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Ramadan Ghalayini - One of the best experts on this subject based on the ideXlab platform.
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Structural modelling of the complex Cenozoic zone of the Levant Basin offshore Lebanon
2015Co-Authors: Ramadan GhalayiniAbstract:The Levant Basin is located at the easternmost Mediterranean at the intersection of three major tectonic plates (Africa, Arabia, Eurasia and the smaller Anatolian microplate). The Levant Fracture System (Arabia-Africa plate boundary) borders the basin to its east and represents a 1000 km long left-lateral transform System linking rifting in the Red Sea with plate convergence along the Taurus Mountains (Arabia-Eurasia plate boundary). The Levant Basin is bordered to the north by the Cyprus Arc (Africa-Eurasia plate boundary). The interaction between these tectonic plates had important consequences on the evolution of the Levant Basin whereby its eastern boundary has been affected by deformation along the Levant Fracture System. This major plate boundary is associated with a restraining bend in Lebanon and has been active since the Late Miocene. Until recent days, the absence of seismic data in the central Levant Basin was an obstacle against characterizing the tectonic setting of the basin. In this area, the geometry, kinematics and the age of the tectonic structures are poorly understood. A focal question thus remains on how the Levant Basin was affected by this adjacent plate boundary. Therefore, what is the impact of the deformation along the Levant Fracture System since the Late Miocene on this basin and how can we assess it? Has the latter been affected by other tectonic regimes prior to the onset of transpression? If so, how would the existing structures influence the style of modern deformation? In this study, high quality 2D and 3D seismic reflection data (with two 4290 m3 3D seismic cubes and seven 830 km long 2D seismic lines) were interpreted allowing identification and timing of the structures in the Levant Basin offshore Lebanon. Several fault families, mapped along the margin, are remnants of a lasting and complex tectonic history since Mesozoic times. These include NNE-SSW striking thrust faults active during the early Tertiary and inactive since the Pliocene; NNE-SSW striking anticlines folded during the Late Miocene and overlying pre-existing structuresd; and ENE-WSW striking dextral strike-slip faults inherited from Mesozoic times and reactivated during the Late Miocene. Only the dextral strike-slip faults show evidence of current activity and are interpreted to be linked to transpression along the Levant Fracture System. They constitute the westward extension of the plate boundary, formed under a transpressif regime and a NW-SE compression. We have showed how this plate boundary has evolved through the Neogene with a decrease in the shortening component during the Pliocene.The identification of pre-existing structures along the eastern Levant margin shed the light on the deep structuration affecting this area, inherited from Mesozoic tectonic events. The impact of these structures was tested through analogue modeling. Results indicated a considerable impact of pre-existing structures on the development of the restraining bend, localizing deformation at the onset of transpression and responsible of segmenting the restraining bend along an ENE direction. These ENE-WSW faults are thus major and are most likely associated with the deformation affecting the Palmyra basin since the Mesozoic, which is thus extending westward to Lebanon. This study has shown the important role of a margin on a strike-slip plate boundary. Namely, the development of antithetic faults (local dextral strike-slip faults in a regional sinistral strike-slip plate boundary) known in other similar plate boundaries is associated with a deep crustal anisotropy localizing the subsequent deformation.
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impact of cenozoic strike slip tectonics on the evolution of the northern levant basin offshore lebanon
Tectonics, 2014Co-Authors: Ramadan Ghalayini, Catherine Homberg, Jean-marc Daniel, Fadi H Nader, John E ComstockAbstract:Sedimentary basins adjacent to plate boundaries contain key tectonic and stratigraphic elements to understand how stress is transmitted through plates. The Levant Basin is a place of choice to study such elements because it flanks the Levant Fracture System and the Africa/Anatolia boundary. This paper uses new high-quality 3-D seismic reflection data to unravel the tectonic evolution of the margin of this basin during the Cenozoic, the period corresponding to the formation of the Levant Fracture System, part of the Africa/Arabia plate boundary. Four major groups of structures are identified in the interpreted Cenozoic units: NW-SE striking normal faults, NNE-SSW striking thrust-faults, ENE-WSW striking dextral strike-slip faults, and NNE trending anticlines. We demonstrate that all structures, apart of the NW-SE striking normal faults, are inherited from Mesozoic faults. Their reactivation and associated folding started during the late Miocene prior to the Messinian salinity crisis due to a NW-SE compressional stress field. No clear evidence of shortening at present-day offshore Lebanon and no large NNE-SSW strike-slip faults parallel to the restraining bend are found indicating that the Levant Fracture System is mainly contained onshore at present day. The intermittent activity of the interpreted structures correlates with the two stages of Levant Fracture System movement during late Miocene and Pliocene. This paper provides a good example of the impact of the evolution of plate boundaries on adjacent basins and indicates that any changes in the stress field, as controlled by the plate boundary, will affect immediately the preexisting structures in adjacent basins.
