Hydrogen and oxygen stable isotope analyses of precipitation sampled during Cyclone Mekunu. Durin... more Hydrogen and oxygen stable isotope analyses of precipitation sampled during Cyclone Mekunu. During Cyclone Mekunu rainfall samples were taken at three different stations in southern Oman. The results are expressed in per mil using the conventional delta-notation relative to Vienna Standard Mean Ocean Water (V-SMOW). More or less independent from the instrument, the 1s reproducibility is commonly better than ± 0.2 per mil (d18O) and ± 0.4 per mil (d2H).
Groundwater discharge into the sea occurs along many coastlines around the world in different geo... more Groundwater discharge into the sea occurs along many coastlines around the world in different geological settings and constitutes an important component of global water and matter budget. Estimates of how much water flows into the sea worldwide vary widely and are largely based on onshore studies and hydrological or hydrogeological modeling. In this study, we propose an approach to quantify a deep submarine groundwater outflow from the seafloor by using autonomously measured ocean surface data, i.e., 222Rn as groundwater tracer, in combination with numerical modeling of plume transport. The model and field data suggest that groundwater outflows from a water depth of ∼100 m can reach the sea surface implying that several cubic meters per second of freshwater are discharged into the sea. We postulate an extreme rainfall event 6 months earlier as the likely trigger for the groundwater discharge. This study shows that measurements at the sea surface, which are much easier to conduct than discharge measurements at the seafloor, can be used not only to localize submarine groundwater discharges but, in combination with plume modeling, also to estimate the magnitude of the release flow rate.
Fossil hydrocarbons are indispensables commodities that motorize the global economy, and oil and ... more Fossil hydrocarbons are indispensables commodities that motorize the global economy, and oil and gas are two of those conventional fuels that have been extracted and processed for over a century. During last decade, operators face challenges discovering and developing reservoirs commonly found up to several kilometers underground, for which advanced technologies are developed through different research programs. In order to optimize the current processes to drill and construct oil/gas wells, a large number of mechanical technologies discovered centuries ago by diverse sectors are implemented by well engineers. In petroleum industry, the ancient tube forming manufacturing process founds an application once well engineers intend to produce from reservoirs that cannot be reached unless previous and shallower troublesome formations are isolated. Solid expandable tubular is, for instance, one of those technologies developed to mitigate drilling problems and optimize the well delivery pro...
The ever-increasing energy demand has forced researchers to search for new and cheaper solutions ... more The ever-increasing energy demand has forced researchers to search for new and cheaper solutions for oil and gas production. During construction of new wells or repairing old wells, liner hangers are used to connect two tubular of similar or different diameters. The liner hangers are nothing but an ordinary tubular of API (American Petroleum Institute) standard. The recent development of solid expandable tubular (SETs) has resulted in design and repair of these wells using expandable liner hanger replacing the traditional API tubular. Under high-temperature and high pressure conditions the expandable tubular goes through excessive plastic deformation in order to achieve desired increase in the diameter of tubular after expansion. The goals are to reduce the cost of well delivery, have a sustainable well and avoid premature and unexpected failures during its operational life. The objective of this research is to investigate the operational parameters as well as the structural strengt...
The challenges in exploration and development of unconventional oil and gas resources are enormou... more The challenges in exploration and development of unconventional oil and gas resources are enormous. The complex reservoir characteristics, and oil and gas flow regimes introduce difficulty in predicting the oil and gas in-place, recovery and production profiles, and wells placement, design and completion. Horizontal drilling and completion using centuries-old manufacturing process of tube forming resulted in producing oil and gas from large areas with smaller footprint on the surface. Though expensive but it optimizes the recovery. The in-situ diametral expansion of tubular using a solid mandrel causes permanent deformation in which the system experiences large frictional forces at mandrel/tubular interface resulting in stick-slip phenomenon. It results in varying tubular thickness and diametral eccentricity which causes structural instability in wells leading to premature failure. A finite element model describing the dynamics of stick-slip phenomenon in down-hole tubular expansion...
