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Shu Jiang - One of the best experts on this subject based on the ideXlab platform.
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shale gas accumulation mechanism in a syncline setting based on multiple geological factors an example of southern sichuan and the xiuwu basin in the yangtze region
Fuel, 2019Co-Authors: Kun Zhang, Zhenxue Jiang, Yizhou Huang, Shu Jiang, Yan Song, Chengzao Jia, Xiaoxue Liu, Ming WenAbstract:Abstract The determination of favorable areas for shale gas enrichment under a syncline background is an important problem that needs to be addressed. The research objects in this study are typical shale gas blocks of the southern Sichuan Basin and the Xiuwu Basin in the Yangtze region with Lower Cambrian and Upper Ordovician–Lower Silurian shales. We carried out permeability tests parallel and perpendicular to the bedding surface, permeability tests with different overburden pressures, and permeability tests and isothermal adsorption experiments under different osmotic pressures before and after the adsorption of methane parallel to the bedding surface. In addition, along with the analysis of drilling data statistics, the enrichment of marine shale gas under a syncline background was studied with respect to dip angle and burial depth. The results show that the preservation conditions of shale gas are better when the dip angle is below 10°, while they are relatively poorer at angle more than 20°. This is due to the migration of natural gas, mainly in parallel direction to the bedding surface, leading to favorable shale gas preservation with decreasing angle. Based on double effects of the overburden pressure and gas adsorption (both increase) parallel to the bedding surface on the permeability of shale, the permeability decreases. When the overburden pressure increases to 10–15 MPa, the permeability parallel to the shale layer changes suddenly and decreases to a low value, which means that under the syncline background, the drilling depth with good shale gas production capacity should be at least 1019–1529 m.
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accumulation mechanism of marine shale gas reservoir in anticlines a case study of the southern sichuan basin and xiuwu basin in the yangtze region
Geofluids, 2019Co-Authors: Yan Song, Zhenxue Jiang, Yizhou Huang, Shu Jiang, Xin Li, Pengfei Wang, Changan ShanAbstract:The study of tectonics is one of the important aspects of shale gas preservation. It is vital for understanding how to determine the enrichment regularity of marine shale gas in anticlines. This paper focuses on typical shale blocks in the southern Sichuan Basin and shale in the Upper Ordovician and the Lower Silurian. In this study, triaxial unloading tests, permeability tests perpendicular and parallel to the stratification plane, FIB-HIM tests, and inclusion analyses are carried out with real drilling data. The enrichment regularity of marine shale gas in anticlines is studied by considering 2 aspects: the angle of the limbs and the burial depth. For anticlines with adjacent Synclines, the migration regularity of shale gas is considered by 3 aspects: the dynamics, channels, and processes of migration. This study reveals that a limb angle greater than 120° reflects relatively good conditions for shale gas preservation, while limb angles lesser than 70° indicate relatively poor conditions. This study also suggests that during the process of uplift, large-scale concentrated fractures will form at a certain depth range and horizontal stress field, resulting in the large loss of shale gas. The regression equation of the fractured depth ( ) and the horizontal stress ( ) is presented as (with a correlation coefficient ). The stratification plane and the organic pores form the migration channel of natural gas that is horizontal to the stratification plane in shale. Under the condition of both anticlines and contiguous Synclines, shale gas escapes through fractures resulting from extrusion along the anticline and the uplift effect. In addition, driven by differences in the formation pressure coefficients, shale gas is capable of migrating in a short-distance stair-type style from Synclines to the adjacent anticlines. Thus, if the drilling costs allow, the well locations should be placed in the more deeply buried Synclines.
T H Bell - One of the best experts on this subject based on the ideXlab platform.
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preservation of acadian deformation and metamorphism through intense alleghanian shearing
Journal of Structural Geology, 2004Co-Authors: T H BellAbstract:The Northfield syncline in Massachusetts, USA, preserves the same Acadian succession of FIA trends (foliation intersection axes preserved in porphyroblasts) as that in Southeast Vermont, in spite of the overprinting effects of intense Alleghanian deformation and metamorphism resulting from this syncline being thrust southwards over the Pelham gneiss dome. Therefore, both regions were multiply tectonized about the same succession of directions of shortening prior to the Alleghanian, but all relics of Acadian metamorphism were obliterated in the matrix of the Northfield syncline rocks during southwards thrusting. Within the most intensely foliated rocks at the contact between the Northfield syncline and the Pelham gneiss dome, the compositional zoning within the garnet porphyroblasts was homogenized. The 55 °C increase in the rims of these garnet porphyroblasts against the matrix appears to be a product of shear heating that occurred when these rocks were thrust over the Avalonian rocks of the Pelham dome. The lack of equivalent intense Alleghanian shearing in Vermont suggests north central Massachusetts marks the upper contact of the northwest extremity of Avalon. This extremity was less than 10 km thick if it reached SE Vermont suggesting that these rocks were tectonically wedged into North America rather than simply underthrust, and that some delamination of the upper part of this portion of Avalon occurred in Alleghanian times.
