The Beibu Gulf Basin is an important oil-and gas-bearing basin offshore the China Sea,but the geological reserves of oil and gas are not very high,and there are significant differences between different sags.Previous ...The Beibu Gulf Basin is an important oil-and gas-bearing basin offshore the China Sea,but the geological reserves of oil and gas are not very high,and there are significant differences between different sags.Previous studies have shown that the formation and accumulation of oil and gas are closely related to deep structures,especially the crustal thickness or the relative undulation characteristics between the Moho and basement,but there is a lack of specific evaluation and quantitative standards.In this paper,we first invert the depth of the Moho in the Beibu Gulf Basin using satellite gravity anomalies and calculate the crustal thickness value based on this.Then,we count and analyze the crustal thickness value as well as the stretching factor that characterizes the crustal extension and thinning degree,and find that the NWW-trending contour closure of the 28 km Moho depth or 26 km crustal thickness corresponds significantly to the Weixinan-Fushan sag belt,which has already been proven to have considerable oil and gas discoveries,with a typical feature of crustal thinning to 22 km and the stretching factor reaching 1.1.Finally,we propose a comprehensive evaluation scheme based on the entropy weight method to normalize and evaluate the statistical features of the crust,and take a comprehensive score of Si>0.5 as an evaluation indicator for an oil-gas-rich sag.Based on this research,we believe that the Haizhong sag has considerable exploratory potential,followed by the Maichen sag,while the Leidong and Haitoubei sags have relatively smaller exploratory potential.The research results will help strategic decision-making of the oil and gas exploration in the Beibu Gulf Basin and provide new perspectives for studying the relationship between deep structures and the differential distribution of oil-gas-rich sags.展开更多
Quantitative studies on the evolution and dynamics of the deepwater area of Pearl River Mouth basin （PRMB） were carried out based on the latest geological and seismic data. The study area is generally in an extensio...Quantitative studies on the evolution and dynamics of the deepwater area of Pearl River Mouth basin （PRMB） were carried out based on the latest geological and seismic data. The study area is generally in an extensional state during the Cenozoic. The major extension happened in the earlier syn-rift stages before 23 Ma and the extension after 23 Ma is negligible. Two rapid subsidence periods, 32-23 Ma and 5.3-2.6 Ma, are identified, which are related to the abrupt heat decay during margin breakup and the collision between the Philippine Sea plate and the Eurasian plate, respectively. The strongest crustal thinning in the Baiyun （白云） sag may trigger the syn-rift volcanism along the weak faulted belt around the sag. The Cenozoic tectonic evolution of the study area could be divided into five stages： rifting （～50-40 Ma）, rift-drift transition （～40-32 Ma）, early post-breakup （～32-23 Ma）, thermal subsidence （～23-5.3 Ma） and neotectonic movement （～5.3-0 Ma）.展开更多
In this article,the backstripping technique was used in studying the subsidence charac-ters of the Qiongdongnan（琼东南） basin（QDNB） in order to understand its dynamic mechanism of formation and evolution.Meanwhile...In this article,the backstripping technique was used in studying the subsidence charac-ters of the Qiongdongnan（琼东南） basin（QDNB） in order to understand its dynamic mechanism of formation and evolution.Meanwhile,the geothermal characteristics of this area were summarized,and the stretching factors（β） of the upper crust,the whole crust,and the whole lithosphere were calculated.The QDNB is characterized by high subsidence rate,high geothermal gradient,high geothermal heat flow,and the lithosphere stretching and thinning of this area are depth dependent.An asthenosphere zone must have been confined under the lithosphere of Southeast Asian continent because of the mutual subductions of the Eurasian plate,the Pacific plate,the Indian-Australian plate,and the Philippine Sea plate.These characters indicate that strong mantle convection occurred and the lower crust materials flowed away in the domain,which lead to the rapid flexural isostasy subsidence of the upper crust and the uplift of the asthenosphere.展开更多