Journal of Manufacturing Science and Engineering, 2015
In the last decade, traditional tube expansion process has found an innovative application in oil... more In the last decade, traditional tube expansion process has found an innovative application in oil and gas wells drilling and remediation. The ultimate goal is to replace the conventional telescopic wells to monodiameter wells with minimum cost, which is still a distant reality. Further to this, large diameters are needed at terminal depths for enhanced production from a single well while keeping the power required for expansion and related costs to a minimum. Progress has been made to realize slim wells by driving a rigid mandrel of a suitable diameter through the tube either mechanically or hydraulically to attain a desirable expansion ratio. This paper presents a finite element model, which predicts the drawing force for expansion, the stress field in expanded and pre-/postexpanded zones, and the energy required for expansion. Through minimization of energy required for expansion, an optimum mandrel configuration, i.e., shape, size, and angle, was obtained, which can be used to ac...
A model to study the dynamics of a stick-slip phenomenon in expansion of tubes was developed. Dur... more A model to study the dynamics of a stick-slip phenomenon in expansion of tubes was developed. During the permanent deformation process, the system experiences large friction forces at mandrel/tubular interface. This result in an increase of drawing force required for expansion as well as variation in tube thickness along its length. Three different sets of equation; one each for slip phase, stick phase and the transition from stick to slip were derived using equilibrium equations, incompressibility conditions and Karnopp's model. A zero velocity interval was used to define slip, stick and transition phases. The model captured the effect of stick-slip phenomenon on varying thickness reduction along the tube length. The fluctuation in the displacement-time plot clearly indicates the time when the mandrel stuck to the tube. Subsequent slip phase resulted in higher thickness reduction in tube compared to the preceding section. This uneven thickness lowers the structural integrity o...
2019 1st International Conference on Unmanned Vehicle Systems-Oman (UVS), 2019
For years, unmanned vehicle systems have been an integral part of scientific field campaigns and ... more For years, unmanned vehicle systems have been an integral part of scientific field campaigns and commercial applications. To monitor and safely command a diverse fleet of autonomous vehicles, a system is required to integrate and display relevant data of all participating devices. Using web-based applications, such systems become accessible everywhere and at any time from any web-enabled terminal. Furthermore, this will establish exciting new possibilities for operators and scientists to collaborate in real-time. We would like to introduce our web-based application Navigator that aims to provide a new look on monitoring and visualization of cooperative missions of unmanned vehicles. Despite the fact that our software was initially developed to observe marine operations, the backend of our system provides a generic data structure, which can be populated by customizable adapters to interface various vehicle systems and third-party data providers. The web-based frontend of Navigator of...
International Journal of Pressure Vessels and Piping, 2017
The current work presents an investigation of the effects of expansion rate on plasticity and str... more The current work presents an investigation of the effects of expansion rate on plasticity and structural integrity of down-hole solid tubular. Down-hole tubular has proven itself to be a promising technology in oil well applications by providing optimum solutions for many issues. One of the challenges still facing researchers and field engineers in implementing and making down-hole tubular technology cost effective is to conserve structural integrity of tubular. Cold expansion affects mechanical properties and induces residual stresses in tubular, hence reduces its collapse, burst, and fatigue ratings. The knowledge of properties variation is required in correctly predicting life span of tubular under given operational conditions. In present work, cold expansion of tubular under down-hole conditions is experimentally and numerically investigated at different strain rates. Strain rates are varied by changing the velocity of mandrel that is used to expand the tubular. Firstly, different tubular expansion experiments are performed to achieve 16%, 20%, and 24% expansion ratio. Secondly, finite element model of tubular expansion is developed in commercial finite element software ABAQUS. Simulation results are found to be in good agreement with experimental observations. Finally, further simulations are performed to thoroughly analyze the effects of expansion rate on the deformation behavior of tubular. It is found that there is variation in contact pressure at tubular-mandrel interface, effective stress, equivalent plastic strain, and thickness reduction during expansion process. These variations ultimately influence post-expansion properties of tubular particularly collapse and burst strengths, and hence its structural integrity. However, length shortening has marginally affected by expansion rates.
