A data set of 1876 three-component,P wave seismograms from 22 stations deployed at Ordos and Taih... more A data set of 1876 three-component,P wave seismograms from 22 stations deployed at Ordos and Taihang mountains was collected to investigate crust and upper mantle structure of that area. By using the array deconvolution method,the vertical,radial,and tangential receiver functions of all events are obtained. All radial receiver functions are then migrated to produce a seismic image. The image shows that from Ordos to Bohai Bay basin,the crust becomes thinner from about 52 km to 37 km,and the Moho generally dips to the west at a small angle. In central part of Ordos basin,the crust is thickest,reaching 52 km;at the eastern edge of Ordos,the thickness decreases to 43 km. From Taihang Mountain to Bohai Bay basin,the thickness of the crust changes from 45 km to 37 km. Under the Shanxi Graben,the Moho suddenly uplifts by approximately 8-10 km in comparison to that of both sides,and the rise of the Moho and the depression of the surface show a mirror-image relationship.
Analysis of the rheological features of the lithosphere in the Lower Yangtze region indicates tha... more Analysis of the rheological features of the lithosphere in the Lower Yangtze region indicates that the Theological section has the typical characteristics of continental extensional structures, i. e. the "three-layered structure" marked by two ductile layers intercalated between three brittle layers. The shallow brittle-ductile transition zone, 15 -18 km in depth, corresponds with the low-velocity, high-conductive layer of the lower crust, while the deep brittle-ductile transition zone, 28 - 32 km in depth, corresponds with the Moho. The litho-spheric strength ranges between 1. 7 × 1011 and 4. 3 ×1011 N/m, so the lithosphere is a very special low-strength lithosphere type. The geodynamic significance reflected by the rheological features of the lithosphere is consistent with the features of tectonic evolution since the Meso-Cenozoic in the Lower Yangtze region.
The South China Sea is one of the largest marginal seas in the western Pacific region,with its no... more The South China Sea is one of the largest marginal seas in the western Pacific region,with its northern margin being characterized by a passive continental margin.An understanding of the geodynamic process of the formation and evolution of this marginal sea system is vital for a solution of the related scientific issues of the geology,resource and environment in this region.Here we synthesize the recent advances in researches about thermal state and rheology of lithosphere in the northern South China Sea and its formation mechanism, along with numerical modeling of extensional basin formation.Generally,heat flow of the northern margin of the South China Sea is relatively high,with an average of 75 mW/m~(2),and is mostly derived from mantle contribution.Temperature at Moho depth is really high,and the deep geotemperature increases gradually towards the oceanic basin.The lithosphere beneath this area is associated with high temperature,low strength and intensive rheological stratification,and the lower crust is characterized by ductile flow deformation.Numerical simulation on extensional basin formation is now transitted from kinematics to dynamic modeling,focusing on the influence of the lithosphere rheology.Controversies still exist with regard to the formation mechanism of the South China Sea;the thermo-rheological evolution of the lithosphere during continental break-up is a key factor controlling the formation and evolution of the South China Sea.In the future,further studies on the dynamic evolution patterns of the thermo-rheological structure of the lithosphere are required,which is important to a better understanding of the formation of the South China Sea.
Because the interpretation of seismic data is not unique,seismic properties of typical rock sampl... more Because the interpretation of seismic data is not unique,seismic properties of typical rock samples from Jiangxi and Fujian Provinces were studied to better explain seismic data in South China in terms of the crustal structure and composition.The P-and S-wave velocities of 5 rock samples were measured using MTS-815 Rock and Concrete Mechanics Test System.The results indicate that seismic velocities of the samples increase with increasing pressure,but decrease with increasing temperature.At the same pressure and room temperature,the P-and S-wave velocities gradually decrease from marbleized limestones,through granodiorites,K-feldspar granites to siltstones.Because the highest confining pressure in the experiments is 140 MPa,the measured velocities are only comparable with seismic observations in the upper crust.To constrain interpretation of seismic data at greater depths,we calculated the seismic velocities of 39 samples based on modal compositions,elastic constants of minerals and generalized mixing rules.The Vp/Vs and Poisson,s ratios of the samples increase with decreasing contents of quartz.Compared with felsic rocks,the limestones,dolomites and marbles are characterized by high P-wave velocities,and high Vp/VS and poisson,s ratios,which provides a way to search carbonate basins beneath the granite regions in South China.