Quantitative studies on the extension and subsidence of the Wanan Basin were carried out based on available seismic and borehole data together with regional geological data. Using balanced cross-section and backstripp...Quantitative studies on the extension and subsidence of the Wanan Basin were carried out based on available seismic and borehole data together with regional geological data. Using balanced cross-section and backstripping techniques, we reconstructed the stratigraphic deposition and tectonic evolution histories of the basin. The basin formed from the Eocene and was generally in an extensional/transtensional state except for the Late Miocene local compressoin. The major basin extension ocurred in the Oligocene and Early Miocene （before -16.3 Ma） and thereafter uniform stretch in a smaller rate. The northern and middle basin extended intensely earlier during 38.6-23.3 Ma, while the southern basin was mainly stretched during 23.3-16.3 Ma. The basin formation and development are related to alternating sinistral to dextral strike-slip motions along the Wanan Fault Zone. The dominant dynamics may be caused by the seafloor spreading of the South China Sea and the its peripheral plate interaction. The basin tectonic evolution is divided into five phases： initial rifting, main rifting, rift-drift transition, structural inversion, and thermal subsidence.展开更多
With deep sea petroleum explorations become more and more popular,some geological phenomena have emerged:extension of lower crust and upper crust is inhomogeneous;shelf break has been moved rapidly after crustal stret...With deep sea petroleum explorations become more and more popular,some geological phenomena have emerged:extension of lower crust and upper crust is inhomogeneous;shelf break has been moved rapidly after crustal stretching.These geological phenomena are important to the continental margin evolution.To investigate the thinning of the whole crust and the contribution of the upper crust versus the lower crust to the crustal stretching since the Cenozoic,we calculated the stretching factors of the upper and the lower crust based on the 13 seismic lines in the Baiyun Sag from CNOOC.The results indicated that the whole crustal thickness decreases seaward while the whole crustal stretching factor increases from shelf to slope.Our calculations showed that the lower crustal stretching factor is higher than that of the upper crust in the Baiyun Sag.In the Cenozoic,deformation of the Baiyun Sag is controlled mainly by ductile shearing rather than brittle shearing.Based on the numerical modeling,we can conclude the initial crust in the Baiyun Sag is thermally attenuated.The stretching factor(β)of the lower crust increases from the north to the south of the continental margin,indicating two stretching centers:the Baiyun Sag and the Liwan Sag.The geometry of the shelf break and theβisoline trap have the similar trend in 23.8 and 13.8 Ma,both located in the intense deforming zone of the lower crust,and therefore we conclude the stretching and flowing of the lower crust cause the displacement of the shelf break before and after 23.8 Ma.展开更多
A fault-tolerant 1-spanner is used to preserve all the minimum energy paths after node failures to cope with fault-tolerant topology control problems in wireless ad hoc networks. A fault-tolerant 1-spanner is a graph ...A fault-tolerant 1-spanner is used to preserve all the minimum energy paths after node failures to cope with fault-tolerant topology control problems in wireless ad hoc networks. A fault-tolerant 1-spanner is a graph such that the remaining graph after node failures will not only remain connected, but also have a stretch factor of one. The fault-tolerant 1-spanner is used in a localized and distributed topology control algorithm, named the k-Fault-Tolerant 1-Spanner （k-FT1S）, where each node constructs a minimum energy path tree for every local failed node set. This paper proves that the topology constructed by k-FT1S is a k-fault-tolerant 1-spanner that can tolerate up to k node failures, such that the remaining network after node failures preserves all the minimum energy paths of the remaining network gained from the initial network by removing the same failed nodes. Simulations show that the remaining network after removal of any k nodes still has the optimal energy efficiency and is competitive in terms of average logical degree, average physical degree, and average transmission radius.展开更多
基金The Scientific and Technological Project of China National Offshore Oil Corporation(CNOOC)Research Institute Co.,Ltd.under contract No.CCL2021RCPS0167KQNthe Open Fund Project for the year 2022 of National Engineering Research Center of Offshore Oil and Gas Exploration under contract No.CCL2022RCPS0794RQN.