Volume 9: Mechanics of Solids, Structures and Fluids, 2015
The current research work is focused on the development of a combined micromechanical model of tr... more The current research work is focused on the development of a combined micromechanical model of transformation and twinning induced plasticity mechanisms in austenite based high Mn steels. Both mechanisms are combined by incorporating transformation in twinning based crystal plasticity model. Initially, mechanical twinning is incorporated in slip based crystal plasticity model. Afterwards, transformation phenomenon (austenite to martensite) is included in the developed slip and twin based crystal plasticity model. The kinematics of the mechanisms is developed by defining elastic, plastic, and transformation deformation gradients. These deformation gradients are then used to calculate stress tensors. The constitutive equations in terms of integration algorithm are implemented in ABAQUS as a user-defined subroutine. Three dimensional finite element model of single and polycrystal austenite are developed. Single austenite crystal is represented by one finite element while the behavior of polycrystal austenite is estimated through 500 grains. The orientation of each grain is defined through Euler angles. The performance of the model is evaluated through finite element simulations in order to predict the elastic-plastic and transformation behaviors of single and polycrystal austenite under different loading conditions i.e. uniaxial tension and simple shear. The developed model is in good agreement with published literature. In simple shear, prominent difference in stress magnitude is found once twinning mode is incorporated in slip and transformation. This difference has significant magnitude in case of polycrystal austenite. This shows substantial advantage (in terms of strength and formability) of incorporating mechanical twinning along with slip and transformation.
Solid expandable tubular (SET) is an innovative breakthrough in the petroleum industry that aims ... more Solid expandable tubular (SET) is an innovative breakthrough in the petroleum industry that aims to resolve issues associated with deep wells. It consists of in-place plastic deformation of tubular diameter resulting in larger conduit size that allows drilling deeper. However, due to volume constancy, increasing the tubular diameter results in a decrease in its wall-thickness, and hence even an initially thick-walled tubular may convert into thin-walled; especially at high expansion ratios. Extending the frontier of expandable applications require larger expansion percentage and enhanced tubular integrity after expansion, which exceed the capability of current tubular material. Therefore, the current study aims to investigate new alternative materials to be used as tubular for SET technology. Selected AHSS grades including TRIP, TWIP, and DP steels are analyzed numerically using FEM. Experimental validation of the FEM model was carried out using full-scale expandable tubular testing facility available at Sultan Qaboos University (Muscat, Oman). Interesting results in terms of stress, strain, expansion force, burst and collapse pressures, length shortening and wall-thickness reduction were obtained. Bauschinger effect arises at the collapse pressure rating has been considered in the study. It was found that materials with high true uniform elongation (and therefore with large strain hardening capability) are more capable of counteracting strain intensifications caused by plastic deformation, allowing either larger expansion ratio or larger safety margin for the deformation capability of the material at a given expansion ratio.
Hydrogen and oxygen stable isotope analyses of precipitation sampled during Cyclone Mekunu. Durin... more Hydrogen and oxygen stable isotope analyses of precipitation sampled during Cyclone Mekunu. During Cyclone Mekunu rainfall samples were taken at three different stations in southern Oman. The results are expressed in per mil using the conventional delta-notation relative to Vienna Standard Mean Ocean Water (V-SMOW). More or less independent from the instrument, the 1s reproducibility is commonly better than ± 0.2 per mil (d18O) and ± 0.4 per mil (d2H).
Groundwater discharge into the sea occurs along many coastlines around the world in different geo... more Groundwater discharge into the sea occurs along many coastlines around the world in different geological settings and constitutes an important component of global water and matter budget. Estimates of how much water flows into the sea worldwide vary widely and are largely based on onshore studies and hydrological or hydrogeological modeling. In this study, we propose an approach to quantify a deep submarine groundwater outflow from the seafloor by using autonomously measured ocean surface data, i.e., 222Rn as groundwater tracer, in combination with numerical modeling of plume transport. The model and field data suggest that groundwater outflows from a water depth of ∼100 m can reach the sea surface implying that several cubic meters per second of freshwater are discharged into the sea. We postulate an extreme rainfall event 6 months earlier as the likely trigger for the groundwater discharge. This study shows that measurements at the sea surface, which are much easier to conduct than discharge measurements at the seafloor, can be used not only to localize submarine groundwater discharges but, in combination with plume modeling, also to estimate the magnitude of the release flow rate.
Fossil hydrocarbons are indispensables commodities that motorize the global economy, and oil and ... more Fossil hydrocarbons are indispensables commodities that motorize the global economy, and oil and gas are two of those conventional fuels that have been extracted and processed for over a century. During last decade, operators face challenges discovering and developing reservoirs commonly found up to several kilometers underground, for which advanced technologies are developed through different research programs. In order to optimize the current processes to drill and construct oil/gas wells, a large number of mechanical technologies discovered centuries ago by diverse sectors are implemented by well engineers. In petroleum industry, the ancient tube forming manufacturing process founds an application once well engineers intend to produce from reservoirs that cannot be reached unless previous and shallower troublesome formations are isolated. Solid expandable tubular is, for instance, one of those technologies developed to mitigate drilling problems and optimize the well delivery pro...
