dam foundation of the Surqawshan Earth Dam in Iraq using the Discrete Element Method (DEM) and two rock mass classification systems (RMR and GSI). The Universal Distinct Element Code (UDEC) from Itasca (Itasca 2011) was used in this work.
- North America (0.69)
- Europe > United Kingdom > England > Nottinghamshire > Nottingham (0.16)
- Asia > Middle East > Iraq > Kurdistan Region (0.16)
Air-Silicone Oil Flow Around a Vertical to Horizontal 90° Bend
Omar, R. (University of Nottingham) | Azzopardi, B. (University of Nottingham) | Hewakandamby, B. (University of Nottingham)
Abstract The main aim of this work is to investigate the effect of vertical to horizontal 90° bends on the structure and the frequency of the flow. The paper describes how the flow structures in the vertical section develop as it moves downstream the mixing section. It also highlights the effect of centrifugal force on slugs passing around the bend. Finally the flow development downstream the bend and how it alters as it goes around the bend predominantly forming stratified and slug flow is discussed. Introduction Most of the process industries have long pipe lines to transport the process fluids from one place to another. These pipelines have bends to change the orientation of the pipes as warranted by the layout of the process equipment and vessels. Single phase flows in such pipelines have been studied and a good understanding of the flow behaviour has been established making hydraulic designs robust and trustworthy. However, two phase flows that occur in transportation of oil and gas from wells to the production platforms or boiler tubes in power generation are complex and the development of such flows around bends were not well understood. The complexity of the flow behaviour is increased due to the effects of centrifugal force induced by curvature of the bend and the existence of the two phases with significantly different densities. As the fluid passes through curved pipes or bends, a considerable centrifugal force is applied to the mixture forcing it to separate. Separation is affected by the orientation of the bend giving rise to complications such as void fraction fluctuation and formation of dryout zones. The effects of the bends on the two phase flow is a common issue in a wide range of industrial applications, nevertheless low number of studies is available on this subject compared to single phase flow around bends. Several correlation were proposed to estimate the pressure drop around bends for single phase flows including the work of Ito for turbulent [1] and laminar flow [2]. Several attempts to predict the additional pressure drop due to the two phase flow around bends have been reported, specially the work carried out by Chisholm in a series of papers [3–6]. Azzi et al.[7] critically evaluated the available correlation used to predict the pressure drop in bends for two phase flows with Newtonian liquid phase. They emphasised the inconstancy of most of the equations especially at zero bend angle and zero mass flow rate where the pressure drop should be equal to straight pipe and approaching zero velocity respectively. Ultimately B-type correlation given by Chisholm [5] was considered the most suitable correlation for two phase flows.
Continuum and Discontinuum Modelling of Gravity Dams On Jointed Rock Foundations
Alshkane, Y. M. (University of Nottingham) | Marshall, A. M. (University of Nottingham) | Stace, L. R. (University of Nottingham)
Abstract There are many types of commercial software packages available that can be used to model a dam structure and its underlying jointed rock foundation. In this paper, results are compared between a continuum model (FLAC) and a discontinuum model (UDEC), in order to evaluate which code gives the most realistic prediction. The results of this research are compared with the existing conventional analytical methodology which is based on limit equilibrium theory. It is concluded that both codes give similar results to the conventional theoretical approach as long as the rock foundation blocks are not rotated by the stress regime created by the dam and reservoir. However, this similarity was found to depend on the joint strength. As the joint strength is reduced, UDEC was found to provide a better representation of the behaviour of a jointed system and arguably a more realistic prediction of the stress distribution under the dam. 1. Introduction The construction of a safe and economic dam requires a detailed understanding of the geotechnical environment in the area surrounding the dam location. Most historical dam failures are related to deficiencies in the dam foundation due to the presence of jointing in the bed rock. There are various publications relating to dam incidents, such as ICOLD (1974, 1983, 1995) and Douglas (2002). According to these, about thirty percent of incidents occurred due to some deficiency of the rock foundations. For example the Austain Dam (also known as Byless Dam) failed because of sliding between sandstone and shale layers (Martt et al., 2005) and the Malpasset Dam failure was a result of open joints upstream of the dam and an inactive fault downstream (Jansen, 1988). Continuum software packages have been extensively used to analyse and design dams on rock mass, although the rock mass is discrete and its behaviour depends on the joints and the intact rock. One of these packages is FLAC (Fast Lagrangian Analysis of Continua) (Itasca, 2008), which is a 2D explicit finite difference program. Recently the discontinuum approach has gained popularity in geomechanics, especially in mining, tunnelling, and slope stability problems. UDEC (Universal Distinct Element Code) (Itasca, 2011) is a discontinuum software code available for analysing geotechnical problems (Cundall, 1980). UDEC is a 2D distinct element, explicit finite difference program that treats a medium as a collection of discontinuous shapes that interact with each other in space. It is argued that the most powerful tool available to study the rock mass under a dam is the distinct element method because it is capable of modelling the stresses between rock blocks and flow through discontinuities (joints and faults) within the rock mass (Gimenes and Fernández, 2006; Bretas et al., 2013). It should be noted, however, that FLAC can also model discontinuities using interfaces, but this takes up considerable computational time so its use is limited to a few joints within the rock mass. Also, the flow cannot be modelled through the joint.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.54)
- Energy > Oil & Gas > Upstream (0.68)
- Government > Regional Government > North America Government > United States Government (0.46)
- Government > Military > Army (0.46)
A Soil Model Considering Principal Stress Rotations
Yang, Yunming (University of Nottingham Ningbo China) | Yu, Hai-Sui (University of Nottingham)
ABSTRACT This paper presents an elastoplastic soil model considering the principal stress rotation (PSR), which occurs in many geotechnical engineering problems such as in offshore foundations under wave loading. The model is developed on the basis of a well-established kinematic hardening soil model using the bounding surface concept. The significance of including the PSR in soil models is presented. The model can consider the PSRs under multiple directions, and features relatively simple formulations and easy numerical implementations. Model predictions under one and multiple PSRs are compared, and the latter leads to a larger damage to soils than the former.
Determination of Limits to Production in THAI
Greaves, M.. (University of Bath) | Dong, L. L. (University of Bath) | Rigby, S. P. (University of Nottingham)
Abstract The operational production period in Toe-to-Heel Air Injection (THAI) has been investigated via numerical simulation of a field scale section of the Conklin THAI pilot in the Athabasca Oil Sands. THAI is an advanced horizontal well development of the in situ combustion process for heavy oil recovery. It operates as a ‘short-distance’ displacement process, and is being applied to bitumen and heavy oil reservoirs. Breakthrough of oxygen into the production well is predicted to occur after 10.8 years of oil production. This occurs during the declining oil rate period, which follows a sustained period of constant rate production. Prior to oil rate decline, the oil recovery factor was 63 %. High combustion temperatures aid continued expansion of the steam bank, maximizing oil recovery. Economic and also safety factors determine the ultimate decision point, concerning termination of operations. On the one hand, maximum oil recovery is determined by longer operation time, but this is also influenced by safety considerations, principally, the approach to oxygen breakthrough. Terminating the process early maximises the financial rate of return, but at the expense of total oil recovery. Reduction in the oil price is probably the most significant factor affecting profitability, but this also depends on timing and degree of financial risk.