By using acoustic emission to study the paleo-tectonic events field in the north segment of the T... more By using acoustic emission to study the paleo-tectonic events field in the north segment of the Tanlu fracture,the result indicates that this area has undergone eight paleo-tectonic movements since Late Ordovician. The maximum principal stress value has been determined as 153.6 MPa. There were no or weak tectonic movements from Early Permian to the early Yanshan movement. There were four paleo-tectonic movements after Early Cretaceous. AE results show that the Yilan-Yitong and Haerbing-Changchun faults were formed in the Proterozic,then the movment stopped. The Tanlu fracture strongly moved in the Yanshan period,and became a large-scale strike-slip fault.
Qiongdongnan basin is a Tertiary extensional basin located at the northwest of the South China Se... more Qiongdongnan basin is a Tertiary extensional basin located at the northwest of the South China Sea. From Eocene to early Oligocene, the Qiongdongnan basin was over-infilled or infilled in balance. In almost all the depressions of Qiongdongnan basin, is developed the triple sand-mud-sand sedimentary architecture. During late Oligocene, Lingshui Formation was over-infilled or infilled in balance in the northern depressions with the triple sedimentary architecture of sand-mud-sand. While in the central basin, it was hungry infilled. The sedimentary architecture is characterized by only sand-mud. The Paleogene sedimentary architecture reflected the dynamic history of Qiongdongnan basin during rifting stage from Eocene to early Oligocene and late Oligocene rifting-subsiding stage. The development of Qiongdongnan basin during late Oligocene rifting-subsiding stage is closely related with the seafloor spreading of the South China Sea.
Bulletin of the Seismological Society of America, May 14, 2010
Abstract High-quality, short-period Rayleigh-wave group velocity tomography is conducted through ... more Abstract High-quality, short-period Rayleigh-wave group velocity tomography is conducted through ambient noise cross-correlation among 54 stations in the newly upgraded Xinjiang Provincial Digital Seismic Network in northwest China. The velocity maps obtained in this study give more details in most parts of Xinjiang than previous surface wave studies that mostly focused on large scale patterns in Eurasia, Asia, or the whole of China. The tomography results have a high correlation with the major tectonic and geological features in the study area. In general, low velocities are associated with the two basins, and high velocities are associated with the two mountain belts in the Xinjiang area. The southernmost part of the Tianshan mountains has the same velocity structure as that of the neighboring part of the Tarim Basin, implying that they may have the same crustal composition. The velocity in the Tarim Basin is spatially inhomogeneous, due to the fact that it comprises several sub-blocks that have different thickness of sediments and crustal layers. In the Dzungaria Basin, as the period becomes longer, the low-velocity zone shrinks toward the south, reflecting the fact that the sediments and the upper crust in the southern part of the Dzungaria Basin are thicker than in the northern part.
With the development of deep layer gas prospecting in the Jiyang depression,many new well tempera... more With the development of deep layer gas prospecting in the Jiyang depression,many new well temperature data are increasing. These data surveyed from the depth more than 3500 meters provide credible basic information to assess the deeper source rocks in particular to assess the strata temperature of the Paleogene from the Kongdian formation to the Shahejie formation. In this paper,based on temperature data,strata lithology description,stratification data and radioactivity heat generation rate of rocks survey from thousands of wells in the Jiyang depression,the current temperatures on the bottom surface of above-mentioned strata were calculated using 1D steady heat exchange formula. The results show that the temperature at the bottom of the Shahejie formation in most zones of the basin changes from 90 to 150℃,satisfying the condition for oil generation,while it is less than 90℃ for the same formation in areas of uplifts or slopes,not enough for oil generation. The Kongdian formation is possible for oil generation in temperature to some extent. It is also found that the temperature shows a close relationship with the buried depth of the formation,and increases with the increasing depth. The temperature in the sags where the sediments are relatively thick is higher than that in the uplifts and slopes with relatively thin thickness,indicating that the depth of the formation is the key for controlling its temperature,and the influence of the geo-temperature gradient is relatively smaller.