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preservation of acadian deformation and metamorphism through intense alleghanian shearing
Journal of Structural Geology, 2004Co-Authors: T H Bell, Hyeong Soo KimAbstract:The Northfield syncline in Massachusetts, USA, preserves the same Acadian succession of FIA trends (foliation intersection axes preserved in porphyroblasts) as that in Southeast Vermont, in spite of the overprinting effects of intense Alleghanian deformation and metamorphism resulting from this syncline being thrust southwards over the Pelham gneiss dome. Therefore, both regions were multiply tectonized about the same succession of directions of shortening prior to the Alleghanian, but all relics of Acadian metamorphism were obliterated in the matrix of the Northfield syncline rocks during southwards thrusting. Within the most intensely foliated rocks at the contact between the Northfield syncline and the Pelham gneiss dome, the compositional zoning within the garnet porphyroblasts was homogenized. The 55 °C increase in the rims of these garnet porphyroblasts against the matrix appears to be a product of shear heating that occurred when these rocks were thrust over the Avalonian rocks of the Pelham dome. The lack of equivalent intense Alleghanian shearing in Vermont suggests north central Massachusetts marks the upper contact of the northwest extremity of Avalon. This extremity was less than 10 km thick if it reached SE Vermont suggesting that these rocks were tectonically wedged into North America rather than simply underthrust, and that some delamination of the upper part of this portion of Avalon occurred in Alleghanian times.
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Spiral and staircase inclusion trail axes within garnet and staurolite porphyroblasts from schists of the Bolton Syncline, Connecticut: timing of porphyroblast growth and the effects of fold development
Journal of Metamorphic Geology, 1997Co-Authors: T H Bell, Kenneth A. Hickey, J. WangAbstract:In the Littleton Formation, garnet porphyroblasts preserve three generations of growth that occurred before formation of the Bolton Syncline. Inclusion trails of foliations overgrown by these porphyroblasts are always truncated by the matrix foliation suggesting that garnet growth predated the matrix foliation. In contrast, many staurolite porphyroblasts grew synchronously with formation of the Bolton Syncline. However, local rim overgrowths of the matrix foliation suggest that some staurolite porphyroblasts continued to grow after development of the fold during younger crenulation producing deformations. The axes of curvature or intersection of foliations defined by inclusion trails inside the garnet porphyroblasts lie oblique to the axial plane of the Bolton Syncline but do not change orientation across it. This suggests the garnets were not rotated during the subsequent deformation associated with fold development or during even younger crenulation events. Three samples also contain a different set of axes defined by curvature of inclusion trails in the cores of garnet porphyroblasts suggesting a protracted history of garnet growth. Foliation intersection axes in staurolite porphyroblasts are consistently orientated close to the trend of the axial plane of the Bolton Syncline on both limbs of the fold. In contrast, axes defined by curvature or intersection of foliations in the rims of staurolite porphyroblasts in two samples exhibit a different trend. This phase of staurolite growth is associated with a crenulation producing deformation that postdated formation of the Bolton Syncline. Measurement of foliation intersection axes defined by inclusion trails in both garnet and staurolite porphyroblasts has enabled the timing of growth relative to one another and to the development of the Bolton Syncline to be distinguished in rocks where other approaches have not been successful. Consistent orientation of foliation intersection axes across a range of younger structures suggests that the porphyroblasts did not rotate relative to geographical coordinates during subsequent ductile deformation. Foliation intersection axes in porphyroblasts are thus useful for correlating phases of porphyroblastic growth in this region.
Noël Joyce - One of the best experts on this subject based on the ideXlab platform.
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Stratigraphy of the Haut Var Paleogene continental series (Northeastern Provence, France): New insight on the age of the ‘Sables bleutés du Haut Var’ Formation.
