PRISM :: Browsing by Author "Wong, Ron"

Browsing by Author "Wong, Ron"

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Open Access
An experimental study on time-dependent behaviour of reconstituted clayey soils in 1D and triaxial compression
(2018-09-26) Wickrama Kaluthota Hewage, Rajitha Eranga Wickramage; Wong, Ron; Hayley, Jocelyn; Wan, Richard; Maini, Brij; Siddiqua, Sumi
Accurate assessment of the safe performance of geotechnical structures against the time-dependent strength-deformation behaviour of soils relies on the knowledge acquired from laboratory and field experiments. Therefore, the focus of this research is to experimentally investigate the role of stress history, soil properties and loading system in the time-dependent strength-deformation behaviour of reconstituted clayey soils. The experimental program consists of oedometer and triaxial compression tests on compacted lightly overconsolidated natural soils (high plastic Regina clay and low plastic Calgary till) as well as on artificial soil mixtures made by mixing pure kaolinite or bentonite with crushed Opal, silt or Calgary till. Results of multiple-stage oedometer tests show that vertical stress level, clay content, size of the coarse particle, coarse particle type, clay type, and liquid limit affect the secondary compression behaviour of oils. Results of constant rate of strain tests in oedometer and triaxial conditions show that at a given strain level, faster strain rates always result in a higher effective vertical stress or deviatoric stress value for high plastic Regina clay. Thus, the behaviour is considered as isotach. However, low plastic Calgary till shows isotach behaviour only under overconsolidated or unsaturated conditions. Further, strain rate effect on shear strength is found to increase with liquid limit, OCR value, matric suction, and absolute magnitude of strain rate. In both oedometer and triaxial conditions, the ratio between relaxed stress at any time and the stress level at the beginning of the relaxation test is found to be linear with the logarithm of time after an initial time period. These linear segments are approximately parallel for stress relaxation tests conducted within or closer to the NC region/post-peak region of the stress-strain curve a soil. The gradient of these parallel segments is found to be independent of the soil structure and confining pressure but depends on the test condition and degree of saturation. Intercepts of fitted lines to these parallel segments can be used to correlate strain rate, stress relaxation behaviour and pre-consolidation pressure. Keywords: Time-dependent, secondary compression, stress relaxation, shear strength, isotach
Open Access
The Application of Fishbone Wells in Steam-Assisted Gravity Drainage
(2022-09) Edafiaga, Benjamin; Gates, Ian; Gates, Ian; Wong, Ron; Chen, Shengnan; Haddad, Amin; Hejazi, Hossein; Chen, Zhangxing
Apart from cost, major challenges facing the recovery of bitumen from Canadian oil sands are the amount of energy utilized per volume of bitumen recovered as well as the amount of greenhouse gas (GHG) emitted to the environment. The situation is even worse in reservoirs that are considered to be challenging or difficult-to-produce due to the reservoir geology. Steam-assisted gravity drainage (SAGD) is the primary in-situ recovery technique for bitumen recovery in Northern Alberta, Western Canada. Within the reservoir, steam chamber conformance is a major control on the efficiency, economic performance, and GHG emissions intensity of the process. There is a search for ways to significantly reduce the costs and emissions of SAGD. Multilateral wells possess the potential to contribute towards this goal. To date, different theoretical designs of multilateral wells have been proposed in literature. One of the most common designs studied is the fishbone well configuration. This configuration has large reservoir contact and thus enhances the productivity of the well. While the merits of the application of multilateral wells are well documented in lighter oil systems, an understanding of the best operating conditions for the use in oil sands reservoirs is poorly understood. The research documented in this thesis examines in detail how fishbone multilateral wells can be used to improve the performance of SAGD. In summary, the results demonstrate that fishbone well are able to improve steam chamber conformance and ultimately minimize cumulative steam-oil ratio (cSOR), maximize ultimate bitumen recovery, improve net present value (NPV), and reduce GHG emissions. Therefore, fishbone multilateral wells should be considered for future SAGD operations.