The ever-increasing energy demand has forced researchers to search for new and cheaper solutions ... more The ever-increasing energy demand has forced researchers to search for new and cheaper solutions for oil and gas production. During construction of new wells or repairing old wells, liner hangers are used to connect two tubular of similar or different diameters. The liner hangers are nothing but an ordinary tubular of API (American Petroleum Institute) standard. The recent development of solid expandable tubular (SETs) has resulted in design and repair of these wells using expandable liner hanger replacing the traditional API tubular. Under high-temperature and high pressure conditions the expandable tubular goes through excessive plastic deformation in order to achieve desired increase in the diameter of tubular after expansion. The goals are to reduce the cost of well delivery, have a sustainable well and avoid premature and unexpected failures during its operational life. The objective of this research is to investigate the operational parameters as well as the structural strengt...
The challenges in exploration and development of unconventional oil and gas resources are enormou... more The challenges in exploration and development of unconventional oil and gas resources are enormous. The complex reservoir characteristics, and oil and gas flow regimes introduce difficulty in predicting the oil and gas in-place, recovery and production profiles, and wells placement, design and completion. Horizontal drilling and completion using centuries-old manufacturing process of tube forming resulted in producing oil and gas from large areas with smaller footprint on the surface. Though expensive but it optimizes the recovery. The in-situ diametral expansion of tubular using a solid mandrel causes permanent deformation in which the system experiences large frictional forces at mandrel/tubular interface resulting in stick-slip phenomenon. It results in varying tubular thickness and diametral eccentricity which causes structural instability in wells leading to premature failure. A finite element model describing the dynamics of stick-slip phenomenon in down-hole tubular expansion...
Journal of Manufacturing Science and Engineering, 2015
In the last decade, traditional tube expansion process has found an innovative application in oil... more In the last decade, traditional tube expansion process has found an innovative application in oil and gas wells drilling and remediation. The ultimate goal is to replace the conventional telescopic wells to monodiameter wells with minimum cost, which is still a distant reality. Further to this, large diameters are needed at terminal depths for enhanced production from a single well while keeping the power required for expansion and related costs to a minimum. Progress has been made to realize slim wells by driving a rigid mandrel of a suitable diameter through the tube either mechanically or hydraulically to attain a desirable expansion ratio. This paper presents a finite element model, which predicts the drawing force for expansion, the stress field in expanded and pre-/postexpanded zones, and the energy required for expansion. Through minimization of energy required for expansion, an optimum mandrel configuration, i.e., shape, size, and angle, was obtained, which can be used to ac...
A model to study the dynamics of a stick-slip phenomenon in expansion of tubes was developed. Dur... more A model to study the dynamics of a stick-slip phenomenon in expansion of tubes was developed. During the permanent deformation process, the system experiences large friction forces at mandrel/tubular interface. This result in an increase of drawing force required for expansion as well as variation in tube thickness along its length. Three different sets of equation; one each for slip phase, stick phase and the transition from stick to slip were derived using equilibrium equations, incompressibility conditions and Karnopp's model. A zero velocity interval was used to define slip, stick and transition phases. The model captured the effect of stick-slip phenomenon on varying thickness reduction along the tube length. The fluctuation in the displacement-time plot clearly indicates the time when the mandrel stuck to the tube. Subsequent slip phase resulted in higher thickness reduction in tube compared to the preceding section. This uneven thickness lowers the structural integrity o...
2019 1st International Conference on Unmanned Vehicle Systems-Oman (UVS), 2019
For years, unmanned vehicle systems have been an integral part of scientific field campaigns and ... more For years, unmanned vehicle systems have been an integral part of scientific field campaigns and commercial applications. To monitor and safely command a diverse fleet of autonomous vehicles, a system is required to integrate and display relevant data of all participating devices. Using web-based applications, such systems become accessible everywhere and at any time from any web-enabled terminal. Furthermore, this will establish exciting new possibilities for operators and scientists to collaborate in real-time. We would like to introduce our web-based application Navigator that aims to provide a new look on monitoring and visualization of cooperative missions of unmanned vehicles. Despite the fact that our software was initially developed to observe marine operations, the backend of our system provides a generic data structure, which can be populated by customizable adapters to interface various vehicle systems and third-party data providers. The web-based frontend of Navigator of...
