Daniel Quesada - Academia.edu (original) (raw)
Papers by Daniel Quesada
HAL (Le Centre pour la Communication Scientifique Directe), May 21, 2007
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Stability of a leakage pathway in a cemented annulus
Energy Procedia, 2011
The risk minimization of carbon dioxide (CO 2) storage relies to some extent on well integrity as... more The risk minimization of carbon dioxide (CO 2) storage relies to some extent on well integrity assurance. While chemical reactions between the constitutive materials of the wellbore-such as cement-and stored CO 2 do not jeopardize the efficiency of a defect-free cement sheath, the reactive flow through an existing pathway in a cemented annulus may alter its initial properties, and thus change the associated risk. On one hand, the cement will react with the CO 2 rich fluid, and be leached away by the leaking flow. On another hand, under specific conditions, the released minerals can re-precipitate downstream and clog the pathway. The evolution of a CO 2 leak through a pre-existing leak path in the cement sheath is examined theoretically and numerically. A numerical model of the flow has been built, that takes into account the particular physics and geometry of the problem. The governing equations are investigated in order to identify the driving mechanisms and define the dimensionless groups that rule the process, leading to a reduction in the dimension of the parameters space. We use this analysis to predict the domain of stability of the defect by extracting a general criterion corresponding to the clogging conditions.
Energy Procedia, 2011
Carbon dioxide (CO 2) geological storage relies on safe, long-term injection of large quantities ... more Carbon dioxide (CO 2) geological storage relies on safe, long-term injection of large quantities of CO 2 in underground porous rocks. Wells, whether they are the conduit of the pumped fluid or are exposed to CO 2 in the storage reservoir (observation and old wells) are man-made disturbances to the geological storage complex, and are thus viewed by some as a possible risk factor to the containment of the injected CO 2. Wells are composite structures, with an inner steel pipe separated from the borehole rock wall by a thin cement sheath (~2 cm) that prevents vertical fluid migration. Both carbon steel and cement react in the presence of CO 2 , although evidence from production of CO 2-rich fluids in the oil and gas industry and from lab experiments suggests that competent, defect-free cement offers an effective barrier to CO 2 migration and leaks.
Energy Procedia, 2011
The concept of CO 2 storage relies on the long-term sealing properties of both the geological tra... more The concept of CO 2 storage relies on the long-term sealing properties of both the geological trap and the wells needed to inject and monitor CO 2. Well integrity, a classical topic in the oil and gas industry, is thus critical for the performance of any CO 2 storage complex in terms of containment. Thanks to the very low permeability of cement (typically less than 0.1 mDarcy); a properly cemented well ensures hydraulic isolation between reservoirs layers and shallow aquifers. Moreover, such low matrix permeability limits the cement / CO 2 interactions over the active period of a storage complex (of the order of 100 years) to a few meters. Leaks from a cased and cemented well, if any, are known to occur only through defects: mud-channel (in case of poor cement placement), cracks within cement and more importantly micro-annulus at the casing / cement or / and cement / formation interfaces. This last category of defects can lead to substantial leakage rate. Its importance has been recognized by the oil and gas industry since the 1960's leading to the study of cement " bonding" properties. In the scope of CO 2 storage, the understanding, modeling and monitoring of the occurrence of micro-annulus becomes of prime importance. We analyze the complete loading history of a cemented completion from cement placement to routine well operations. Further to classical failure type assessment used in the oil and gas industry (i.e. fail / no fail, good cement / bad cement), we aim at quantifying the vertical extent, azimuthal coverage and width of the created defects to adequately transform failure types into leakage pathways. Such a prediction of connected defects / leakage pathways along a cemented well imposes to consistently integrate the effects of lithology, geomechanics, cement placement (fluid loss, hydration), completion design and knowledge of pressure and