文摘The Beibu Gulf Basin is an important oil-and gas-bearing basin offshore the China Sea,but the geological reserves of oil and gas are not very high,and there are significant differences between different sags.Previous studies have shown that the formation and accumulation of oil and gas are closely related to deep structures,especially the crustal thickness or the relative undulation characteristics between the Moho and basement,but there is a lack of specific evaluation and quantitative standards.In this paper,we first invert the depth of the Moho in the Beibu Gulf Basin using satellite gravity anomalies and calculate the crustal thickness value based on this.Then,we count and analyze the crustal thickness value as well as the stretching factor that characterizes the crustal extension and thinning degree,and find that the NWW-trending contour closure of the 28 km Moho depth or 26 km crustal thickness corresponds significantly to the Weixinan-Fushan sag belt,which has already been proven to have considerable oil and gas discoveries,with a typical feature of crustal thinning to 22 km and the stretching factor reaching 1.1.Finally,we propose a comprehensive evaluation scheme based on the entropy weight method to normalize and evaluate the statistical features of the crust,and take a comprehensive score of Si>0.5 as an evaluation indicator for an oil-gas-rich sag.Based on this research,we believe that the Haizhong sag has considerable exploratory potential,followed by the Maichen sag,while the Leidong and Haitoubei sags have relatively smaller exploratory potential.The research results will help strategic decision-making of the oil and gas exploration in the Beibu Gulf Basin and provide new perspectives for studying the relationship between deep structures and the differential distribution of oil-gas-rich sags.
基金supported jointly by the CAS Knowledge In-novation Program (No. KZCX2-YW-203)the National Basic Research Program of China (No. 2007CB411703)+2 种基金Key Labo-ratory of Marginal Sea Geology, Chinese Academy of Sciences (No. MSGL08-22)the MLR National Petroleum Resource Strategic Target Survey and Evaluation Programthe Tai-shan Scholarship Program of Shandong Province
文摘Quantitative studies on the evolution and dynamics of the deepwater area of Pearl River Mouth basin （PRMB） were carried out based on the latest geological and seismic data. The study area is generally in an extensional state during the Cenozoic. The major extension happened in the earlier syn-rift stages before 23 Ma and the extension after 23 Ma is negligible. Two rapid subsidence periods, 32-23 Ma and 5.3-2.6 Ma, are identified, which are related to the abrupt heat decay during margin breakup and the collision between the Philippine Sea plate and the Eurasian plate, respectively. The strongest crustal thinning in the Baiyun （白云） sag may trigger the syn-rift volcanism along the weak faulted belt around the sag. The Cenozoic tectonic evolution of the study area could be divided into five stages： rifting （～50-40 Ma）, rift-drift transition （～40-32 Ma）, early post-breakup （～32-23 Ma）, thermal subsidence （～23-5.3 Ma） and neotectonic movement （～5.3-0 Ma）.
基金supported by the National Natural Science Foundation of China (No. 40672089)Research Fund for the Doctoral Program of Higher Education of China (No. 20070491004)National Key Basic Research Program "973" (No. 2007CB41170502)
文摘In this article,the backstripping technique was used in studying the subsidence charac-ters of the Qiongdongnan（琼东南） basin（QDNB） in order to understand its dynamic mechanism of formation and evolution.Meanwhile,the geothermal characteristics of this area were summarized,and the stretching factors（β） of the upper crust,the whole crust,and the whole lithosphere were calculated.The QDNB is characterized by high subsidence rate,high geothermal gradient,high geothermal heat flow,and the lithosphere stretching and thinning of this area are depth dependent.An asthenosphere zone must have been confined under the lithosphere of Southeast Asian continent because of the mutual subductions of the Eurasian plate,the Pacific plate,the Indian-Australian plate,and the Philippine Sea plate.These characters indicate that strong mantle convection occurred and the lower crust materials flowed away in the domain,which lead to the rapid flexural isostasy subsidence of the upper crust and the uplift of the asthenosphere.