Deep basin gas trap is considered as the prospective target of gas exploration and research in re... more Deep basin gas trap is considered as the prospective target of gas exploration and research in recent decades. The exploration methods for deep basin gas trap are based on integrative study of geological theory, exploration strategy and engineering techniques. In detail, the integrative study consists of the following three indispensable aspects: ① Emphasis on study and application of geological theory for deep basin gas trap during the exploration process; ② Multi-subject integrative study on the exploration method based on the specific geological features of deep basin gas trap; ③ Improvement of drilling and production techniques. The application of the integrative exploration method for deep basin gas trap in Tongnanba Structural Belt of Sichuan Basin proved the feasibility of this method for identifying the deep basin gas trap. The geological and seismic data indicated that Chixi Syncline has formed “pressure compartment” with favorable source-reservoir-cap rock assemblage and become the prospective area for exploration of deep basin gas trap. The systematic factors/elements of deep basin gas trap were analyzed, and a geological model suitable for deep basin gas traps of Tongnanba Structural Belt was proposed. It is suggested that under the condition of regional geo-pressure transforming zone in the syncline of the structure, and the terrestrial formation from the bottom of Upper Shaximiao Formation to the top of Lower Shaximiao Formation, the local overpressure areas are the important spots for exploration of deep basin gas traps. It is recommended to make further study and to design a wildcat well in this area.
Forty-five samples taken from 53 wells in the Kuqa foreland basin, north Tarim Basin, were select... more Forty-five samples taken from 53 wells in the Kuqa foreland basin, north Tarim Basin, were selected for thermal conductivity measurement in laboratory, and the original thermal conductivity and formation thermal conductivity column were obtained based on the correction of temperature and porosity. Fifty-two heat flow values and their distribution were calculated based on the heat conduction theory and thermal resistance method.The Kuqa foreland basin is a low-heat-flow cold basin, the heat flow values of the tectonic units in the basin are 40-50 mW/m 2 , which are lower than that in other Chinese middle and large sized basins. The mountain front belt, including Yiqikelike, Dawanqi and Kela areas, has relatively high heat flow values and is the high heat flow belt in the cold basin and also a high gas production zone. In the south area, the heat flow decreases gradually from east to west. The heat flow distribution is determined by the lithosphere flexuring and fast subsiding during the Cenozoic tectonic evolution when intensive basin-mountain coupling occurred between Tarim Basin and Tianshan because of the far distance collision of the India and Eurasian Plates.
In this paper, the author reviews the progresses in the studies of the crust and uppermantle stru... more In this paper, the author reviews the progresses in the studies of the crust and uppermantle structure with the manner of deep seismic sounding(DSS), especially in the studies of the crustal model, the type of the crust-mantle boundary, the low velocity layer in crust and inhomogeneity of uppermantle. Furthermore, the author summarizes the characteristics of the deep structure beneath some typical tectonic units based on the result of some DSS throughout the world, and emphasizes that it is still necessary to combine the characteristics with the evolving history of geology in order to explore relations between the deep structure and tectonics.
Qiongdongnan Basin is a Tertiary basin developed on the northwest margin of the South China Sea;i... more Qiongdongnan Basin is a Tertiary basin developed on the northwest margin of the South China Sea;it experienced two stages of extension from Eocene to early Oligocene and during late Oligocene.Two styles of structures,half-graben and graben,developed with zonation from north to south and segmentation from east to west.From the point of mechanics and lithospheric extension,both the sinistral rotational stress associated with the Indosinian plate extrusion and the SSE stretching stress caused by the sub-duction of the ancient South China Sea controlled the rifting of Qiongdongnan Basin from Eocene to early Oligocene,while the extension during late Oligocene was caused by the spreading of the subsea basin.The thermal situation of the lithosphere determined the stretching style of the upper crust.The northern depression developed half-grabens controlled by synclined faults due to relative cold lithosphere extension,while the central depression is characterized by composite rift belts,which are composed of half-graben and graben.