thermal variation during the life of the well. The modeling of such a problem can be made tractable by recognizing the intrinsic hierarchy of lengthscales of a cemented well (i.e. the cement annulus is much thinner than the well dimension). The original three-dimensional problem is reduced to a much simpler two-dimensional one, which in turn can even be further reduced to a one-dimensional configuration in a lot of practical cases. Typical cases of interface debonding due to well de-pressurization and thermal cooling taking place after cement placement are carefully analyzed. Furthermore, we specially focus on injectors. Despite the use of all current best practices during well construction, the injection in itself can lead to the propagation of a debonding crack between cement and casing or cement and formation due to the high pressure generated at the perforations level. Such a problem has already been reported in hydraulic fracturing operations, and is a reasonable explanation of observed well leaks for injectors. A consistent model predicting the initiation and propagation of interface debonding during injection operations is then compared to carefully designed laboratory experiments. Such experiments also confirm that the azimuthal coverage of the interface debonding is only partial (i.e. less than 360 o), an observation consistent with cement evaluation logs acquired on CO 2 injectors. Finally, best practices to achieve and
All Days, 2010
Well integrity is one of the major concerns when assessing the containment of a geological CO2 st... more Well integrity is one of the major concerns when assessing the containment of a geological CO2 storage. Whereas defect-free cement sheaths provide reliable barriers that prevent vertical migration or leakage of the stored CO2, significant leakage can occur if pathways appear in the cement seal: the stored fluid can flow through and alter their initial properties. A simulator has been built to numerically investigate the leakage rate of CO2 rich fluid through a pathway along a cemented annulus. Careful analysis of the physics and characteristic dimensions of the phenomena allows coupling of the flow, the mechanics of any defect and the chemical reactions that take place in the materials (fluid and cement). Results of the simulation, besides predicting the instantaneous flow rate and hydraulic conductivity of the defect, show different mechanisms of flow rates variation with time: in particular, coupling between flow along the defect and chemical reaction between cement and CO2 can le...
Energy Procedia, 2011
The risk minimization of carbon dioxide (CO 2 ) storage relies to some extent on well integrity a... more The risk minimization of carbon dioxide (CO 2 ) storage relies to some extent on well integrity assurance. While chemical reactions between the constitutive materials of the wellboresuch as cementand stored CO 2 do not jeopardize the efficiency of a defect-free cement ...
International Petroleum Technology Conference, 2015
International Journal of Greenhouse Gas Control, 2013
The integrity of the wellbore completion under injection conditions is vital for the effective, l... more The integrity of the wellbore completion under injection conditions is vital for the effective, long term storage of carbon dioxide. Here we experimentally demonstrate and mathematically model fluid-driven debonding of the wellbore annulus in order to provide a fundamental basis for well design. We show that self-limiting versus self-sustaining propagation of the annular debonding are distinguished by the sign of a fluid buoyancy parameter that involves a non-trivial relationship between the hydrostatic pressure variation of the fluid with depth and the clamping stress provided by the internally-pressurized casing/cement system. The theory also gives a series of scaling relationships that can be used to predict the rate of growth of the debonding and the fluid flux through the annulus for various growth regimes. The experiments confirm the theoretical predictions of debonding growth rate for the limiting case of zero-buoyancy. We also observe azimuthal debonding extending around 1/2 to 3/4 of the well annulus in the experiments, which is shown to be consistent with physical insights that can be derived from the theoretical model. We conclude that the clamping stress on the well annulus is a critical quantity for hydraulic isolation of the well, and therefore appropriate design of the casing/cement system relative to the intended injection conditions is necessary for the integrity of CO 2 injection wells.
