This study focuses on the origin of prograding shelfbreaks on passive margins, using as examples ... more This study focuses on the origin of prograding shelfbreaks on passive margins, using as examples selected seismic sections recorded on Iberian Atlantic and Western Mediterranean margins. Five main factors appear to control shelf progradation: (1) the amount and nature of sediment contributed to the outer shelf; (2) the equilibrium depth H at which sedimentary particles come to rest, a factor depending on grain-size distribution and specific hydrodynamic conditions at the depositional site (according to the models presented herein, H is the shelfbreak depth); (3) the morphology of the margin, i.e. the shelfbreak is significantly prograding only where the shelf forms on a slightly inclined slope or a marginal plateau; (4) the geological activity of the margin, i.e. prograding shelves have a sigmoid configuration on young subsiding margins, and an oblique configuration on mature, slowly subsiding margins; (5) the eustatic sealevel changes, i.e. the shelfbreak is eroded during periods of low sealevel and is built-up and progrades during periods of high sealevel. In sum, the prograding outer edge of shelves provides a fairly reliable record of Quaternary sealevel changes and of the geological evolution of margins, of which they are an integral part.
Our attraction to the mineral world is stimulated by the wide range of chromatic compositions fou... more Our attraction to the mineral world is stimulated by the wide range of chromatic compositions found in the stones. Tuscany holds the most emblematic of these curiosities. Paesina stones , with their famous ruin sceneries ), have decorated many cabinets of curiosity since the 16th century.Less known, Verde d'Arno stones, with their abstract triangular compositions , are highly prized for their delicate shades of green. But the most original of these pictural stones were only discovered in 1988, in the form of pebbles ("Ciottoli" in Italian), on the beaches of Tuscany. These are the "Giottoli", as baptized by Roberto Mari, because they are pebbles painted by nature in the colors of Giotto , the Italian master of the early Renaissance. They exhibit a large chromatic diversity related to the strong alteration due to the high magmatic and hydrothermal activities in this region of thinned continental crust.
A serpentinite diapir made of altered plagioclase-bearing lherzolites, has been emplaced west of ... more A serpentinite diapir made of altered plagioclase-bearing lherzolites, has been emplaced west of the Galicia Bank at the boundary between oceanic crust and the probable thinned continental crust, that underlies the Iberian margin. ... 2J.R. Vanney, JL Auxietre and JP Dunand, ...
Extensional Tectonics and Stratigraphy of the North Atlantic Margins, 1989
A multichannel seismic survey of the Tagus abyssal plain defines the extent of oceanic crust and ... more A multichannel seismic survey of the Tagus abyssal plain defines the extent of oceanic crust and the continent-ocean boundary. This boundary is marked by landward-dipping reflectors. The oceanic domain is divided into two parts: a deep eastern basin, where an abandoned earliest Cretaceous spreading center is inferred, and a shallower western basin formed after a ridge jump. This latter oceanic domain may have a western complement in the Newfoundland basin.
Methode d'acquisition et de traitement de donnees sismiques, utilisee dans le cadre d'une... more Methode d'acquisition et de traitement de donnees sismiques, utilisee dans le cadre d'une surveillance repetitive du deplacement des fluides impregnant un reservoir (1) situe en profondeur dans le sous-sol. Selon l'invention, elle comporte les etapes consistant a amenager en chaque point d'une grille predeterminee en surface, un trou (100) vertical et de faible profondeur dans le sous-sol au-dessus du reservoir et traversant la zone d'alteration superficielle (2) ; positionner verticalement dans chaque trou des recepteurs (101,102,103,104,105,106,107,108) fixes, destines a etre connectes separement a un enregistreur (300) place en surface ; emettre a proximite de la verticale de chaque trou des ondes sismiques dans le sous-sol au moyen d'une source (200) placee en surface ; enregistrer pour chaque trou, au moyen des recepteurs, les ondes sismiques incidentes directes (10) et les ondes sismiques reflechies (20) aux interfaces des couches profondes, chaque rece...