Open Access
Application of Machine Learning in Methane Emissions Modelling
(2022-07) Luo, Ran; Gates, Ian; Hu, Jinguang; Chen, Nancy; Siegler, Hector; Wong, Ron; Idem, Raphael
Methane emissions reduction activities are vital for reducing greenhouse gas emissions in the oil and gas industry. The Alberta Energy Regulator (AER) has been collecting air quality data throughout the province since 1986. Although the AER data is available to the public, the analysis of this data has not been thorough. Furthermore, there are many papers on reported emissions, and as yet, it remains unclear how to use and analyze this time series data. Machine learning is a state-of-the-art and effective method to forecast and understand methane emissions from the oil and gas sectors. The research documented in this thesis examined the methane emissions data from multiple monitoring stations in time by building machine learning models for prediction performance comparison. The first study compared Autoregressive Integrated Moving Average (ARIMA), Fully Connected Neural Network (FC-NN), and Long Short-Term Memory (LSTM) neural networks regarding total hydrocarbon non-methane hydrocarbon in general. The second study expanded the research by adding climate variables to build LSTM models to learn deep feature relationships between temperature, wind speed and wind directions regarding the methane concentration data. The third study examines the prediction performance of Gated Recurrent Units, Stacked LSTM, LSTM and Bidirectional LSTM neural networks with different scales of data for training to compare forecasting performance. The analysis of the experiments reveals 1. The LSTM neural network model provides better predictive performance than the other methods. With respect to the data itself, the average methane concentrations measured at the majority of Alberta airshed stations are higher than the global methane average. In addition, the methane concentration data itself exhibits both increasing and decreasing trends depending on the station. 2. Extra ambient climate variables can improve the predictive performance of the LSTM model: temperature improves the predictive performance of the methane concentration more than that of wind speed and direction. 3. GRU performs better when trained with shorter datasets, while the Stacked LSTM and the LSTM slightly outperform GRU and BiLSTM when training with more historical data. Also, more training data does not necessarily mean a significantly better prediction model but more training time. The results provide insights for the use of Predictive Emissions Monitoring System (PEMS) for estimating methane concentration emission data.
Open Access
Behaviour and design of slender masonry walls at full- and half-scale subject to axial eccentric loads
(2023-08) Iskander, George Sami Aziz Salama; Shrive, Nigel; Wong, Ron; Duncan, Neil
The behaviour of slender concrete masonry walls is poorly understood. This is particularly evident by the treatment of such walls in the Canadian masonry design standard, CSA S304-14. Many researchers have noted the poor accuracy of CSA S304-14’s provisions and the need for more experimental data. A major limiting factor to building and testing walls is their size and the quantity of materials used. This limitation can be overcome by using half-scale walls – however, it must first be proven that scale effects do not influence the results obtained. Of further utility would be a verified finite-element model to predict wall failure loads and modes with a high degree of confidence. Towards these ends, twelve masonry walls, six at full-scale and six corresponding half-scale walls, were built and tested under an axial load with an eccentricity of 1/3 of the wall thickness; single curvature moment was applied. Digital image correlation (DIC) was used to acquire lateral displacement data; its implementation in this study is presented. Specimen handling procedures are also presented. Wall strengths, lateral displacement profiles and behaviour were recorded and are presented. Experimental results show that size effect does not influence the behaviour and strength of slender concrete masonry walls at half-scale. Experimental results are used to discuss shortcomings in CSA S304-14’s treatment of wall effective stiffness. A verified finite element model was also used to investigate the failure load and mode of 80 hollow masonry walls, with varying effective height to thickness ratio, eccentricity, and inclusion of initial geometric imperfection. Numerical results are used to determine when the inclusion of geometric imperfections impacts numerical predictions, and to determine wall failure modes for various parametric combinations. The model is also used to discuss adjustments to clauses in CSA S304-14 related to minimum primary moment and hollow masonry wall axial strength.
Open Access
Characterization of damage processes in Montney siltstone under triaxial compression using acoustic emission and diagnostic imaging
(Oxford University Press, 2021-11-04) Jia, Suzie; Wong, Ron; Eaton, David
Crack nucleation and rock failure processes in a fine-grained siltstone (Montney Formation) under triaxial compression are investigated using combined diagnostic techniques, including ultrasonic-wave measurement, acoustic-emission (AE) monitoring, computed tomography (CT) scanning, and thin-section imaging. The sample displays a weak-to-moderate inherent seismic anisotropy and noticeable stress-induced anisotropy prior to failure. No AE event was detected until the applied axial stress reached 95% of the peak value. The signal-to-noise ratio is relatively low, however, and detectable AE events are more diffuse than those observed in highly brittle rocks. The AE locations correlate with a shear fracture zone imaged by CT scanning. AE moment-tensor analysis reveals that events with larger relative magnitudes are characterized by high volumetric (tensile or compressive) components, and the initiation of the failure zone is dominated by combined shear-tensile failure. Stress inversion of the AE events with high tensile components is in good agreement with the known applied stress. Microscopic imaging of thin sections from the failed sample shows that the failure zone is an en echelon structure consisting of a major fracture with branching micro and minor cracks. This failure mechanism is consistent with a shear-tensile source mechanism and is interpreted to be associated with the fine granular structure and mineral composition of Montney siltstone.