The analysis of apatite fission tracks of 12 samples collected in Dongying Depressionindicates th... more The analysis of apatite fission tracks of 12 samples collected in Dongying Depressionindicates that the depression experienced a continuous cooling thermal history after its formation. Two distinct cooling processes took place during 50￣60 Ma and 20￣30 Ma respectly,and the ...
... 9, ZHANG Shimao,DING Xiaoqi,YI Chao(State Key Laboratory of Oil and Gas Reservoir Geology and... more ... 9, ZHANG Shimao,DING Xiaoqi,YI Chao(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of ... 3, Yan Zhifeng Tang Shuheng Zhu Baocun (China University of Geosciences,Beijing 100083);Analysis on the Conditions of CBM Reservoirs ...
Journal of Geophysics and Engineering, Mar 10, 2015
ABSTRACT The accuracy of hypocenter location is the essential issue for microseismic monitoring, ... more ABSTRACT The accuracy of hypocenter location is the essential issue for microseismic monitoring, and is the basis for evaluating the effect of fracture. Although the signal obtained from a borehole monitoring system has a higher signal to noise ratio (SNR) than the surface system, a narrow monitoring aperture makes the location sensitive to noise and tends to be a misguided shape. In order to overcome this disadvantage and obtain a more accurate estimation of the source, we develop a ‘jointing method’, which combines the P–S phase arrival difference and P-wave arrival difference of each receiver pair (PSP) in the objective function. In the synthetic example, we compare the noise responses of three different location methods which are based on P-wave arrival time difference, P–S wave arrival time difference and the PSP method, respectively. This analysis shows that the P-wave arrival difference method is more sensitive to arrival time error than the others and the location results tend to be in a misleading line directed to the receivers. The P–S arrival difference method is more robust than the method using P-wave and its error distribution is perpendicular to the ray-path direction. The PSP method, as expected, is the most stable and accurate. When the P–S method and PSP method are applied to field data of a coal bed methane hydro-fracture process monitoring, the results indicate that the PSP method is preferable. The successful location with the PSP method proves that it is suitable for field data.
A data set of 1876 three-component,P wave seismograms from 22 stations deployed at Ordos and Taih... more A data set of 1876 three-component,P wave seismograms from 22 stations deployed at Ordos and Taihang mountains was collected to investigate crust and upper mantle structure of that area. By using the array deconvolution method,the vertical,radial,and tangential receiver functions of all events are obtained. All radial receiver functions are then migrated to produce a seismic image. The image shows that from Ordos to Bohai Bay basin,the crust becomes thinner from about 52 km to 37 km,and the Moho generally dips to the west at a small angle. In central part of Ordos basin,the crust is thickest,reaching 52 km;at the eastern edge of Ordos,the thickness decreases to 43 km. From Taihang Mountain to Bohai Bay basin,the thickness of the crust changes from 45 km to 37 km. Under the Shanxi Graben,the Moho suddenly uplifts by approximately 8-10 km in comparison to that of both sides,and the rise of the Moho and the depression of the surface show a mirror-image relationship.
Analysis of the rheological features of the lithosphere in the Lower Yangtze region indicates tha... more Analysis of the rheological features of the lithosphere in the Lower Yangtze region indicates that the Theological section has the typical characteristics of continental extensional structures, i. e. the "three-layered structure" marked by two ductile layers intercalated between three brittle layers. The shallow brittle-ductile transition zone, 15 -18 km in depth, corresponds with the low-velocity, high-conductive layer of the lower crust, while the deep brittle-ductile transition zone, 28 - 32 km in depth, corresponds with the Moho. The litho-spheric strength ranges between 1. 7 × 1011 and 4. 3 ×1011 N/m, so the lithosphere is a very special low-strength lithosphere type. The geodynamic significance reflected by the rheological features of the lithosphere is consistent with the features of tectonic evolution since the Meso-Cenozoic in the Lower Yangtze region.