In 1986 the french submersible Nautile dived to 3.500 m-5.500 m at Galicia Margin in the area dri... more In 1986 the french submersible Nautile dived to 3.500 m-5.500 m at Galicia Margin in the area drilled by the JOIDES Resolution O-V (CDP, Leg 103). Three different kinds of seafloor were investigated: a) the Galicia passive margin (basement and sediments); b) a basa/tic seafloor (probably a piece of Cretaceous oceanic crust of the Biscay Bay; c) a 100 km long belt of serpentinized peridotites (ultramafic seafloor) extended between the oceanic and the thinned continental crust
Dredge samples of Upper Jurassic-lowest Cretaceous limestones were recovered from western Galicia... more Dredge samples of Upper Jurassic-lowest Cretaceous limestones were recovered from western Galicia margin. Lime-stones include benthic and/or planktonic assemblages, which were deposited in environments ranging from inner to outer shelf or upper slope.
Land recording systems are composed of many receiver-points connected by cable to a central unit ... more Land recording systems are composed of many receiver-points connected by cable to a central unit for synchronization, real-time transmission and quality control of the seismic data. With the growing amount of channels in use and the exploration of frontier areas cable systems may become less productive. In difficult access or environmentally sensitive areas, they are complemented or replaced by cableless systems (D. Mougenot, First Break, February 2010). Such systems are not new, but they used to be expensive and quite difficult to synchronize using conventional radio antennas. Since 2005, with the availability of low cost low power consumption GPS chips used for synchronization, cableless systems have become more affordable and reliable. Today, they offer a cost effective alternative to the cable systems in some areas. In the Americas, the use of cableless systems is growing very fast while in other countries like China, India, Russia and the Middle East their use is still in infan...
In what is almost a chicken and egg analogy, someone has to commit first to move this technology ... more In what is almost a chicken and egg analogy, someone has to commit first to move this technology into widespread marine use, and eventually into even deeper waters. Equipment suppliers and service providers have shown their faith in the technology, as evidenced by multi-client ocean bottom cable (OBC) surveys and the recent introduction of 2,000-m (6,500-ft) rated OBC systems. For its part, BP has just contracted Seabed Geophysical AS, a Norwegian seismic contractor that specializes in 4C systems, to develop, build and test a prototype multicomponent system. Although this occurred too close to press time to cover and details may be too tentative and proprietary in any case the system will be a 4C, 250-node autonomous deployment designed to operate in 3,000-m (9,850-ft) waters.
In the Chinese domestic market, the main seismic contractors have been early adopters of MEMS-bas... more In the Chinese domestic market, the main seismic contractors have been early adopters of MEMS-based accelerometers. With the active support of the national oil companies they recorded single-sensor 3D as early as 2004. Today, the many surveys acquired with these 1C or 3C digital sensors cover a full fold area of about 2000 km2, mainly in the northern and central parts of China. All these surveys were shot with explosives (up to 10kg). The receiver interval was from 10 to 50m, and spreads requiring up to 11,520 RP’s were used. The resulting trace density ranged from 105,000 traces/km2 for the early surveys up to 7.2 million traces/km2 for the most recent ones. Compared with previous conventional 3D surveys based on geophone strings and lower trace density, the main benefits were higher signal-to-noise ratio and improved vertical resolution. The enhanced amplitude preservation was a nice surprise particularly for prestack data at far offset (AVO). On the other hand, improvement in low...
On land, the conventional way of sensing reflected waves is by planting thousands of geophones at... more On land, the conventional way of sensing reflected waves is by planting thousands of geophones at the surface of the ground to isolate the usable signal from the strong background noise. These geophones deliver a voltage proportional to the ground velocity. More often than not, they are connected into receiver groups laid out as arrays to attenuate the source noise by summation of the individual voltages. However, from an operational point of view, these arrays are heavy and they require significant manpower. From a geophysical point of view, signal and noise may not be well sampled by these arrays. In addition, high frequencies are attenuated due to differential time shifts inside the groups of geophones. Obviously a step change was needed to improve operational efficiency as well as seismic imaging. With the capability of recording systems to handle an increasing number of channels, the industry is now able to record single sensors with smaller receiver intervals. Most of these si...