International Journal of Rock Mechanics and Mining Sciences, Feb 1, 2009
Multilayer jointing in tight oil and gas reservoirs is a useful indicator for the prediction of f... more Multilayer jointing in tight oil and gas reservoirs is a useful indicator for the prediction of fluid mobility. Since pore pressure balances the principal minor horizontal stress at depth, joint nucleations, considered as sub-vertical, are mainly driven by the overburden pressure. We demonstrate, with a mixed criterion combining necessary conditions of stress and energy, how heterogeneity such as an interbed
Engineering Fracture Mechanics, Oct 1, 2007
ABSTRACT Crack initiation at corners, V-notches and other situations such as interfaces breaking ... more ABSTRACT Crack initiation at corners, V-notches and other situations such as interfaces breaking a free surface (delamination initiation) cannot be correctly predicted by the usual brittle fracture criteria (either Griffith or maximum stress). They give contradictory results and neither one nor the other agrees with the experiments. An additional characteristic length is required to define a satisfying criterion giving rise to the so-called “Finite fracture mechanics”. The crack is supposed to jump this length which depends both on the material properties and the local geometry of the structure; it is not a material parameter. In most cases this crack increment is small. The size effect arises with the interaction between the crack increment and another length characterising a microstructure such as a pore diameter, a notch root radius or an interface layer thickness. The remote load at failure depends on the actual value of this microstructure parameter whereas it was not expected in all cases. Assuming that the two interacting lengths remain small compared to the size of the global structure, an asymptotic procedure allows bringing into evidence the change in the apparent resistance of the structure due to this phenomenon. Results are compared with experiments in various domains: polymers, ceramics and rocks.
Comprendre la formation et la disposition des fractures naturelles dans les réservoirs peu poreux... more Comprendre la formation et la disposition des fractures naturelles dans les réservoirs peu poreux est vital en production pétrolière. Deux types d'hétérogénéités susceptibles de faciliter l'amorçage des fractures dans un état de contraintes lithostatiques réprésentatif (profondeur d'enfouissement et tectonique apparaissant comme facteurs essentiels) sont étudiés sur un plan théorique et numérique. Les géométries "cavité circulaire" et "alternance banc/interbanc", en condition de faible confinement effectif, permettent de discuter l'effet de taille. Cela illustre notamment les différences de comportement entre les échantillons de laboratoire et la roche à l'échelle du massif. Les mécanismes de rupture étudiés sont l'amorçage aux pôles de la cavité et la propagation d'une fracture avec saut d'interbanc. Le modèle prédit effectivement la longueur amorcée.
SPE International Conference on CO2 Capture, Storage, and Utilization, 2010
Copyright 2010, Society of Petroleum Engineers This paper was prepared for presentation at the SP... more Copyright 2010, Society of Petroleum Engineers This paper was prepared for presentation at the SPE International Conference on CO2 Capture, Storage, and Utilization held in New Orleans, Louisiana, USA, 1012 November 2010. This paper was selected for ...
Energy Procedia, 2011
The risk minimization of carbon dioxide (CO 2 ) storage relies to some extent on well integrity a... more The risk minimization of carbon dioxide (CO 2 ) storage relies to some extent on well integrity assurance. While chemical reactions between the constitutive materials of the wellboresuch as cementand stored CO 2 do not jeopardize the efficiency of a defect-free cement ...
Important contributors to reservoir permeability are fracture systems common in low porosity rese... more Important contributors to reservoir permeability are fracture systems common in low porosity reservoirs. Although the conditions of fracturing in reservoirs on anticlines, in tectonically deformed areas, are relatively well identified, the formation of regional fractures in flat-lying reservoirs is still unclear. Such regional fractures have a great economic significance and are known to form at depth as a result of
SPE Annual Technical Conference and Exhibition, 2014
Energy Procedia, 2011
The concept of CO 2 storage relies on the long-term sealing properties of both the geological tra... more The concept of CO 2 storage relies on the long-term sealing properties of both the geological trap and the wells needed to inject and monitor CO 2 . Well integrity, a classical topic in the oil and gas industry, is thus critical for the performance of any CO 2 storage complex in terms of containment. Thanks to the very low permeability of cement (typically less than 0.1 mDarcy); a properly cemented well ensures hydraulic isolation between reservoirs layers and shallow aquifers. Moreover, such low matrix permeability limits the cement / CO 2 interactions over the active period of a storage complex (of the order of 100 years) to a few meters. Leaks from a cased and cemented well, if any, are known to occur only through defects: mud-channel (in case of poor cement placement), cracks within cement and more importantly micro-annulus at the casing / cement or / and cement / formation interfaces. This last category of defects