The South China Sea is one of the largest marginal seas in the western Pacific region,with its no... more The South China Sea is one of the largest marginal seas in the western Pacific region,with its northern margin being characterized by a passive continental margin.An understanding of the geodynamic process of the formation and evolution of this marginal sea system is vital for a solution of the related scientific issues of the geology,resource and environment in this region.Here we synthesize the recent advances in researches about thermal state and rheology of lithosphere in the northern South China Sea and its formation mechanism, along with numerical modeling of extensional basin formation.Generally,heat flow of the northern margin of the South China Sea is relatively high,with an average of 75 mW/m~(2),and is mostly derived from mantle contribution.Temperature at Moho depth is really high,and the deep geotemperature increases gradually towards the oceanic basin.The lithosphere beneath this area is associated with high temperature,low strength and intensive rheological stratification,and the lower crust is characterized by ductile flow deformation.Numerical simulation on extensional basin formation is now transitted from kinematics to dynamic modeling,focusing on the influence of the lithosphere rheology.Controversies still exist with regard to the formation mechanism of the South China Sea;the thermo-rheological evolution of the lithosphere during continental break-up is a key factor controlling the formation and evolution of the South China Sea.In the future,further studies on the dynamic evolution patterns of the thermo-rheological structure of the lithosphere are required,which is important to a better understanding of the formation of the South China Sea.
Because the interpretation of seismic data is not unique,seismic properties of typical rock sampl... more Because the interpretation of seismic data is not unique,seismic properties of typical rock samples from Jiangxi and Fujian Provinces were studied to better explain seismic data in South China in terms of the crustal structure and composition.The P-and S-wave velocities of 5 rock samples were measured using MTS-815 Rock and Concrete Mechanics Test System.The results indicate that seismic velocities of the samples increase with increasing pressure,but decrease with increasing temperature.At the same pressure and room temperature,the P-and S-wave velocities gradually decrease from marbleized limestones,through granodiorites,K-feldspar granites to siltstones.Because the highest confining pressure in the experiments is 140 MPa,the measured velocities are only comparable with seismic observations in the upper crust.To constrain interpretation of seismic data at greater depths,we calculated the seismic velocities of 39 samples based on modal compositions,elastic constants of minerals and generalized mixing rules.The Vp/Vs and Poisson,s ratios of the samples increase with decreasing contents of quartz.Compared with felsic rocks,the limestones,dolomites and marbles are characterized by high P-wave velocities,and high Vp/VS and poisson,s ratios,which provides a way to search carbonate basins beneath the granite regions in South China.
By using acoustic emission to study the paleo-tectonic events field in the north segment of the T... more By using acoustic emission to study the paleo-tectonic events field in the north segment of the Tanlu fracture,the result indicates that this area has undergone eight paleo-tectonic movements since Late Ordovician. The maximum principal stress value has been determined as 153.6 MPa. There were no or weak tectonic movements from Early Permian to the early Yanshan movement. There were four paleo-tectonic movements after Early Cretaceous. AE results show that the Yilan-Yitong and Haerbing-Changchun faults were formed in the Proterozic,then the movment stopped. The Tanlu fracture strongly moved in the Yanshan period,and became a large-scale strike-slip fault.
Qiongdongnan basin is a Tertiary extensional basin located at the northwest of the South China Se... more Qiongdongnan basin is a Tertiary extensional basin located at the northwest of the South China Sea. From Eocene to early Oligocene, the Qiongdongnan basin was over-infilled or infilled in balance. In almost all the depressions of Qiongdongnan basin, is developed the triple sand-mud-sand sedimentary architecture. During late Oligocene, Lingshui Formation was over-infilled or infilled in balance in the northern depressions with the triple sedimentary architecture of sand-mud-sand. While in the central basin, it was hungry infilled. The sedimentary architecture is characterized by only sand-mud. The Paleogene sedimentary architecture reflected the dynamic history of Qiongdongnan basin during rifting stage from Eocene to early Oligocene and late Oligocene rifting-subsiding stage. The development of Qiongdongnan basin during late Oligocene rifting-subsiding stage is closely related with the seafloor spreading of the South China Sea.