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impact of cenozoic strike slip tectonics on the evolution of the northern levant basin offshore lebanon
Tectonics, 2014Co-Authors: Ramadan Ghalayini, Catherine Homberg, Jean-marc Daniel, Fadi H Nader, John E ComstockAbstract:Sedimentary basins adjacent to plate boundaries contain key tectonic and stratigraphic elements to understand how stress is transmitted through plates. The Levant Basin is a place of choice to study such elements because it flanks the Levant Fracture System and the Africa/Anatolia boundary. This paper uses new high-quality 3-D seismic reflection data to unravel the tectonic evolution of the margin of this basin during the Cenozoic, the period corresponding to the formation of the Levant Fracture System, part of the Africa/Arabia plate boundary. Four major groups of structures are identified in the interpreted Cenozoic units: NW-SE striking normal faults, NNE-SSW striking thrust-faults, ENE-WSW striking dextral strike-slip faults, and NNE trending anticlines. We demonstrate that all structures, apart of the NW-SE striking normal faults, are inherited from Mesozoic faults. Their reactivation and associated folding started during the late Miocene prior to the Messinian salinity crisis due to a NW-SE compressional stress field. No clear evidence of shortening at present-day offshore Lebanon and no large NNE-SSW strike-slip faults parallel to the restraining bend are found indicating that the Levant Fracture System is mainly contained onshore at present day. The intermittent activity of the interpreted structures correlates with the two stages of Levant Fracture System movement during late Miocene and Pliocene. This paper provides a good example of the impact of the evolution of plate boundaries on adjacent basins and indicates that any changes in the stress field, as controlled by the plate boundary, will affect immediately the preexisting structures in adjacent basins.
Jizhen Zhang - One of the best experts on this subject based on the ideXlab platform.
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quantitative characterization of pore Fracture System of organic rich marine continental shale reservoirs a case study of the upper permian longtan formation southern sichuan basin china
Fuel, 2017Co-Authors: Jizhen Zhang, Xianqing Li, Wanle Liang, Zhe Wang, Feiyu WangAbstract:Abstract Although significant progress has been achieved in characterizing marine shale reservoirs, studies that are associated with marine-continental shale reservoirs, particularly quantitative characterizations of shale pore–Fracture, remain rare. In this study, 12 black organic-rich marine-continental shale samples were collected from seven wells that were recently drilled in the Upper Permian Longtan Formation in the Southern Sichuan Basin of southern China. X-ray diffraction revealed that clay minerals are the most prevalent component of shale, followed by quartz and calcite. Various pore types were classified and morphologically characterized from images that were obtained with field emission scanning electron microscopy. Shale total porosity, which was measured via mercury injection porosimetry, was between 3.1% and 7.5%. In addition, a pore-Fracture interpretation model was built to calculate Fractures and matrix porosity, including organic matter porosity, interparticle porosity of brittle minerals, and intraparticle porosity of clay minerals. The model was highly consistent with the measured porosity. Three key parameters were obtained to characterize the development of different types of matrix pores ( V TOC > V Bri > V Clay ). Low-pressure N 2 and CO 2 gas adsorption experiments were conducted to analyze pore volume, special surface area (SSA), and pore-size diameter. The results of the analyses revealed that micropores and macropores (including micro-Fractures) are the dominant pores of the Longtan shale reservoir and that micropores provide the dominant shale gas adsorption space. Furthermore, the effects of shale components on pore development, as well as the correlation among different pore structural parameters, were discussed. The results showed that the enrichment of total organic carbon and clay mineral content will benefit the development of the Longtan shale pore–Fracture System. Moreover, a good positive linear relationship existed among matrix porosity, pore volume, SSA, average pore diameter, and surface porosity.