can lead to substantial leakage rate. Its importance has been recognized by the oil and gas industry since the 1960's leading to the study of cement " bonding" properties. In the scope of CO 2 storage, the understanding, modeling and monitoring of the occurrence of micro-annulus becomes of prime importance. We analyze the complete loading history of a cemented completion from cement placement to routine well operations. Further to classical failure type assessment used in the oil and gas industry (i.e. fail / no fail, good cement / bad cement), we aim at quantifying the vertical extent, azimuthal coverage and width of the created defects to adequately transform failure types into leakage pathways. Such a prediction of connected defects / leakage pathways along a cemented well imposes to consistently integrate the effects of lithology, geomechanics, cement placement (fluid loss, hydration), completion design and knowledge of pressure and thermal variation during the life of the well. The modeling of such a problem can be made tractable by recognizing the intrinsic hierarchy of lengthscales of a cemented well (i.e. the cement annulus is much thinner than the well dimension). The original three-dimensional problem is reduced to a much simpler two-dimensional one, which in turn can even be further reduced to a one-dimensional configuration in a lot of practical cases. Typical cases of interface debonding due to well de-pressurization and thermal cooling taking place after cement placement are carefully analyzed. Furthermore, we specially focus on injectors. Despite the use of all current best practices during well construction, the injection in itself can lead to the propagation of a debonding crack between cement and casing or cement and formation due to the high pressure generated at the perforations level. Such a problem has already been reported in hydraulic fracturing operations, and is a reasonable explanation of observed well leaks for injectors. A consistent model predicting the initiation and propagation of interface debonding during injection operations is then compared to carefully designed laboratory experiments. Such experiments also confirm that the azimuthal coverage of the interface debonding is only partial (i.e. less than 360 o ), an observation consistent with cement evaluation logs acquired on CO 2 injectors. Finally, best practices to achieve and
International Journal of Rock Mechanics and Mining Sciences, 2009
Multilayer jointing in tight oil and gas reservoirs is a useful indicator for the prediction of f... more Multilayer jointing in tight oil and gas reservoirs is a useful indicator for the prediction of fluid mobility. Since pore pressure balances the principal minor horizontal stress at depth, joint nucleations, considered as sub-vertical, are mainly driven by the overburden pressure. We demonstrate, with a mixed criterion combining necessary conditions of stress and energy, how heterogeneity such as an interbed
HAL (Le Centre pour la Communication Scientifique Directe), May 21, 2007
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
Stability of a leakage pathway in a cemented annulus
Energy Procedia, 2011
The risk minimization of carbon dioxide (CO 2) storage relies to some extent on well integrity as... more The risk minimization of carbon dioxide (CO 2) storage relies to some extent on well integrity assurance. While chemical reactions between the constitutive materials of the wellbore-such as cement-and stored CO 2 do not jeopardize the efficiency of a defect-free cement sheath, the reactive flow through an existing pathway in a cemented annulus may alter its initial properties, and thus change the associated risk. On one hand, the cement will react with the CO 2 rich fluid, and be leached away by the leaking flow. On another hand, under specific conditions, the released minerals can re-precipitate downstream and clog the pathway. The evolution of a CO 2 leak through a pre-existing leak path in the cement sheath is examined theoretically and numerically. A numerical model of the flow has been built, that takes into account the particular physics and geometry of the problem. The governing equations are investigated in order to identify the driving mechanisms and define the dimensionless groups that rule the process, leading to a reduction in the dimension of the parameters space. We use this analysis to predict the domain of stability of the defect by extracting a general criterion corresponding to the clogging conditions.
Energy Procedia, 2011
Carbon dioxide (CO 2) geological storage relies on safe, long-term injection of large quantities ... more Carbon dioxide (CO 2) geological storage relies on safe, long-term injection of large quantities of CO 2 in underground porous rocks. Wells, whether they are the conduit of the pumped fluid or are exposed to CO 2 in the storage reservoir (observation and old wells) are man-made disturbances to the geological storage complex, and are thus viewed by some as a possible risk factor to the containment of the injected CO 2. Wells are composite structures, with an inner steel pipe separated from the borehole rock wall by a thin cement sheath (~2 cm) that prevents vertical fluid migration. Both carbon steel and cement react in the presence of CO 2 , although evidence from production of CO 2-rich fluids in the oil and gas industry and from lab experiments suggests that competent, defect-free cement offers an effective barrier to CO 2 migration and leaks.