'Elsevier BV', 2017Co-Authors: Philip Jean, Martín-closas Carles, Vianey-liaud Monique, Tabuce Rodolphe, Léonide Philippe, Margerel Jean-pierre, Noël JoyceAbstract:International audienceThe age of the Paleogene deposits of the Haut Var (Provence, France) has been the subject of debate. Particularly, the “Calcaire à Bithynies” and the “Sables bleutés” units were ascribed either to the early Eocene or to the Oligocene. A stratigraphical clarification is required in order to precise the paleogeographical relationships of the Haut Var Paleogene sedimentary series with coeval deposits in the neighbouring southern Provence and Subalpine regions and other European domains. The study area is characterized by tectonically separated Synclines and grabens filled in by continental Paleogene deposits. Detailed mapping and lithostratigraphical logging, sedimentological and microfacies analysis have been undertaken in order to provide a reliable stratigraphical framework. Biostratigraphical subdivisions were established based on five different fossil groups: mammals, charophytes, gastropods, ostracodes, and foraminifers. Accordingly, five formations are distinguished and dated: “Calcaire à Microcodium” and “Brèche à Microcodium” (Danian); “Marnes à oeufs d’oiseaux” (Selandian(?)-earliest Ypresian); ‘Sables bleutés du Haut Var’ (early-late(?) Ypresian); and “Bourdas conglomerates” (Rupelian). Particular emphasis is given to the study of the controversial ‘Sables bleutés du Haut Var’ Formation. As a result, correlations have been established between the different syncline and graben areas where Paleocene-Eocene and Oligocene deposits occur. Terrestrial deposits (carbonate paleosols and piedmont alluvial fans) took place during Paleocene times, while fluvial (cross-bedded sands) and lacustrine carbonate deposits developed in a foreland compressional intracontinental basin surrounded by emerged areas and tectonic highs during the early Ypresian. Paleoenvironmental and paleogeographical analysis strengthen the view that a relative isolation characterized the Haut Var area during the early Eocene, probably enhancing episodes of brackish water or evaporitic sedimentation and gastropod endemism. During the late Eocene Pyrenean-Provence tectonic phase, the E-W trending Haut Var overthrusts have been emplaced posteriorly to the deposition of the ‘Sables bleutés du Haut Var’ Fm. Finally, coarse alluvial fan and local lacustrine carbonate sedimentation occurred during the Oligocene in narrow N-S trending subsident extensional grabens associated with the N-S trending Barjols Triassic uplift
Noël J. - One of the best experts on this subject based on the ideXlab platform.
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Stratigraphy of the Haut Var Paleogene continental series (Northeastern Provence, France): New insight on the age of the 'Sables bleutés du Haut Var' Formation
'Elsevier BV', 2018Co-Authors: Philip J., Vianey-liaud M., Martín-closas Carles, Tabuce R., Léonide P., Margerel J.-p., Noël J.Abstract:The age of the Paleogene deposits of the Haut Var (Provence, France) has been the subject of debate. Particularly, the ''Calcaire à Bithynies'' and the ''Sables bleutés'' units were ascribed either to the early Eocene or to the Oligocene. A stratigraphical clarification is required in order to precise the paleogeographical relationships of the Haut Var Paleogene sedimentary series with coeval deposits in the neighbouring southern Provence and Subalpine regions and other European domains. The study area is characterized by tectonically separated Synclines and grabens filled in by continental Paleogene deposits. Detailed mapping and lithostratigraphical logging, sedimentological and microfacies analysis have been undertaken in order to provide a reliable stratigraphical framework. Biostratigraphical subdivisions were established based on five different fossil groups: mammals, charophytes, gastropods, ostracodes, and foraminifers. Accordingly, five formations are distinguished and dated: ''Calcaire a` Microcodium'' and ''Brèche à Microcodium'' (Danian); ''Marnes à oeufs d'oiseaux'' (Selandian(?)-earliest Ypresian); 'Sables bleutés du Haut Var' (early-late(?) Ypresian); and ''Bourdas conglomerates'' (Rupelian). Particular emphasis is given to the study of the controversial 'Sables bleute´ s du Haut Var' Formation. As a result, correlations have been established between the different syncline and graben areas where Paleocene-Eocene and Oligocene deposits occur. Terrestrial deposits (carbonate paleosols and piedmont alluvial fans) took place during Paleocene times, while fluvial (cross-bedded sands) and lacustrine carbonate deposits developed in a foreland compressional intracontinental basin surrounded by emerged areas and tectonic highs during the early Ypresian. Paleoenvironmental and paleogeo- graphical analysis strengthen the view that a relative isolation characterized the Haut Var area during the early Eocene, probably enhancing episodes of brackish water or evaporitic sedimentation and gastropod endemism. During the late Eocene Pyrenean-Provence tectonic phase, the E-W trending Haut Var overthrusts have been emplaced posteriorly to the deposition of the 'Sables bleute´ s du Haut Var' Fm. Finally, coarse alluvial fan and local lacustrine carbonate sedimentation occurred during the Oligocene in narrow N-S trending subsident extensional grabens associated with the N-S trending Barjols Triassic uplift
Martín-closas Carles - One of the best experts on this subject based on the ideXlab platform.