Bulletin of the Seismological Society of America, May 14, 2010
Abstract High-quality, short-period Rayleigh-wave group velocity tomography is conducted through ... more Abstract High-quality, short-period Rayleigh-wave group velocity tomography is conducted through ambient noise cross-correlation among 54 stations in the newly upgraded Xinjiang Provincial Digital Seismic Network in northwest China. The velocity maps obtained in this study give more details in most parts of Xinjiang than previous surface wave studies that mostly focused on large scale patterns in Eurasia, Asia, or the whole of China. The tomography results have a high correlation with the major tectonic and geological features in the study area. In general, low velocities are associated with the two basins, and high velocities are associated with the two mountain belts in the Xinjiang area. The southernmost part of the Tianshan mountains has the same velocity structure as that of the neighboring part of the Tarim Basin, implying that they may have the same crustal composition. The velocity in the Tarim Basin is spatially inhomogeneous, due to the fact that it comprises several sub-blocks that have different thickness of sediments and crustal layers. In the Dzungaria Basin, as the period becomes longer, the low-velocity zone shrinks toward the south, reflecting the fact that the sediments and the upper crust in the southern part of the Dzungaria Basin are thicker than in the northern part.
With the development of deep layer gas prospecting in the Jiyang depression,many new well tempera... more With the development of deep layer gas prospecting in the Jiyang depression,many new well temperature data are increasing. These data surveyed from the depth more than 3500 meters provide credible basic information to assess the deeper source rocks in particular to assess the strata temperature of the Paleogene from the Kongdian formation to the Shahejie formation. In this paper,based on temperature data,strata lithology description,stratification data and radioactivity heat generation rate of rocks survey from thousands of wells in the Jiyang depression,the current temperatures on the bottom surface of above-mentioned strata were calculated using 1D steady heat exchange formula. The results show that the temperature at the bottom of the Shahejie formation in most zones of the basin changes from 90 to 150℃,satisfying the condition for oil generation,while it is less than 90℃ for the same formation in areas of uplifts or slopes,not enough for oil generation. The Kongdian formation is possible for oil generation in temperature to some extent. It is also found that the temperature shows a close relationship with the buried depth of the formation,and increases with the increasing depth. The temperature in the sags where the sediments are relatively thick is higher than that in the uplifts and slopes with relatively thin thickness,indicating that the depth of the formation is the key for controlling its temperature,and the influence of the geo-temperature gradient is relatively smaller.
Deep basin gas trap is considered as the prospective target of gas exploration and research in re... more Deep basin gas trap is considered as the prospective target of gas exploration and research in recent decades. The exploration methods for deep basin gas trap are based on integrative study of geological theory, exploration strategy and engineering techniques. In detail, the integrative study consists of the following three indispensable aspects: ① Emphasis on study and application of geological theory for deep basin gas trap during the exploration process; ② Multi-subject integrative study on the exploration method based on the specific geological features of deep basin gas trap; ③ Improvement of drilling and production techniques. The application of the integrative exploration method for deep basin gas trap in Tongnanba Structural Belt of Sichuan Basin proved the feasibility of this method for identifying the deep basin gas trap. The geological and seismic data indicated that Chixi Syncline has formed “pressure compartment” with favorable source-reservoir-cap rock assemblage and become the prospective area for exploration of deep basin gas trap. The systematic factors/elements of deep basin gas trap were analyzed, and a geological model suitable for deep basin gas traps of Tongnanba Structural Belt was proposed. It is suggested that under the condition of regional geo-pressure transforming zone in the syncline of the structure, and the terrestrial formation from the bottom of Upper Shaximiao Formation to the top of Lower Shaximiao Formation, the local overpressure areas are the important spots for exploration of deep basin gas traps. It is recommended to make further study and to design a wildcat well in this area.
Forty-five samples taken from 53 wells in the Kuqa foreland basin, north Tarim Basin, were select... more Forty-five samples taken from 53 wells in the Kuqa foreland basin, north Tarim Basin, were selected for thermal conductivity measurement in laboratory, and the original thermal conductivity and formation thermal conductivity column were obtained based on the correction of temperature and porosity. Fifty-two heat flow values and their distribution were calculated based on the heat conduction theory and thermal resistance method.The Kuqa foreland basin is a low-heat-flow cold basin, the heat flow values of the tectonic units in the basin are 40-50 mW/m 2 , which are lower than that in other Chinese middle and large sized basins. The mountain front belt, including Yiqikelike, Dawanqi and Kela areas, has relatively high heat flow values and is the high heat flow belt in the cold basin and also a high gas production zone. In the south area, the heat flow decreases gradually from east to west. The heat flow distribution is determined by the lithosphere flexuring and fast subsiding during the Cenozoic tectonic evolution when intensive basin-mountain coupling occurred between Tarim Basin and Tianshan because of the far distance collision of the India and Eurasian Plates.