Energy Procedia, 2011
The concept of CO 2 storage relies on the long-term sealing properties of both the geological tra... more The concept of CO 2 storage relies on the long-term sealing properties of both the geological trap and the wells needed to inject and monitor CO 2. Well integrity, a classical topic in the oil and gas industry, is thus critical for the performance of any CO 2 storage complex in terms of containment. Thanks to the very low permeability of cement (typically less than 0.1 mDarcy); a properly cemented well ensures hydraulic isolation between reservoirs layers and shallow aquifers. Moreover, such low matrix permeability limits the cement / CO 2 interactions over the active period of a storage complex (of the order of 100 years) to a few meters. Leaks from a cased and cemented well, if any, are known to occur only through defects: mud-channel (in case of poor cement placement), cracks within cement and more importantly micro-annulus at the casing / cement or / and cement / formation interfaces. This last category of defects can lead to substantial leakage rate. Its importance has been recognized by the oil and gas industry since the 1960's leading to the study of cement " bonding" properties. In the scope of CO 2 storage, the understanding, modeling and monitoring of the occurrence of micro-annulus becomes of prime importance. We analyze the complete loading history of a cemented completion from cement placement to routine well operations. Further to classical failure type assessment used in the oil and gas industry (i.e. fail / no fail, good cement / bad cement), we aim at quantifying the vertical extent, azimuthal coverage and width of the created defects to adequately transform failure types into leakage pathways. Such a prediction of connected defects / leakage pathways along a cemented well imposes to consistently integrate the effects of lithology, geomechanics, cement placement (fluid loss, hydration), completion design and knowledge of pressure and thermal variation during the life of the well. The modeling of such a problem can be made tractable by recognizing the intrinsic hierarchy of lengthscales of a cemented well (i.e. the cement annulus is much thinner than the well dimension). The original three-dimensional problem is reduced to a much simpler two-dimensional one, which in turn can even be further reduced to a one-dimensional configuration in a lot of practical cases. Typical cases of interface debonding due to well de-pressurization and thermal cooling taking place after cement placement are carefully analyzed. Furthermore, we specially focus on injectors. Despite the use of all current best practices during well construction, the injection in itself can lead to the propagation of a debonding crack between cement and casing or cement and formation due to the high pressure generated at the perforations level. Such a problem has already been reported in hydraulic fracturing operations, and is a reasonable explanation of observed well leaks for injectors. A consistent model predicting the initiation and propagation of interface debonding during injection operations is then compared to carefully designed laboratory experiments. Such experiments also confirm that the azimuthal coverage of the interface debonding is only partial (i.e. less than 360 o), an observation consistent with cement evaluation logs acquired on CO 2 injectors. Finally, best practices to achieve and
All Days, 2010
Well integrity is one of the major concerns when assessing the containment of a geological CO2 st... more Well integrity is one of the major concerns when assessing the containment of a geological CO2 storage. Whereas defect-free cement sheaths provide reliable barriers that prevent vertical migration or leakage of the stored CO2, significant leakage can occur if pathways appear in the cement seal: the stored fluid can flow through and alter their initial properties. A simulator has been built to numerically investigate the leakage rate of CO2 rich fluid through a pathway along a cemented annulus. Careful analysis of the physics and characteristic dimensions of the phenomena allows coupling of the flow, the mechanics of any defect and the chemical reactions that take place in the materials (fluid and cement). Results of the simulation, besides predicting the instantaneous flow rate and hydraulic conductivity of the defect, show different mechanisms of flow rates variation with time: in particular, coupling between flow along the defect and chemical reaction between cement and CO2 can le...
Energy Procedia, 2011
The risk minimization of carbon dioxide (CO 2 ) storage relies to some extent on well integrity a... more The risk minimization of carbon dioxide (CO 2 ) storage relies to some extent on well integrity assurance. While chemical reactions between the constitutive materials of the wellboresuch as cementand stored CO 2 do not jeopardize the efficiency of a defect-free cement ...