Everyone agrees that broadband seismic sources and receivers are essential for improved imaging a... more Everyone agrees that broadband seismic sources and receivers are essential for improved imaging and resolution, but old habits sometimes prevent operators from taking full advantage of new technology and methods that can overcome limits previously viewed as fundamental.
Denis Mougenot, Anatoly Cherepovskiy and Liu JunJie trace the development of MEMS sensors in the ... more Denis Mougenot, Anatoly Cherepovskiy and Liu JunJie trace the development of MEMS sensors in the last decade and the impact they have had on land seismic data acquisition.
Application of new technologies to Land acquisition systems has opened the way to various survey ... more Application of new technologies to Land acquisition systems has opened the way to various survey architectures. On both the source and the receiver sides, we have the option to keep field equipment centralized (e.g. cable systems) or to have it autonomous thanks to GPS synchronization (e.g. cableless systems).
Only about half of the seismic crews worldwide are equipped with vibrators, but these crews produ... more Only about half of the seismic crews worldwide are equipped with vibrators, but these crews produce more than three quarters of the seismic records. Such performance is related to the high source productivity that several fleets of vibrators sweeping alternatively and/or simultaneously made it possible. More than often these fleets are composed of a few heavy vibrators of 60,000lbf or more hydraulic peak force like Sercel Nomad-65. Thanks to their mechanical and hydraulic performances, such heavy vibrators offer the capability to widen the frequency bandwidth of the signal. Due to the strong absorption of the high frequencies, their propagation may be limited to the shallow levels, but on the low frequency side their use has been very beneficial to the seismic imaging at all depths of investigation. Emitting these low frequencies (down to 1Hz) requires tuning the Pilot sweep taking vibrator limitations into account. In this article, we describe what we think is today the most reliab...
With the dawn of this century came a new generation of seismic sensors. These are 1C or 3C MEMS b... more With the dawn of this century came a new generation of seismic sensors. These are 1C or 3C MEMS based accelerometers integrated with electronics to deliver a well calibrated digital signal. Contrary to arrays of geophones, they must be recorded individually as point receivers. Since noise is only filtered during processing, the interval between receivers must be reduced to avoid spatial aliasing of the noise and to increase fold coverage. The benefits provided by digital sensors are both operational (weight, power consumption, integration with the line...) and geophysical (amplitude & phase response, vector fidelity, tilt detection...). Early 2D-3C tests as well as 3D production surveys, including those performed by the highest channel count crews (35,000+), confirm the benefits of these new sensors: immunity to pick-up noise due to full digital transmission; increase of the frequency bandwidth of the signal and of the associated vertical resolution; well calibrated amplitude suitab...
This study focuses on the origin of prograding shelfbreaks on passive margins, using as examples ... more This study focuses on the origin of prograding shelfbreaks on passive margins, using as examples selected seismic sections recorded on Iberian Atlantic and Western Mediterranean margins. Five main factors appear to control shelf progradation: (1) the amount and nature of sediment contributed to the outer shelf; (2) the equilibrium depth H at which sedimentary particles come to rest, a factor depending on grain-size distribution and specific hydrodynamic conditions at the depositional site (according to the models presented herein, H is the shelfbreak depth); (3) the morphology of the margin, i.e. the shelfbreak is significantly prograding only where the shelf forms on a slightly inclined slope or a marginal plateau; (4) the geological activity of the margin, i.e. prograding shelves have a sigmoid configuration on young subsiding margins, and an oblique configuration on mature, slowly subsiding margins; (5) the eustatic sealevel changes, i.e. the shelfbreak is eroded during periods of low sealevel and is built-up and progrades during periods of high sealevel. In sum, the prograding outer edge of shelves provides a fairly reliable record of Quaternary sealevel changes and of the geological evolution of margins, of which they are an integral part.