Open Access
Characterization of tight and shale unconventional gas reservoirs using low field NMR
(2023-01-26) Solatpour, Razieh; Kantzas, Apostolos; Torabi, Farshid; Aguilera, Roberto; Clarkson, Christopher; Chen, Shengnan; Wong, Ron
Unconventional petroleum resources, especially tight and shale reserves, constitute an increasing frontier of reserves additions as conventional production declines. In these sources, reservoir characteristics have significant value in reserve estimation and flow modelling. These characteristics are challenging parameters to measure. On the other hand, oil and gas sectors are continually looking for ways to do more with less environmental impact and greater operational efficiency. Nuclear Magnetic Resonance (NMR) offers fast and non-disruptive detection of the reservoir samples properties. The purpose of this research is to investigate the interactions between tight and shale rocks with hydrocarbons using NMR technique. This thesis mainly presents routine and new experimental and numerical methods of measuring porosity, permeability, residual saturations, and excess and absolute adsorption isotherms. The experiments were conducted on different porous media such as shale cores, tight sand cores, activated carbon, and sandpacks at pressures up to 7 MPa. In this thesis, for 150 cores, permeability was estimated using all existing NMR permeability correlations. In addition, irreducible saturations were presented for these cores. A new method to obtain residual saturation using the area under the NMR relaxation distribution curves was introduced. Permeability and irreducible saturation models are compared based of their standard error deviation from the independently measured ones. For organic porous media, the NMR decay curve of hydrocarbons exhibited a logarithmic behaviour at early times. Based on this observation, a new method of obtaining absolute adsorption was developed. The time when the decay curve shifts from logarithmic to multi-exponential behaviour was defined as sorption cut-off time. Adsorption isotherm hysteresis of methane in Duvernay shale samples was demonstrated using the newly developed method. In this research, for the first-time Low-Field NMR relaxometry with a frequency close to logging tools directly and without the use of correlations is used for quantitative determination of adsorption isotherms of methane in shale reservoirs. Isotherms derived by the new method better described the physical behaviour of hydrocarbon in organic porous media as it captures the effect of phase transition and measures critical pressure in organic porous media, which is different than the ones in non-organic porous media. Moreover, with this new fractal model, total hydrocarbon in place, adsorbed, and free hydrocarbon can be estimated from a single NMR experiment. This thesis is beneficial in understanding existing tight and shale reservoir characterization methods and introduces more advanced and reliable techniques to measure the properties of these reservoirs. In chapter 3 to 7 of this study, currently available methods of tight and shale reservoir characterization are presented. Then a new approach is provided for each case which is less computationally demanding, and calculations are easier to perform. Moreover, in most scenarios only a single NMR measurement is needed.
Open Access
Detecting Vortex-Induced-Vibrations of Flexible Pipes using Internal Pressure Sensors
(2024-05-09) Webber, Scott; Morton, Chris; Martinuzzi, Robert; Bisheban, Mahdis; Wong, Ron
The internal flow pressure response of a fluid-conveying-pipe undergoing lateral oscillations is investigated experimentally using a new pipe flow loop facility. The facility is capable of actuating 1/2" PVC pipe up to 1 Diameter, 4 Hz. and directly measuring the corresponding internal fluid pressure. The dependence of the internal pressure response on mean internal flow velocity, oscillation frequency and amplitude, oscillating span length, and downstream outlet length is investigated for a limited range of those parameters. Simplified models are developed based on control volume stretching and viscous oscillatory pipe flows and are compared to the experimental data. Both models and experimental data suggest a sinusoidal response pressure gradient ∂P/∂x (t) with frequency 2f_in and amplitude proportional to f^2_inA^2_in/L, with f_in, A_in, and L representing the span oscillation frequency, oscillation amplitude and length, respectively. Further experimentation is required to adjust the models empirically to the data. The generated internal pressure is used as a target signal amidst background pressure noise to investigate the behaviour of a power spectrum sensor used to detect pipe oscillations via internal pressure measurements.
Open Access
Determination of Mode I Fracture Toughness, Tensile Strength and Adhesion of Compacted Clays
(2018-09-12) Cao, Keda; Wong, Ron; Wan, Richard; Dong, Mingzhe
Tensile strength and fracture toughness are two parameters used to define the ability of resisting fracture under tensile stresses. Adhesion of clays to metals is the strength of soil-metal interface. These properties of cohesive soils are fundamental and essential for geotechnical problems. Two types of compacted clays were used in this research — Calgary till and Regina clay. The fracture toughness KIc and tensile strength σt of two clays were measured by straight notched disk bending (SNDB) method and uniaxial direct tensile test, respectively. Results showed that the variations of σt with respect to moisture content and dry density were very similar with that of KIc. A strong positive correlation between these two properties was found. The tensile strength of compacted clays was curve fitted based on a double-porosity concept which considers the water among micropores and macropores in clay structure and their contribution to the strength of soils. The adhesion of compacted clays to stainless steel was measured using a modified direct shear box test. To obtain the adhesion factors, the adhesion was correlated with unconfined compressive strength of compacted clays. The effects of moisture content and pre-consolidation pressure on adhesion were investigated.