International Petroleum Technology Conference, 2015
International Journal of Greenhouse Gas Control, 2013
The integrity of the wellbore completion under injection conditions is vital for the effective, l... more The integrity of the wellbore completion under injection conditions is vital for the effective, long term storage of carbon dioxide. Here we experimentally demonstrate and mathematically model fluid-driven debonding of the wellbore annulus in order to provide a fundamental basis for well design. We show that self-limiting versus self-sustaining propagation of the annular debonding are distinguished by the sign of a fluid buoyancy parameter that involves a non-trivial relationship between the hydrostatic pressure variation of the fluid with depth and the clamping stress provided by the internally-pressurized casing/cement system. The theory also gives a series of scaling relationships that can be used to predict the rate of growth of the debonding and the fluid flux through the annulus for various growth regimes. The experiments confirm the theoretical predictions of debonding growth rate for the limiting case of zero-buoyancy. We also observe azimuthal debonding extending around 1/2 to 3/4 of the well annulus in the experiments, which is shown to be consistent with physical insights that can be derived from the theoretical model. We conclude that the clamping stress on the well annulus is a critical quantity for hydraulic isolation of the well, and therefore appropriate design of the casing/cement system relative to the intended injection conditions is necessary for the integrity of CO 2 injection wells.
International Journal of Rock Mechanics and Mining Sciences, Feb 1, 2009
Multilayer jointing in tight oil and gas reservoirs is a useful indicator for the prediction of f... more Multilayer jointing in tight oil and gas reservoirs is a useful indicator for the prediction of fluid mobility. Since pore pressure balances the principal minor horizontal stress at depth, joint nucleations, considered as sub-vertical, are mainly driven by the overburden pressure. We demonstrate, with a mixed criterion combining necessary conditions of stress and energy, how heterogeneity such as an interbed
Engineering Fracture Mechanics, Oct 1, 2007
ABSTRACT Crack initiation at corners, V-notches and other situations such as interfaces breaking ... more ABSTRACT Crack initiation at corners, V-notches and other situations such as interfaces breaking a free surface (delamination initiation) cannot be correctly predicted by the usual brittle fracture criteria (either Griffith or maximum stress). They give contradictory results and neither one nor the other agrees with the experiments. An additional characteristic length is required to define a satisfying criterion giving rise to the so-called “Finite fracture mechanics”. The crack is supposed to jump this length which depends both on the material properties and the local geometry of the structure; it is not a material parameter. In most cases this crack increment is small. The size effect arises with the interaction between the crack increment and another length characterising a microstructure such as a pore diameter, a notch root radius or an interface layer thickness. The remote load at failure depends on the actual value of this microstructure parameter whereas it was not expected in all cases. Assuming that the two interacting lengths remain small compared to the size of the global structure, an asymptotic procedure allows bringing into evidence the change in the apparent resistance of the structure due to this phenomenon. Results are compared with experiments in various domains: polymers, ceramics and rocks.
Comprendre la formation et la disposition des fractures naturelles dans les réservoirs peu poreux... more Comprendre la formation et la disposition des fractures naturelles dans les réservoirs peu poreux est vital en production pétrolière. Deux types d'hétérogénéités susceptibles de faciliter l'amorçage des fractures dans un état de contraintes lithostatiques réprésentatif (profondeur d'enfouissement et tectonique apparaissant comme facteurs essentiels) sont étudiés sur un plan théorique et numérique. Les géométries "cavité circulaire" et "alternance banc/interbanc", en condition de faible confinement effectif, permettent de discuter l'effet de taille. Cela illustre notamment les différences de comportement entre les échantillons de laboratoire et la roche à l'échelle du massif. Les mécanismes de rupture étudiés sont l'amorçage aux pôles de la cavité et la propagation d'une fracture avec saut d'interbanc. Le modèle prédit effectivement la longueur amorcée.
SPE International Conference on CO2 Capture, Storage, and Utilization, 2010
Copyright 2010, Society of Petroleum Engineers This paper was prepared for presentation at the SP... more Copyright 2010, Society of Petroleum Engineers This paper was prepared for presentation at the SPE International Conference on CO2 Capture, Storage, and Utilization held in New Orleans, Louisiana, USA, 1012 November 2010. This paper was selected for ...