Xiaochun Jin - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of proppant settling in complex hydraulic natural Fracture System in shale reservoirs
Journal of Natural Gas Science and Engineering, 2016Co-Authors: Qingzhi Wen, Shuting Wang, Xiaofei Duan, Feng Wang, Xiaochun JinAbstract:Abstract The general development mode of shale gas reservoirs, as an unconventional resource, cannot yield good results. Hydraulic fracturing is a widely used method in the development of unconventional reservoirs. This method’s nature is to create hydraulic Fractures in the reservoir, providing a flow path for oil and gas. To achieve a satisfying output, Fracture dimensions matter greatly, as well as the Fracture effective period. Maintaining these parameters requires that proppant can be distributed in Fracture Systems abundantly and evenly such that reservoirs can have durable Fractures with good conductivity. Shale gas reservoirs have small porosity and permeability. Gas contained in them is difficult to exploit; thus, massive stimulation methods are needed. Conventional fracturing usually aims to create a long single planar Fracture in a reservoir, while in shale gas reservoirs, complicated Fracture networks are needed. Thus, the fracturing method in shale gas reservoirs should take natural Fractures into consideration, link original micro-Fractures in the reservoir, and increase the drainage area as much as possible. This type of fracturing method is called volume fracturing. Volume fracturing can also create multiple artificial Fractures perpendicular to the main Fracture, improving the stimulation effect and extending the stimulation effective period. Proppant distribution is critical to maintaining Fracture network conductivity and enhancing a shale gas reservoir’s output. Moreover, proppant migration and settling during fracturing can affect the activation of natural Fractures and the formation of Fracture networks greatly, as well as the final effective Fracture geometry. The body of research concerning proppant’s distribution law in conventional single Fractures is quite mature, but the distribution law in complicated Fracture networks has not been thoroughly elucidated. Obviously, the current understanding cannot satisfy the demand of practical stimulation. This paper considers the difference of the proppant distribution law between complicated Fracture networks and conventional Fractures and uses a self-designed complex Fracture network simulation device to study proppant migration and the settling law in a complicated Fracture network. The research results provide theoretical support for fracturing design in shale gas reservoirs.
Huilin Xing - One of the best experts on this subject based on the ideXlab platform.
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Numerical modelling of fracturing effect stimulated by pulsating hydraulic fracturing in coal seam gas reservoir
Journal of Natural Gas Science and Engineering, 2017Co-Authors: Yupeng Jiang, Huilin XingAbstract:Abstract Pulsating hydraulic fracturing (PHF) technology is an advanced permeability enhancement method for coal seam gas mining. Laboratory and field experiments indicate that PHF can stimulate a well-distributed Fracture System inside a coal reservoir. However, the basic mechanism behind this effect is still poorly understood. In this study, a better mathematical model for pressure ripple propagation is proposed and an analytical solution is obtained. Furthermore, the particle flow code is applied based on the analytical solution to numerically simulate the fracturing effect of PHF. The mechanism for Fracture System formation with the original coal cleat System is quantitatively analysed by using advanced indicators (crack event density, crack intensity rate and kinetic energy). A new cracking pattern is proposed and discussed. Eventually, fracturing effects under different engineering PHF inputs (i.e., pulsating frequency and ripple amplitude) are numerically simulated and analysed. The conclusions build a theoretical basis for the mechanism of PHF effect. The PHF parameters may also be largely improved and optimized for the extension and formation of Fracture networks in a coal seam gas reservoir.
Feiyu Wang - One of the best experts on this subject based on the ideXlab platform.
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quantitative characterization of pore Fracture System of organic rich marine continental shale reservoirs a case study of the upper permian longtan formation southern sichuan basin china
Fuel, 2017Co-Authors: Jizhen Zhang, Xianqing Li, Wanle Liang, Zhe Wang, Feiyu WangAbstract:Abstract Although significant progress has been achieved in characterizing marine shale reservoirs, studies that are associated with marine-continental shale reservoirs, particularly quantitative characterizations of shale pore–Fracture, remain rare. In this study, 12 black organic-rich marine-continental shale samples were collected from seven wells that were recently drilled in the Upper Permian Longtan Formation in the Southern Sichuan Basin of southern China. X-ray diffraction revealed that clay minerals are the most prevalent component of shale, followed by quartz and calcite. Various pore types were classified and morphologically characterized from images that were obtained with field emission scanning electron microscopy. Shale total porosity, which was measured via mercury injection porosimetry, was between 3.1% and 7.5%. In addition, a pore-Fracture interpretation model was built to calculate Fractures and matrix porosity, including organic matter porosity, interparticle porosity of brittle minerals, and intraparticle porosity of clay minerals. The model was highly consistent with the measured porosity. Three key parameters were obtained to characterize the development of different types of matrix pores ( V TOC > V Bri > V Clay ). Low-pressure N 2 and CO 2 gas adsorption experiments were conducted to analyze pore volume, special surface area (SSA), and pore-size diameter. The results of the analyses revealed that micropores and macropores (including micro-Fractures) are the dominant pores of the Longtan shale reservoir and that micropores provide the dominant shale gas adsorption space. Furthermore, the effects of shale components on pore development, as well as the correlation among different pore structural parameters, were discussed. The results showed that the enrichment of total organic carbon and clay mineral content will benefit the development of the Longtan shale pore–Fracture System. Moreover, a good positive linear relationship existed among matrix porosity, pore volume, SSA, average pore diameter, and surface porosity.