Open Access
Effect of GNSS Receiver Signal Tracking Parameters on Earthquake Monitoring Performance
(2016) Clare, Adam; Lachapelle, Gérard; Lin, Tao; Petovello, Mark; Wong, Ron
This research focuses on the performance of GNSS receiver carrier phase tracking loops for earthquake monitoring systems. An earthquake was simulated using a hardware simulator; position, velocity and acceleration displacements were obtained to recreate the dynamics of the 2011 Tohoku earthquake, Japan. Using a software defined receiver, various tracking bandwidths and integration times were tested. Using the phase lock indicator and carrier-to-noise ratio as metrics, an adaptive carrier tracking loop was successfully designed and tested to maximize performance for this application. Four different simulations were done to assess the performance of the adaptive carrier tracking loop. Two simulations with carrier-to-noise ratios greater and less than 35 dB-Hz were done using the original dynamics of the 2011 Tohoku earthquake. The other two simulations tested were the dynamics of the same earthquake scaled by a factor of 10, with carrier-to-noise ratios greater and less than 35 dB-Hz.
Open Access
Effect of High Temperature on Physical and Mechanical Properties of Clay Shales (Caprock)
(2022-06-03) Dovletov, Shamammet; Wong, Ron; Khoshnazar, Rahil; Wan, Richard
The complex structure of heavy crude oil and bitumen requires enhanced oil recovery methods such as cyclic steam stimulation and steam-assisted gravity drainage to recover effectively. These methods are operated at high temperature ranges. Thus, it is crucial to understand the effect of high temperatures on such operations. This thesis aimed to investigate the changes in physical and mechanical properties of clay shale caprock due to pre-heating under high temperatures. For this purpose, intact clay shale cores were recovered from a site near Long Lake in Alberta. To investigate the effect of pre-heating on clay shale's strength and deformation characteristics twelve samples were trimmed and prepared. Samples were pre-heated up to 20, 150, 300 and 600 °C and thereafter cooled down to ambient temperature naturally. The variation of mechanical properties of clay samples due to the pre-heating was examined in triaxial compression tests. Changes in the composition and crystalline structure of the clay samples were determined through X-ray fluorescence and X-ray diffraction analysis. The experimental results indicated clay samples becoming stiffer (with increased Young’s modulus and lowered Poisson’s ratio) with increasing temperature. Also, the friction angle and cohesive strength of the clay sample increased with temperature. These findings indicate an increasing trend in the mechanical strength of clay samples with temperature. The failure of the clay samples at low confining pressure was mainly due to shear dilation, while compression was the cause of failure at higher confinement pressure.
Open Access
Effect of Temperature on Two-phase Oil/Water Relative Permeability under SAGD Conditions
(2020-06-25) Esmaeili, Sajjad; Maini, B. B.; Sarma, Hemanta Kumar; Dong, Mingzhe; Kantzas, Apostolos; Wong, Ron; Srinivasan, Sanjay; Harding, Thomas Grant
The successful implementation of any thermal recovery process in heavy oil reservoirs for the enhanced oil recovery requires some indispensable information related to the multi-phase fluid flow characteristics under high-temperature and high-pressure conditions. The relative permeability is an essential element which is required to model the flow performance within porous media. The two- and three-phase relative permeability affect the fluid flow velocity as well as the pressure gradient profile and saturation profile within the oil reservoir during the water flooding or steam and gas flooding. In order to predict the flow performance in thermal recovery processes, in which the temperature changes with position and time, the change of two- and three-phase relative permeability with temperature should be considered. Although numerous researchers have previously studied the variation of relative permeability with temperature since mid-fifties, this issue is still unresolved and remains challenging. Moreover, many contradictory results associated with the temperature’s impact on relative permeability reported in the literature and the relative scarcity of available data points for heavy oil and bitumen systems under thermal recovery conditions make this issue very critical for a reliable analysis. The aim of this research was to comprehensively investigate the effect of temperature on two-phase oil/water relative permeability in different rock-fluid systems, especially for Athabasca bitumen. In this regard, a reliable rig was developed to include the necessary elements to measure the steady- and unsteady-state relative permeability of two-phase systems in unconsolidated sand more accurately. This study was carried out in four phases. As per our objectives, the empirical correlations for two-phase oil/water relative permeability curve characteristics as a function of temperature in different rock-fluid systems were proposed first based on data reported in the literature. In addition, a new data-driven model for two-phase oil/water relative permeability in heavy oil/sand systems was also developed based on the experimentally measured data points. In the second phase, the impact of temperature on two-phase oil/water relative permeabilites was assessed over a wide range of temperatures from 23o to 200 °C in a clean viscous oil/sand system using the unsteady-state approach. In the third phase, the