基金funded by the Fundamental Research Program(No.2009CB219406)of the Chinese Ministry of Sciences and Technologythe Knowledge Innovation Project(No.KZCX2-YW-229)of the Chinese Academy of Sciences
文摘Quantitative studies on the extension and subsidence of the Wanan Basin were carried out based on available seismic and borehole data together with regional geological data. Using balanced cross-section and backstripping techniques, we reconstructed the stratigraphic deposition and tectonic evolution histories of the basin. The basin formed from the Eocene and was generally in an extensional/transtensional state except for the Late Miocene local compressoin. The major basin extension ocurred in the Oligocene and Early Miocene （before -16.3 Ma） and thereafter uniform stretch in a smaller rate. The northern and middle basin extended intensely earlier during 38.6-23.3 Ma, while the southern basin was mainly stretched during 23.3-16.3 Ma. The basin formation and development are related to alternating sinistral to dextral strike-slip motions along the Wanan Fault Zone. The dominant dynamics may be caused by the seafloor spreading of the South China Sea and the its peripheral plate interaction. The basin tectonic evolution is divided into five phases： initial rifting, main rifting, rift-drift transition, structural inversion, and thermal subsidence.
基金supported by the National Science and Technology Major Project(Grant No.2011ZX05025-003-005)National Key Basic Research Development Plan(Grant No.2009CB219401)the National Natural Science Foundation of China(Grant No.41206040)
文摘With deep sea petroleum explorations become more and more popular,some geological phenomena have emerged:extension of lower crust and upper crust is inhomogeneous;shelf break has been moved rapidly after crustal stretching.These geological phenomena are important to the continental margin evolution.To investigate the thinning of the whole crust and the contribution of the upper crust versus the lower crust to the crustal stretching since the Cenozoic,we calculated the stretching factors of the upper and the lower crust based on the 13 seismic lines in the Baiyun Sag from CNOOC.The results indicated that the whole crustal thickness decreases seaward while the whole crustal stretching factor increases from shelf to slope.Our calculations showed that the lower crustal stretching factor is higher than that of the upper crust in the Baiyun Sag.In the Cenozoic,deformation of the Baiyun Sag is controlled mainly by ductile shearing rather than brittle shearing.Based on the numerical modeling,we can conclude the initial crust in the Baiyun Sag is thermally attenuated.The stretching factor(β)of the lower crust increases from the north to the south of the continental margin,indicating two stretching centers:the Baiyun Sag and the Liwan Sag.The geometry of the shelf break and theβisoline trap have the similar trend in 23.8 and 13.8 Ma,both located in the intense deforming zone of the lower crust,and therefore we conclude the stretching and flowing of the lower crust cause the displacement of the shelf break before and after 23.8 Ma.
基金Supported by the National Natural Science Foundation of China (No.60932005)
文摘A fault-tolerant 1-spanner is used to preserve all the minimum energy paths after node failures to cope with fault-tolerant topology control problems in wireless ad hoc networks. A fault-tolerant 1-spanner is a graph such that the remaining graph after node failures will not only remain connected, but also have a stretch factor of one. The fault-tolerant 1-spanner is used in a localized and distributed topology control algorithm, named the k-Fault-Tolerant 1-Spanner （k-FT1S）, where each node constructs a minimum energy path tree for every local failed node set. This paper proves that the topology constructed by k-FT1S is a k-fault-tolerant 1-spanner that can tolerate up to k node failures, such that the remaining network after node failures preserves all the minimum energy paths of the remaining network gained from the initial network by removing the same failed nodes. Simulations show that the remaining network after removal of any k nodes still has the optimal energy efficiency and is competitive in terms of average logical degree, average physical degree, and average transmission radius.