International Journal of Pressure Vessels and Piping, 2017
The current work presents an investigation of the effects of expansion rate on plasticity and str... more The current work presents an investigation of the effects of expansion rate on plasticity and structural integrity of down-hole solid tubular. Down-hole tubular has proven itself to be a promising technology in oil well applications by providing optimum solutions for many issues. One of the challenges still facing researchers and field engineers in implementing and making down-hole tubular technology cost effective is to conserve structural integrity of tubular. Cold expansion affects mechanical properties and induces residual stresses in tubular, hence reduces its collapse, burst, and fatigue ratings. The knowledge of properties variation is required in correctly predicting life span of tubular under given operational conditions. In present work, cold expansion of tubular under down-hole conditions is experimentally and numerically investigated at different strain rates. Strain rates are varied by changing the velocity of mandrel that is used to expand the tubular. Firstly, different tubular expansion experiments are performed to achieve 16%, 20%, and 24% expansion ratio. Secondly, finite element model of tubular expansion is developed in commercial finite element software ABAQUS. Simulation results are found to be in good agreement with experimental observations. Finally, further simulations are performed to thoroughly analyze the effects of expansion rate on the deformation behavior of tubular. It is found that there is variation in contact pressure at tubular-mandrel interface, effective stress, equivalent plastic strain, and thickness reduction during expansion process. These variations ultimately influence post-expansion properties of tubular particularly collapse and burst strengths, and hence its structural integrity. However, length shortening has marginally affected by expansion rates.
Volume 9: Mechanics of Solids, Structures and Fluids, 2015
The current research work is focused on the development of a combined micromechanical model of tr... more The current research work is focused on the development of a combined micromechanical model of transformation and twinning induced plasticity mechanisms in austenite based high Mn steels. Both mechanisms are combined by incorporating transformation in twinning based crystal plasticity model. Initially, mechanical twinning is incorporated in slip based crystal plasticity model. Afterwards, transformation phenomenon (austenite to martensite) is included in the developed slip and twin based crystal plasticity model. The kinematics of the mechanisms is developed by defining elastic, plastic, and transformation deformation gradients. These deformation gradients are then used to calculate stress tensors. The constitutive equations in terms of integration algorithm are implemented in ABAQUS as a user-defined subroutine. Three dimensional finite element model of single and polycrystal austenite are developed. Single austenite crystal is represented by one finite element while the behavior of polycrystal austenite is estimated through 500 grains. The orientation of each grain is defined through Euler angles. The performance of the model is evaluated through finite element simulations in order to predict the elastic-plastic and transformation behaviors of single and polycrystal austenite under different loading conditions i.e. uniaxial tension and simple shear. The developed model is in good agreement with published literature. In simple shear, prominent difference in stress magnitude is found once twinning mode is incorporated in slip and transformation. This difference has significant magnitude in case of polycrystal austenite. This shows substantial advantage (in terms of strength and formability) of incorporating mechanical twinning along with slip and transformation.
Solid expandable tubular (SET) is an innovative breakthrough in the petroleum industry that aims ... more Solid expandable tubular (SET) is an innovative breakthrough in the petroleum industry that aims to resolve issues associated with deep wells. It consists of in-place plastic deformation of tubular diameter resulting in larger conduit size that allows drilling deeper. However, due to volume constancy, increasing the tubular diameter results in a decrease in its wall-thickness, and hence even an initially thick-walled tubular may convert into thin-walled; especially at high expansion ratios. Extending the frontier of expandable applications require larger expansion percentage and enhanced tubular integrity after expansion, which exceed the capability of current tubular material. Therefore, the current study aims to investigate new alternative materials to be used as tubular for SET technology. Selected AHSS grades including TRIP, TWIP, and DP steels are analyzed numerically using FEM. Experimental validation of the FEM model was carried out using full-scale expandable tubular testing facility available at Sultan Qaboos University (Muscat, Oman). Interesting results in terms of stress, strain, expansion force, burst and collapse pressures, length shortening and wall-thickness reduction were obtained. Bauschinger effect arises at the collapse pressure rating has been considered in the study. It was found that materials with high true uniform elongation (and therefore with large strain hardening capability) are more capable of counteracting strain intensifications caused by plastic deformation, allowing either larger expansion ratio or larger safety margin for the deformation capability of the material at a given expansion ratio.
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Papers by Omar Al-Abri