clean viscous oil phase was replaced by an ultra-heavy viscous oil, Athabasca bitumen. In this system, the effect of temperaturet on the two-phase relative permeabilites was evaluated using several core flooding experiments within a temperature range of 70-220 °C under the SAGD pressure (i.e., 2760 kpa). Both steady-state and unsteady-state relative permeability measuring techniques were utilized. In the final phase of this research, a solvent-aided system was employed for the relative permeability measurement at high temperatures to assess the effect of temperature on relative permeability of a diluted Athabasca bitumen/water/sand system in the same temperature range that was used for the unaltered Athabasca bitumen/water systems. Moreover, interfacial tension (IFT) and contact angle measurements were carried out for all systems at different temperatures to evaluate any change in fluid-fluid and rock-fluid interactions with temperature. The history matching of displacement tests was conducted using a reservoir simulator developed in-house. The experimental results revealed that the relative permeability curves in a clean viscous oil/deionized water/sand were practically independent of temperature, even though the viscosity ratio dramatically reduced at higher temperatures. Furthermore, the reduction of IFT to less than one order of magnitude and a small variation in contact angle at higher temperatures were not enough to alter the relative permeability. In contrast to this clean system, the unsteady-state relative permeability to Athabasca bitumen and water was a strong function of the temperature. At higher temperatures, the endpoint relative permeability to water considerably increased as well as the true residual oil saturation decreased significantly. Moreover, the irreducible water saturation slightly increased and endpoint relative permeability to oil also revealed an increasing trend. The steady-state relative permeability curves demonstrated the same behavior as the unsteady-state relative permeability curves at higher temperatures. A reduction in IFT and contact angle (i.e., a shift towards increased water-wetness) were also observed for this system with increasing temperature. The results obtained from several isothermal core flooding experiments using diluted bitumen at different temperatures confirmed that the two-phase relative permeability curves were still temperature-sensitive; however, the effect of temperature on relative permeability was less pronounced in diluted bitumen systems containing 9 wt. % of n-hexane, in comparison with unaltered bitumen systems. Again, a reduction in IFT and contact angle of a smaller level compared to the unaltered bitumen was captured at increased temperatures in this study. Since commercial reservoir simulators often consider the relative permeability curves to be insensitive to temperature, we anticipate that the temperature-dependent relative permeability model developed in this research can assist reservoir simulators to more effectively predict the flow performance in TEOR processes, especially for Canadian bitumen in the future.
Open Access
Experimental and Numerical Exploration of Electromagnetic-Induced Fracturing of Clay-Shale
(2022-09) Chen, Xiaolin; Wan, Richard; Priest, Jeffrey; Wong, Ron; Okoniewski, Michal; Zhou, Qi; Chan, Dave
The rapid electromagnetic (EM) heating of saturated clays and shales offers a potential means of selectively fracturing interbedded shales, and thereby enhancing oil production while maintaining the caprock integrity of shaley oil sand reservoirs during thermal production process. It is hypothesized that fracturing will occur in an extremely low permeability porous medium due to a large increase in pore fluid pressure by electromagnetic wave heating. As opposed to classical resistive heating, the EM heating of saturated clays/shales is mainly achieved by the interaction between radiating electromagnetic waves and polar water molecules. The above provides the backdrop for the thesis which aims at understanding the underlying fracture and thermal stress mechanisms of EM heating in a geomaterial. As such, comprehensive laboratory experiments are conducted in a specially designed EM heating apparatus. Challenges of the experimental endeavor are highlighted, given the susceptibility of measurement sensors with electromagnetic radiation. Four scenarios of tests are performed on kaolinite clay samples, a surrogate for clay-shale, whose basic properties are measured prior to EM heating. The use of kaolinite samples allows for the conduct of repeatable tests and provides a benchmarking for future tests on actual clay-shale core samples. Results of undrained tests at different confining conditions show that the clay will lose its structural integrity when the thermally induced excess pore pressure in the sample is higher than its tensile strength plus confining pressure. Alongside with the above lab experiments, a two phase (water-steam) fully coupled Multiphysics (EM wave propagation/thermal/fluid/mechanics) model is developed to study the major mechanisms of rapid EM heating. The finite element method is employed with a segregated numerical strategy to solve this highly nonlinear problem using a commercial software COMSOL Multiphysics. The simulation results indicate that pore water pressures develop mainly due to the high contrast between the fluid and solid phase coefficients of thermal expansion. Numerically predicted zones of fracture initiations and patterns are verified against experimental observations using a Mohr-Coulomb failure envelope combined with a tension cutoff.