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Stratigraphy of the Haut Var Paleogene continental series (Northeastern Provence, France): New insight on the age of the 'Sables bleutés du Haut Var' Formation
'Elsevier BV', 2018Co-Authors: Philip J., Vianey-liaud M., Martín-closas Carles, Tabuce R., Léonide P., Margerel J.-p., Noël J.Abstract:The age of the Paleogene deposits of the Haut Var (Provence, France) has been the subject of debate. Particularly, the ''Calcaire à Bithynies'' and the ''Sables bleutés'' units were ascribed either to the early Eocene or to the Oligocene. A stratigraphical clarification is required in order to precise the paleogeographical relationships of the Haut Var Paleogene sedimentary series with coeval deposits in the neighbouring southern Provence and Subalpine regions and other European domains. The study area is characterized by tectonically separated Synclines and grabens filled in by continental Paleogene deposits. Detailed mapping and lithostratigraphical logging, sedimentological and microfacies analysis have been undertaken in order to provide a reliable stratigraphical framework. Biostratigraphical subdivisions were established based on five different fossil groups: mammals, charophytes, gastropods, ostracodes, and foraminifers. Accordingly, five formations are distinguished and dated: ''Calcaire a` Microcodium'' and ''Brèche à Microcodium'' (Danian); ''Marnes à oeufs d'oiseaux'' (Selandian(?)-earliest Ypresian); 'Sables bleutés du Haut Var' (early-late(?) Ypresian); and ''Bourdas conglomerates'' (Rupelian). Particular emphasis is given to the study of the controversial 'Sables bleute´ s du Haut Var' Formation. As a result, correlations have been established between the different syncline and graben areas where Paleocene-Eocene and Oligocene deposits occur. Terrestrial deposits (carbonate paleosols and piedmont alluvial fans) took place during Paleocene times, while fluvial (cross-bedded sands) and lacustrine carbonate deposits developed in a foreland compressional intracontinental basin surrounded by emerged areas and tectonic highs during the early Ypresian. Paleoenvironmental and paleogeo- graphical analysis strengthen the view that a relative isolation characterized the Haut Var area during the early Eocene, probably enhancing episodes of brackish water or evaporitic sedimentation and gastropod endemism. During the late Eocene Pyrenean-Provence tectonic phase, the E-W trending Haut Var overthrusts have been emplaced posteriorly to the deposition of the 'Sables bleute´ s du Haut Var' Fm. Finally, coarse alluvial fan and local lacustrine carbonate sedimentation occurred during the Oligocene in narrow N-S trending subsident extensional grabens associated with the N-S trending Barjols Triassic uplift
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Stratigraphy of the Haut Var Paleogene continental series (Northeastern Provence, France): New insight on the age of the ‘Sables bleutés du Haut Var’ Formation.
'Elsevier BV', 2017Co-Authors: Philip Jean, Martín-closas Carles, Vianey-liaud Monique, Tabuce Rodolphe, Léonide Philippe, Margerel Jean-pierre, Noël JoyceAbstract:International audienceThe age of the Paleogene deposits of the Haut Var (Provence, France) has been the subject of debate. Particularly, the “Calcaire à Bithynies” and the “Sables bleutés” units were ascribed either to the early Eocene or to the Oligocene. A stratigraphical clarification is required in order to precise the paleogeographical relationships of the Haut Var Paleogene sedimentary series with coeval deposits in the neighbouring southern Provence and Subalpine regions and other European domains. The study area is characterized by tectonically separated Synclines and grabens filled in by continental Paleogene deposits. Detailed mapping and lithostratigraphical logging, sedimentological and microfacies analysis have been undertaken in order to provide a reliable stratigraphical framework. Biostratigraphical subdivisions were established based on five different fossil groups: mammals, charophytes, gastropods, ostracodes, and foraminifers. Accordingly, five formations are distinguished and dated: “Calcaire à Microcodium” and “Brèche à Microcodium” (Danian); “Marnes à oeufs d’oiseaux” (Selandian(?)-earliest Ypresian); ‘Sables bleutés du Haut Var’ (early-late(?) Ypresian); and “Bourdas conglomerates” (Rupelian). Particular emphasis is given to the study of the controversial ‘Sables bleutés du Haut Var’ Formation. As a result, correlations have been established between the different syncline and graben areas where Paleocene-Eocene and Oligocene deposits occur. Terrestrial deposits (carbonate paleosols and piedmont alluvial fans) took place during Paleocene times, while fluvial (cross-bedded sands) and lacustrine carbonate deposits developed in a foreland compressional intracontinental basin surrounded by emerged areas and tectonic highs during the early Ypresian. Paleoenvironmental and paleogeographical analysis strengthen the view that a relative isolation characterized the Haut Var area during the early Eocene, probably enhancing episodes of brackish water or evaporitic sedimentation and gastropod endemism. During the late Eocene Pyrenean-Provence tectonic phase, the E-W trending Haut Var overthrusts have been emplaced posteriorly to the deposition of the ‘Sables bleutés du Haut Var’ Fm. Finally, coarse alluvial fan and local lacustrine carbonate sedimentation occurred during the Oligocene in narrow N-S trending subsident extensional grabens associated with the N-S trending Barjols Triassic uplift