Our attraction to the mineral world is stimulated by the wide range of chromatic compositions fou... more Our attraction to the mineral world is stimulated by the wide range of chromatic compositions found in the stones. Tuscany holds the most emblematic of these curiosities. Paesina stones , with their famous ruin sceneries ), have decorated many cabinets of curiosity since the 16th century.Less known, Verde d'Arno stones, with their abstract triangular compositions , are highly prized for their delicate shades of green. But the most original of these pictural stones were only discovered in 1988, in the form of pebbles ("Ciottoli" in Italian), on the beaches of Tuscany. These are the "Giottoli", as baptized by Roberto Mari, because they are pebbles painted by nature in the colors of Giotto , the Italian master of the early Renaissance. They exhibit a large chromatic diversity related to the strong alteration due to the high magmatic and hydrothermal activities in this region of thinned continental crust.
A serpentinite diapir made of altered plagioclase-bearing lherzolites, has been emplaced west of ... more A serpentinite diapir made of altered plagioclase-bearing lherzolites, has been emplaced west of the Galicia Bank at the boundary between oceanic crust and the probable thinned continental crust, that underlies the Iberian margin. ... 2J.R. Vanney, JL Auxietre and JP Dunand, ...
Extensional Tectonics and Stratigraphy of the North Atlantic Margins, 1989
A multichannel seismic survey of the Tagus abyssal plain defines the extent of oceanic crust and ... more A multichannel seismic survey of the Tagus abyssal plain defines the extent of oceanic crust and the continent-ocean boundary. This boundary is marked by landward-dipping reflectors. The oceanic domain is divided into two parts: a deep eastern basin, where an abandoned earliest Cretaceous spreading center is inferred, and a shallower western basin formed after a ridge jump. This latter oceanic domain may have a western complement in the Newfoundland basin.
Methode d'acquisition et de traitement de donnees sismiques, utilisee dans le cadre d'une... more Methode d'acquisition et de traitement de donnees sismiques, utilisee dans le cadre d'une surveillance repetitive du deplacement des fluides impregnant un reservoir (1) situe en profondeur dans le sous-sol. Selon l'invention, elle comporte les etapes consistant a amenager en chaque point d'une grille predeterminee en surface, un trou (100) vertical et de faible profondeur dans le sous-sol au-dessus du reservoir et traversant la zone d'alteration superficielle (2) ; positionner verticalement dans chaque trou des recepteurs (101,102,103,104,105,106,107,108) fixes, destines a etre connectes separement a un enregistreur (300) place en surface ; emettre a proximite de la verticale de chaque trou des ondes sismiques dans le sous-sol au moyen d'une source (200) placee en surface ; enregistrer pour chaque trou, au moyen des recepteurs, les ondes sismiques incidentes directes (10) et les ondes sismiques reflechies (20) aux interfaces des couches profondes, chaque rece...
In 1986 the french submersible Nautile dived to 3.500 m-5.500 m at Galicia Margin in the area dri... more In 1986 the french submersible Nautile dived to 3.500 m-5.500 m at Galicia Margin in the area drilled by the JOIDES Resolution O-V (CDP, Leg 103). Three different kinds of seafloor were investigated: a) the Galicia passive margin (basement and sediments); b) a basa/tic seafloor (probably a piece of Cretaceous oceanic crust of the Biscay Bay; c) a 100 km long belt of serpentinized peridotites (ultramafic seafloor) extended between the oceanic and the thinned continental crust
Dredge samples of Upper Jurassic-lowest Cretaceous limestones were recovered from western Galicia... more Dredge samples of Upper Jurassic-lowest Cretaceous limestones were recovered from western Galicia margin. Lime-stones include benthic and/or planktonic assemblages, which were deposited in environments ranging from inner to outer shelf or upper slope.