Open Access
Experimental Investigation and Modelling of Vortex-Induced Vibrations near Scoured Boundaries
(2024-06-05) Hardika, Michel Supernikovic; Morton, Chris; Martinuzzi, Robert; Limacher, Eric John; Wong, Ron
An experimental investigation into the vortex induced vibrations (VIV) of a circular cylinder under scour conditions was conducted. These conditions replicate river crossings of exposed pipelines. The thesis focuses on developing a model to predict the VIV response, and the characterization and flow evolution of the scour VIV response. The development of the model involves the calibration of a coupled two-equation model for a large VIV dataset from a one degree of freedom (1DOF) elastically mounted rigid cylinder in an open free stream that spans across a range of mass, damping, and flow velocities. This experiment was conducted in a water channel where cylinder displacement and force data were collected. The model adequately predicts the lock-in reduced velocity range and oscillation amplitudes. Its empirical coefficients are related to the mass, damping, and flow velocity, improving the prediction capability over previous models. A second data set was collected to address the characterization of VIV response and flow development under scour conditions. In particular, the experiments had one structural configuration with the 1DOF cylinder placed adjacent to different rigid flat and curved boundaries based on the profiles found in past scour studies. The collected data includes displacement, force, and Particle Image Velocity (PIV) measurements across a wide range of flow velocities. The data was processed to produce oscillation amplitude and lift responses, oscillation frequency contour maps, and a Low Order Representation (LOR) of the flow field through a Proper Orthogonal Decomposition (POD) analysis. The results show that the boundary modifies the VIV response in terms of lock-in range, oscillation amplitude, lift, and the appearance of new regimes when compared to the open free stream case. The LOR flow fields reveal the boundary layer coupling with the formation and shedding timing of the cylinder’s vortices, leading to the changes in the response. The results of this investigation aid in understanding the possible oscillation characteristics that submerged structures such as exposed pipelines in riverbeds exhibit. These characteristics inform the design and monitoring of these systems by relating the flow and structural conditions to the expected oscillation response.
Open Access
External and Internal Corrosion and Its Control of Natural Gas Pipelines
(2019-12) Qian, Shan; Cheng, Y. Frank; Li, Leping; Wang, Ruisheng; Oguocha, Ikechukwuka; Wong, Ron
Natural gas pipelines suffer from both external and internal corrosion during their service life, which may result in dramatic consequences. In this research, external corrosion of X52 pipeline steel under direct current (DC) interference was investigated in a simulated soil solution. Corrosion acceleration by DC was quantitatively determined as a function of DC current density. DC was found to shift the cathodic protection (CP) potential to positive and negative directions in the anodic and cathodic zones, respectively, on the pipelines, resulting in either corrosion enhancement or hydrogen evolution at the zones. The effect of DC on properties and performance of fusion bonded epoxy (FBE) coating applied on pipelines was studied. The presence of DC interference facilitates water permeation into the coating due to the altered molecular structure and decreased the coating resistance for corrosion protection. Furthermore, corrosion of X52 pipeline steel under dynamic DC interference was investigated. Dynamic DC further accelerates the steel corrosion compared to static DC at specific DC current densities. It is believed that the alternating current (AC) component included in the pulse DC contributes to the corrosion reaction. With increase in the DC pulse frequency, corrosion rate of the steel decreases. The wave form of the dynamic DC does not obviously affect the steel corrosion. Internal corrosion of X52 pipeline steel was investigated in CO2-containing thin layers of solution, simulating the actual corrosive environment generated in the interior of natural gas pipelines. A mechanistic model was developed to explain the internal corrosion of wet gas pipelines. With the decrease of the solution layer thickness, the corrosion rate of the steel reduces. An elevated temperature accelerates the corrosion reaction kinetics, and generates a compact and homogeneous FeCO3 film at the same time. The presence of acetic acid increases the steel corrosion, while the methanol reduces corrosion rate of the steel. For external corrosion control, a micro/nanostructured ZnO-alkylamine composite coating was developed by electrodeposition and anodization to possess multiple functions. The optimal coating film is superhydrophobic, with the water contact angle up to 158o. The coating possesses a good corrosion resistance and excellent self-cleaning performance and a strong anti-adhesion to pseudomonas aeruginosa bacteria. For internal corrosion control, the inhibition performance of imidazoline (IM) and sodium dodecylbenzenesulphonate (SDBS) inhibitors and their synergism on corrosion of X52 steel in CO2-saturated chloride solutions was investigated. The synergistic effect of the two inhibitors enhances the corrosion inhibition performance, compared to the inhibitors acting independently. The adsorption of both inhibitors on the steel is chemisorption, following the Temkin adsorption isotherm.
Open Access
Geological CO2 Storage Modelling Using Micro-Gravimetry
(2016) Kabirzadeh, Hojjat; Kim, Jeong Woo; Sideris, Michael G.; Gao, Yang; Elhabiby, Mohamed; Wong, Ron; Pagiatakis, Spiros
The invention of the portable iGrav superconducting gravimeter has provided unique precision and stability to monitor the subtle gravity field variations due to injection of CO2 into deep geological storages. According to the data collected over six months of continuous measurements by the iGrav001 at the University of Calgary, an accuracy of better than 1 µGal is achievable after corrections for environmental interferences, while the instrumental drift remains negligible. The combination of temporal observations of the iGrav along with observations of relative spring gravimeters, obtained in special network configurations, can lead to accuracies of 1-2 µGal for the gravity variations between two epochs before and after CO2 injection. In almost all previous CO2 storage modelling studies, the porosity change effect on the gravity signal has been assumed to be negligible. In this study, geological storages are divided into two major categories: unconfined and confined reservoirs. In the unconfined reservoirs, injected CO2 replaces the ambient fluid, causing a negative density anomaly in the reservoir and a negative gravity signal with negligible deformation at the ground surface. Confined reservoirs, on the other hand, experience a volumetric change and the injected CO2 fills the excessive porosity, causing a positive gravity signal representing the attraction of the injected CO2, and a positive ground surface deformation signal along with the associated free-air gravity effect. Dependency of gravity and ground deformation signals on variable properties, such as injected CO2 mass and density, along with reservoir depth and size, is examined by forward modelling for both confined and unconfined CO2 reservoirs. In addition, while inversion of the unconfined CO2 reservoirs obeys the conventional gravimetric modelling formulation, a novel inverse modelling formulation is established for confined reservoirs. A relationship is developed between the density changes and the fractional volumetric changes due to the CO2 injection in the confined reservoirs, and a linear inversion is implemented to estimate fractional volumetric changes using both ground deformation and gravity observations jointly. The developed inverse modelling methodology is evaluated using several synthetic case studies.