Energy Procedia, 2011
The risk minimization of carbon dioxide (CO 2 ) storage relies to some extent on well integrity a... more The risk minimization of carbon dioxide (CO 2 ) storage relies to some extent on well integrity assurance. While chemical reactions between the constitutive materials of the wellboresuch as cementand stored CO 2 do not jeopardize the efficiency of a defect-free cement ...
Important contributors to reservoir permeability are fracture systems common in low porosity rese... more Important contributors to reservoir permeability are fracture systems common in low porosity reservoirs. Although the conditions of fracturing in reservoirs on anticlines, in tectonically deformed areas, are relatively well identified, the formation of regional fractures in flat-lying reservoirs is still unclear. Such regional fractures have a great economic significance and are known to form at depth as a result of
SPE Annual Technical Conference and Exhibition, 2014
Energy Procedia, 2011
The concept of CO 2 storage relies on the long-term sealing properties of both the geological tra... more The concept of CO 2 storage relies on the long-term sealing properties of both the geological trap and the wells needed to inject and monitor CO 2 . Well integrity, a classical topic in the oil and gas industry, is thus critical for the performance of any CO 2 storage complex in terms of containment. Thanks to the very low permeability of cement (typically less than 0.1 mDarcy); a properly cemented well ensures hydraulic isolation between reservoirs layers and shallow aquifers. Moreover, such low matrix permeability limits the cement / CO 2 interactions over the active period of a storage complex (of the order of 100 years) to a few meters. Leaks from a cased and cemented well, if any, are known to occur only through defects: mud-channel (in case of poor cement placement), cracks within cement and more importantly micro-annulus at the casing / cement or / and cement / formation interfaces. This last category of defects can lead to substantial leakage rate. Its importance has been recognized by the oil and gas industry since the 1960's leading to the study of cement " bonding" properties. In the scope of CO 2 storage, the understanding, modeling and monitoring of the occurrence of micro-annulus becomes of prime importance. We analyze the complete loading history of a cemented completion from cement placement to routine well operations. Further to classical failure type assessment used in the oil and gas industry (i.e. fail / no fail, good cement / bad cement), we aim at quantifying the vertical extent, azimuthal coverage and width of the created defects to adequately transform failure types into leakage pathways. Such a prediction of connected defects / leakage pathways along a cemented well imposes to consistently integrate the effects of lithology, geomechanics, cement placement (fluid loss, hydration), completion design and knowledge of pressure and thermal variation during the life of the well. The modeling of such a problem can be made tractable by recognizing the intrinsic hierarchy of lengthscales of a cemented well (i.e. the cement annulus is much thinner than the well dimension). The original three-dimensional problem is reduced to a much simpler two-dimensional one, which in turn can even be further reduced to a one-dimensional configuration in a lot of practical cases. Typical cases of interface debonding due to well de-pressurization and thermal cooling taking place after cement placement are carefully analyzed. Furthermore, we specially focus on injectors. Despite the use of all current best practices during well construction, the injection in itself can lead to the propagation of a debonding crack between cement and casing or cement and formation due to the high pressure generated at the perforations level. Such a problem has already been reported in hydraulic fracturing operations, and is a reasonable explanation of observed well leaks for injectors. A consistent model predicting the initiation and propagation of interface debonding during injection operations is then compared to carefully designed laboratory experiments. Such experiments also confirm that the azimuthal coverage of the interface debonding is only partial (i.e. less than 360 o ), an observation consistent with cement evaluation logs acquired on CO 2 injectors. Finally, best practices to achieve and
International Journal of Rock Mechanics and Mining Sciences, 2009
Multilayer jointing in tight oil and gas reservoirs is a useful indicator for the prediction of f... more Multilayer jointing in tight oil and gas reservoirs is a useful indicator for the prediction of fluid mobility. Since pore pressure balances the principal minor horizontal stress at depth, joint nucleations, considered as sub-vertical, are mainly driven by the overburden pressure. We demonstrate, with a mixed criterion combining necessary conditions of stress and energy, how heterogeneity such as an interbed