Land recording systems are composed of many receiver-points connected by cable to a central unit ... more Land recording systems are composed of many receiver-points connected by cable to a central unit for synchronization, real-time transmission and quality control of the seismic data. With the growing amount of channels in use and the exploration of frontier areas cable systems may become less productive. In difficult access or environmentally sensitive areas, they are complemented or replaced by cableless systems (D. Mougenot, First Break, February 2010). Such systems are not new, but they used to be expensive and quite difficult to synchronize using conventional radio antennas. Since 2005, with the availability of low cost low power consumption GPS chips used for synchronization, cableless systems have become more affordable and reliable. Today, they offer a cost effective alternative to the cable systems in some areas. In the Americas, the use of cableless systems is growing very fast while in other countries like China, India, Russia and the Middle East their use is still in infan...
In what is almost a chicken and egg analogy, someone has to commit first to move this technology ... more In what is almost a chicken and egg analogy, someone has to commit first to move this technology into widespread marine use, and eventually into even deeper waters. Equipment suppliers and service providers have shown their faith in the technology, as evidenced by multi-client ocean bottom cable (OBC) surveys and the recent introduction of 2,000-m (6,500-ft) rated OBC systems. For its part, BP has just contracted Seabed Geophysical AS, a Norwegian seismic contractor that specializes in 4C systems, to develop, build and test a prototype multicomponent system. Although this occurred too close to press time to cover and details may be too tentative and proprietary in any case the system will be a 4C, 250-node autonomous deployment designed to operate in 3,000-m (9,850-ft) waters.
In the Chinese domestic market, the main seismic contractors have been early adopters of MEMS-bas... more In the Chinese domestic market, the main seismic contractors have been early adopters of MEMS-based accelerometers. With the active support of the national oil companies they recorded single-sensor 3D as early as 2004. Today, the many surveys acquired with these 1C or 3C digital sensors cover a full fold area of about 2000 km2, mainly in the northern and central parts of China. All these surveys were shot with explosives (up to 10kg). The receiver interval was from 10 to 50m, and spreads requiring up to 11,520 RP’s were used. The resulting trace density ranged from 105,000 traces/km2 for the early surveys up to 7.2 million traces/km2 for the most recent ones. Compared with previous conventional 3D surveys based on geophone strings and lower trace density, the main benefits were higher signal-to-noise ratio and improved vertical resolution. The enhanced amplitude preservation was a nice surprise particularly for prestack data at far offset (AVO). On the other hand, improvement in low...
On land, the conventional way of sensing reflected waves is by planting thousands of geophones at... more On land, the conventional way of sensing reflected waves is by planting thousands of geophones at the surface of the ground to isolate the usable signal from the strong background noise. These geophones deliver a voltage proportional to the ground velocity. More often than not, they are connected into receiver groups laid out as arrays to attenuate the source noise by summation of the individual voltages. However, from an operational point of view, these arrays are heavy and they require significant manpower. From a geophysical point of view, signal and noise may not be well sampled by these arrays. In addition, high frequencies are attenuated due to differential time shifts inside the groups of geophones. Obviously a step change was needed to improve operational efficiency as well as seismic imaging. With the capability of recording systems to handle an increasing number of channels, the industry is now able to record single sensors with smaller receiver intervals. Most of these si...
Everyone agrees that broadband seismic sources and receivers are essential for improved imaging a... more Everyone agrees that broadband seismic sources and receivers are essential for improved imaging and resolution, but old habits sometimes prevent operators from taking full advantage of new technology and methods that can overcome limits previously viewed as fundamental.
Denis Mougenot, Anatoly Cherepovskiy and Liu JunJie trace the development of MEMS sensors in the ... more Denis Mougenot, Anatoly Cherepovskiy and Liu JunJie trace the development of MEMS sensors in the last decade and the impact they have had on land seismic data acquisition.