Open Access
Influence of Particle Size Distribution on Mechanical Behavior of Hydrate-bearing Sands
(2021-10-27) Zafar, Raheel; Priest, Jeffrey; Hayley, Jocelyn; Wong, Ron; Khoshnazar, Rahil
Gas hydrates are natural ice-like, crystalline solid compounds that form in both permafrost and deep-water oceanic sediments. The large volumes of methane gas stored in hydrates make them an ideal resource for the world’s future energy demands. Hydrate-bearing coarse-grained sand sediments have great potential for commercial exploitation due to their high permeability and high hydrate content within pore space. The formation of hydrates significantly increases the strength and stiffness of host sediment and their dissociation directly impact host sediment stability. A recent study on natural hydrate-bearing sediments reported a significant correlation between sediment particle size and its strength and stiffness. Therefore, to ensure sustainable gas production activities, the effect of sediment particle size on the large-strain mechanical response of hydrate-bearing coarse-grained sediments needs to be investigated. This thesis reports on an experimental program that allowed the controlled and homogenous formation of gas hydrates within laboratory synthesized sand specimens and their subsequent laboratory testing to investigate the effect of particle size on their mechanical response. Specimens containing a different proportion of large particle sizes were prepared and their mechanical properties were investigated in two states: base sand (BS) and hydrate-bearing sand (HBS). Results show that the hydrate growth rate appears to be dependent on the particle size of sediment, with a decrease in sand particle size increasing the hydrate growth rate. Triaxial test results show that the strength and stiffness of HBS specimens strongly depend on particle size, hydrate saturation, and applied effective stress. The influence of particle size becomes evident at high hydrate saturations (> 46%). Increasing the proportion of large particles within the sediment matrix significantly increases the strength and stiffness of HBS specimens. The cohesion also exhibits dependency on particle size. An increase in the specific surface areas of sand grains reduces the cohesion of HBS specimens.
Open Access
Measurement and Simulation of Preferential Flow in Frozen Soils
(2019-11) Mohammed, Aaron A.; Cey, Edwin E.; Hayashi, Masaki; Lemieux, Jean-Michel; Bentley, Laurence R.; Wong, Ron
The infiltrability of frozen soils strongly influences the partitioning of snowmelt and hydrological functioning of cold regions. Preferential flow in macropores may enhance infiltration into frozen soil, but flow dynamics are complicated by coupled water and heat transfer processes. Field studies were conducted in the Canadian Prairies to evaluate the dominant mechanisms controlling preferential flow in frozen soils, and the combined influence of soil freeze-thaw and preferential flow on snowmelt-driven infiltration and groundwater recharge. Results showed that preferential flow enabled relatively large amounts of snowmelt infiltration when the soil was still frozen, but that refreezing of infiltrated meltwater during winter snowmelt events progressively reduced soil infiltrability and enhanced runoff generation over subsequent events. Preferential flow allowed meltwater to bypass portions of the frozen soil and facilitated the lateral transport of meltwater between high and low topographic positions and groundwater recharge through frozen ground. Insights gained from field studies were used to develop a dual-permeability model of unsaturated flow in frozen soils that assumes two interacting pore domains (macropore and matrix) with distinct water and heat transfer regimes. This dual-permeability formulation was incorporated into the hydrological model HydroGeoSphere to account for liquid-ice phase change in macropores, such that porewater freezing in macropores is governed by macropore-matrix energy transfer. The model was tested against field and laboratory observations and used to examine the effects of preferential flow on snowmelt partitioning between surface and subsurface flow in frozen soils. Simulations were able to reproduce measured profile-scale infiltration and drainage in frozen soil due to macropores, as well as hillslope-scale partitioning of snowmelt input between runoff, infiltration and groundwater recharge. Incorporating macropore flow and freeze-thaw processes was key to simulating the hydrologic functioning of the prairie grassland landscape, and results highlighted that refreezing of infiltrated water governed by macropore-matrix heat transfer is an important subsurface process controlling runoff generation in frozen soils. This study improves our understanding of, and ability to predict, the effects of preferential flow and freeze-thaw on frozen soil infiltrability, and how these processes dictate the partitioning of snowmelt between surface runoff, soil moisture and groundwater recharge in seasonally frozen landscapes.