In this paper, the author reviews the progresses in the studies of the crust and uppermantle stru... more In this paper, the author reviews the progresses in the studies of the crust and uppermantle structure with the manner of deep seismic sounding(DSS), especially in the studies of the crustal model, the type of the crust-mantle boundary, the low velocity layer in crust and inhomogeneity of uppermantle. Furthermore, the author summarizes the characteristics of the deep structure beneath some typical tectonic units based on the result of some DSS throughout the world, and emphasizes that it is still necessary to combine the characteristics with the evolving history of geology in order to explore relations between the deep structure and tectonics.
Qiongdongnan Basin is a Tertiary basin developed on the northwest margin of the South China Sea;i... more Qiongdongnan Basin is a Tertiary basin developed on the northwest margin of the South China Sea;it experienced two stages of extension from Eocene to early Oligocene and during late Oligocene.Two styles of structures,half-graben and graben,developed with zonation from north to south and segmentation from east to west.From the point of mechanics and lithospheric extension,both the sinistral rotational stress associated with the Indosinian plate extrusion and the SSE stretching stress caused by the sub-duction of the ancient South China Sea controlled the rifting of Qiongdongnan Basin from Eocene to early Oligocene,while the extension during late Oligocene was caused by the spreading of the subsea basin.The thermal situation of the lithosphere determined the stretching style of the upper crust.The northern depression developed half-grabens controlled by synclined faults due to relative cold lithosphere extension,while the central depression is characterized by composite rift belts,which are composed of half-graben and graben.
The analysis of apatite fission tracks of 12 samples collected in Dongying Depressionindicates th... more The analysis of apatite fission tracks of 12 samples collected in Dongying Depressionindicates that the depression experienced a continuous cooling thermal history after its formation. Two distinct cooling processes took place during 50￣60 Ma and 20￣30 Ma respectly,and the ...
... 9, ZHANG Shimao,DING Xiaoqi,YI Chao(State Key Laboratory of Oil and Gas Reservoir Geology and... more ... 9, ZHANG Shimao,DING Xiaoqi,YI Chao(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Chengdu University of ... 3, Yan Zhifeng Tang Shuheng Zhu Baocun (China University of Geosciences,Beijing 100083);Analysis on the Conditions of CBM Reservoirs ...
Journal of Geophysics and Engineering, Mar 10, 2015
ABSTRACT The accuracy of hypocenter location is the essential issue for microseismic monitoring, ... more ABSTRACT The accuracy of hypocenter location is the essential issue for microseismic monitoring, and is the basis for evaluating the effect of fracture. Although the signal obtained from a borehole monitoring system has a higher signal to noise ratio (SNR) than the surface system, a narrow monitoring aperture makes the location sensitive to noise and tends to be a misguided shape. In order to overcome this disadvantage and obtain a more accurate estimation of the source, we develop a ‘jointing method’, which combines the P–S phase arrival difference and P-wave arrival difference of each receiver pair (PSP) in the objective function. In the synthetic example, we compare the noise responses of three different location methods which are based on P-wave arrival time difference, P–S wave arrival time difference and the PSP method, respectively. This analysis shows that the P-wave arrival difference method is more sensitive to arrival time error than the others and the location results tend to be in a misleading line directed to the receivers. The P–S arrival difference method is more robust than the method using P-wave and its error distribution is perpendicular to the ray-path direction. The PSP method, as expected, is the most stable and accurate. When the P–S method and PSP method are applied to field data of a coal bed methane hydro-fracture process monitoring, the results indicate that the PSP method is preferable. The successful location with the PSP method proves that it is suitable for field data.
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Papers by Liangshu Wang