Application of new technologies to Land acquisition systems has opened the way to various survey ... more Application of new technologies to Land acquisition systems has opened the way to various survey architectures. On both the source and the receiver sides, we have the option to keep field equipment centralized (e.g. cable systems) or to have it autonomous thanks to GPS synchronization (e.g. cableless systems).
Only about half of the seismic crews worldwide are equipped with vibrators, but these crews produ... more Only about half of the seismic crews worldwide are equipped with vibrators, but these crews produce more than three quarters of the seismic records. Such performance is related to the high source productivity that several fleets of vibrators sweeping alternatively and/or simultaneously made it possible. More than often these fleets are composed of a few heavy vibrators of 60,000lbf or more hydraulic peak force like Sercel Nomad-65. Thanks to their mechanical and hydraulic performances, such heavy vibrators offer the capability to widen the frequency bandwidth of the signal. Due to the strong absorption of the high frequencies, their propagation may be limited to the shallow levels, but on the low frequency side their use has been very beneficial to the seismic imaging at all depths of investigation. Emitting these low frequencies (down to 1Hz) requires tuning the Pilot sweep taking vibrator limitations into account. In this article, we describe what we think is today the most reliab...
With the dawn of this century came a new generation of seismic sensors. These are 1C or 3C MEMS b... more With the dawn of this century came a new generation of seismic sensors. These are 1C or 3C MEMS based accelerometers integrated with electronics to deliver a well calibrated digital signal. Contrary to arrays of geophones, they must be recorded individually as point receivers. Since noise is only filtered during processing, the interval between receivers must be reduced to avoid spatial aliasing of the noise and to increase fold coverage. The benefits provided by digital sensors are both operational (weight, power consumption, integration with the line...) and geophysical (amplitude & phase response, vector fidelity, tilt detection...). Early 2D-3C tests as well as 3D production surveys, including those performed by the highest channel count crews (35,000+), confirm the benefits of these new sensors: immunity to pick-up noise due to full digital transmission; increase of the frequency bandwidth of the signal and of the associated vertical resolution; well calibrated amplitude suitab...
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Papers by Denis Mougenot
Five main factors appear to control shelf progradation:
(1) the amount and nature of sediment contributed to the outer shelf;
(2) the equilibrium depth H at which sedimentary particles come to rest, a factor depending on grain-size distribution and specific hydrodynamic conditions at the depositional site (according to the models presented herein, H is the shelfbreak depth);
(3) the morphology of the margin, i.e. the shelfbreak is significantly prograding only where the shelf forms on a slightly inclined slope or a marginal plateau;
(4) the geological activity of the margin, i.e. prograding shelves have a sigmoid configuration on young subsiding margins, and an oblique configuration on mature, slowly subsiding margins;
(5) the eustatic sealevel changes, i.e. the shelfbreak is eroded during periods of low sealevel and is built-up and progrades during periods of high sealevel.
In sum, the prograding outer edge of shelves provides a fairly reliable record of Quaternary sealevel changes and of the geological evolution of margins, of which they are an integral part.
Five main factors appear to control shelf progradation:
(1) the amount and nature of sediment contributed to the outer shelf;
(2) the equilibrium depth H at which sedimentary particles come to rest, a factor depending on grain-size distribution and specific hydrodynamic conditions at the depositional site (according to the models presented herein, H is the shelfbreak depth);
(3) the morphology of the margin, i.e. the shelfbreak is significantly prograding only where the shelf forms on a slightly inclined slope or a marginal plateau;
(4) the geological activity of the margin, i.e. prograding shelves have a sigmoid configuration on young subsiding margins, and an oblique configuration on mature, slowly subsiding margins;
(5) the eustatic sealevel changes, i.e. the shelfbreak is eroded during periods of low sealevel and is built-up and progrades during periods of high sealevel.
In sum, the prograding outer edge of shelves provides a fairly reliable record of Quaternary sealevel changes and of the geological evolution of margins, of which they are an integral part.