Open Access
Modelling In-plane Shear in Partially Reinforced Concrete Masonry
(2018-06-25) Pan, Huina; Shrive, Nigel; Wong, Ron; Sudak, Leszek Jozef
Diagonal cracking is the most commonly reported mode of failure for masonry walls subject to in-plane shear loads. Finite element studies were therefore carried out to seek better understanding of this failure mode by attempting to capture the diagonal shear cracks in unreinforced concrete masonry and partially grouted/reinforced concrete masonry. Some key parameters (such as boundary and loading conditions, axial stress, and wall aspect ratio) were examined in the research. Interaction between axial stress and aspect ratio has been noticed. Diagonal compression “strut” was identified from contour plots of principal compressive stress, and therefore two distinct “strut” widths were proposed to account for strength and stiffness of the wall separately. Last but not least, effect of relative panel-to-“frame” stiffness ratio (represented by effective panel-to-frame modulus ratio in this study) has been observed through modelling in partially grouted/reinforced walls. This is rather an important step toward understanding the failure patterns of partially grouted masonry since this factor has not received much attention in the literature.
Open Access
On Hydraulic Fracturing of Tight Gas Reservoir Rock
(2016) Maulianda, Belladonna; Gates, Ian; Wong, Ron; Mehta, Sudarshan; Moore, Robert; Lines, Laurence; Hawkes, Christopher
Production of shale and tight gas resources is increasing which is helping to counterbalance the conventional gas resource production decline. In 2014, shale and tight gas were 4% and 47% of total Canadian natural gas production, respectively. By 2035, the National Energy Board forecasts shale and tight gas production together will represent 90% of Canada’s natural gas productions. In Canada, shale and tight gas production activities are located mainly in Western Canada Sedimentary Basin (WCSB). The tight gas Glauconitic Formation in the Hoadley Field in Alberta, Canada requires hydraulic fracturing of horizontal well completions because of its low permeability of 0.07 mD. Fracture network drainage volume and enhanced permeability created by the hydraulic fracture and the natural fracture interaction are the major enabler of commercial production. The research documented in this thesis investigates the characteristics of the fracture network or stimulated rock volume (SRV) caused by hydraulic fracturing. Specifically, the dimensions of SRV, permeability, pore pressure, and in-situ stresses are examined during hydraulic fracturing and production. Even though this topic has been examined since the early 2000s, the results provide new techniques to determine SRV properties. Three different approaches were investigated. The first handles the impact of SRV dimensions and Young’s modulus on the SRV effective permeability during hydraulic fracturing by using three-dimensional finite element analysis including an investigation of fracture aperture and spacing within the SRV using a new semi-analytical approach. The second investigates the impact of rock mechanical properties and injected volume during hydraulic fracturing on SRV dimensions using a new analytical model. The third explores a new nonlinear partial differential equation together with rate transient analysis to evaluate how the SRV evolves versus distance and time with a history match of the gas flow rate profile. The results demonstrate that the dimensions and characteristics of the hydraulic fracture network can be estimated for the Hoadley Field.
Open Access
On the Effective Stiffness of Slender Concrete Masonry Walls
(2022-12-29) Bogoslavov, Mihailo; Shrive, Nigel; Sudak, Les; Wong, Ron
The slender masonry wall design procedure in the Canadian Standard for Design of Masonry Structures, CSA S304-14, (2014) has been found to be overly conservative. The calculated effective stiffness term, EIeff, which is used to determine the secondary moment due to wall deflection, was noted as a potentially significant cause of this conservatism. In this thesis, the degree to which the effective stiffness term contributes as a source of error is assessed by analyzing the results from a concrete block wall testing program (Hatzinikolas et al., 1978a) and comparing the recorded lateral wall deflections to the deflections calculated as per CSA S304-14 (2014). The effective stiffness is shown to be particularly underestimated by the procedure in the Standard (leading to overdesign of walls) when a wall is designed to be loaded at a low axial load eccentricity. A more accurate equation for calculating the effective stiffness of a wall as it is being loaded is developed and recommended in this thesis, whereby the effective stiffness depends on the wall’s thickness, critical buckling load and the applied axial load and its eccentricity. A discrepancy between the expected and observed failure modes of slender walls loaded at low axial load eccentricities is noted in the analysis, whereby slender masonry walls commonly experience compressive material failure when loaded at a low axial load eccentricity, even though slenderness effects are expected to contribute to out-of-plane failure. A potential alternative design procedure template is presented, whereby a wall is first categorized based on its expected failure mode and only then designed either as a wall which is expected to experience slenderness effects (a wall expected to deflect significantly and experience out-of-plane failure) or a wall for which slenderness effects need not be considered because it will likely experience material failure and not deflect much laterally (despite the fact that it would be currently categorized as slender by CSA S304-14 (2014) based on its slenderness ratio).