The shallow reflection surveys were carried out in 2007 and 2010 austral summers in East Ongul Island, the Lützow-Holm Complex (LHC), East Antarctica. LHC is identified by geologically as one of the Pan-African t...The shallow reflection surveys were carried out in 2007 and 2010 austral summers in East Ongul Island, the Lützow-Holm Complex (LHC), East Antarctica. LHC is identified by geologically as one of the Pan-African terrains of Eastern Dronning Maud Land. The multi-channel reflection surveys targeted to achieve the image of laminated layering of metamorphic rocks near the surface (the depths down to a few hundreds of meters) of the crystalline crust. Two surveys were conducted in total length of the profiles about 500 m along a main traffic load across the East Ongul Island. The multi-channel acquisition systems were utilized with combining the dense geophones along the profiles. Seismic sources were adopted by combining the boom of a power shovel, a weight drop and hammer shots with their intervals in a few tens of meters. The obtained data include clear first P-arrivals in far offset distance. The energy of P-S converted waves was enhanced because of the characteristics of the seismic sources. Pre-stacked images could be expected to the information on metamorphic layering for several lithological structure composed by hornblende gneiss, garnet gneiss and pyroxene gneiss appearing as the surface bedrocks. The conducted shallow reflection surveys would give rise to one step for understanding tectonic formation of LHC, as one of the Pan-African mobile belts in Gondwana super-continent.展开更多
At present, Chinas economic strength and comprehensive national strength have been constantly improved, and various social infrastructures have been constructed and improved to a great extent, and the construction sca...At present, Chinas economic strength and comprehensive national strength have been constantly improved, and various social infrastructures have been constructed and improved to a great extent, and the construction scale of engineering projects has continued to expand. In this process, surveying and mapping engineering technology has played a very important role. However, there are still some problems and shortcomings in the actual use of surveying and mapping engineering technology. Surveying and mapping technicians should pay more attention to and understand the problems, so as to formulate scientific and effective solutions and further improve the reliability of surveying and mapping engineering technology. This paper mainly analyzes and studies the technical problems of surveying and mapping engineering and puts forward specific improvement measures, so as to provide useful reference and help for relevant personnel.展开更多
The paper presents the results of a ground penetrating radar （GPR） application for the detection of ground ice. We com- bined a reflection traveltime curves analysis with a frequency spectrogram analysis. We found s...The paper presents the results of a ground penetrating radar （GPR） application for the detection of ground ice. We com- bined a reflection traveltime curves analysis with a frequency spectrogram analysis. We found special anomalies at specific traces in the traveltime curves and ground boundaries analysis, and obtained a ground model for subsurface structure which allows the ground ice layer to be identified and delineated.展开更多
It is desirable to develop new signal processing techniques for effectively extracting reflected waves under the strong interferences of borehole guided waves. We presented a multi-scale semblance method for the separ...It is desirable to develop new signal processing techniques for effectively extracting reflected waves under the strong interferences of borehole guided waves. We presented a multi-scale semblance method for the separation and velocity （slowness） analysis of the reflected waves and guided waves in borehole acoustic logging. It was specially designed for the newly developed tools with ultra-long source- receiver spacing for acoustic reflection survey. This new method was a combination of the dual tree com- plex wavelets transform （DT-CWT） and the slowness travel time coherence （STC） method. Applications to the 3D finite difference （FD） modeling simulated data and to the field array sonic waveform signals have demonstrated the ability of this method to appropriately extract the reflected waves under severe interference from the guided waves and to suppress noise in the time-frequency domain.展开更多
Dipole Shear-Wave Reflection Survey(DSRS)has gained wide application in identifying unconventional reservoirs in anisotropic formations.Previous investigations have illuminated how boreholes complicate the distributio...Dipole Shear-Wave Reflection Survey(DSRS)has gained wide application in identifying unconventional reservoirs in anisotropic formations.Previous investigations have illuminated how boreholes complicate the distribution of acoustic energy.However,these models have not accounted for the anisotropic context,rendering them insufficient for analyzing acoustic energy distribution and radiation efficiency in anisotropic formations.We derive expressions for energy flux and radiation efficiency from a borehole dipole source in the vertical-transverse isotropic(VTI)media using the Umov-Poynting vector and steepest-descent solution.Utilizing this approach,we systematically evaluate the sensitivity of anisotropic parameters to energy flux and radiation efficiency,unveiling intricate variations of these properties across frequency and anisotropic parameters.Our findings emphasize the substantial influence of formation anisotropy on energy distribution from a dipole source inside the borehole.Due to energy conversion between wave modes,five radiation wave modes are elicited by the dipole source,with the SH wave retaining its status as the prime candidate for DSRS in fast formations owing to its elevated radiation efficiency.Conversely,the qP-qP wave exhibits advantages over S waves in unconsolidated formations.A key distinction between isotropic and anisotropic media is the presence of dominant excitation frequencies in the low-frequency domain.The significance of dominant excitation-frequency bands is validated by field data,emphasizing their pivotal role.These results offer valuable insights for designing DSRS measurement strategies,which have broad application expectations for unconventional oil and gas exploration.展开更多
The application of Geographic Information System(GIS)methodologies offers valuable insights into the hydrological behaviour of watersheds through the analysis of their morphometric attributes.This study focuses on the...The application of Geographic Information System(GIS)methodologies offers valuable insights into the hydrological behaviour of watersheds through the analysis of their morphometric attributes.This study focuses on the Goriganga River,a major tributary of the Ganga River system,by conducting a detailed morphometric analysis using Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)imagery with 30 m resolution,alongside survey of India topographic sheets.Thirty-two water-sheds within the river basin were delineated to calculate linear,areal,and relief morphometric parameters,covering a total drainage area of 2,183.11 km^(2).The drainage pattern,primarily dendritic to sub-dendritic,is shaped by the region's topography,geological structure,and precipitation patterns.Classified as a 6th-order basin,the drainage density ranges from 1.21 km/km^(2)to 1.96 km/km^(2),underlining the significant influence of the regional physiography and lithological composition on the stream ordering.Relief analysis suggests the basin is in an early developmental stage,characterised by varying slope gradients and a low to moder-ate risk of soil erosion.The basin's hydrogeology is complex,with aquifer distribution primarily governed by lithological factors.Limestone,due to its high permeability and karst features,forms the principal aquifer,although it is susceptible to contamination.In contrast,groundwater potential in the Basement Gneissic Complex and Schist regions is limited to structurally controlled zones,while shale acts as an aquitard.The basin's heterogeneous aquifer characteristics emphasize the need for localized groundwater management strategies tailored to specific lithological units.The integration of remote sensing and GIS techniques effectively delineates the basin's morphometric and hydrogeological characteristics,providing critical information for the development of sustainable water resource management strategies.展开更多
文摘The shallow reflection surveys were carried out in 2007 and 2010 austral summers in East Ongul Island, the Lützow-Holm Complex (LHC), East Antarctica. LHC is identified by geologically as one of the Pan-African terrains of Eastern Dronning Maud Land. The multi-channel reflection surveys targeted to achieve the image of laminated layering of metamorphic rocks near the surface (the depths down to a few hundreds of meters) of the crystalline crust. Two surveys were conducted in total length of the profiles about 500 m along a main traffic load across the East Ongul Island. The multi-channel acquisition systems were utilized with combining the dense geophones along the profiles. Seismic sources were adopted by combining the boom of a power shovel, a weight drop and hammer shots with their intervals in a few tens of meters. The obtained data include clear first P-arrivals in far offset distance. The energy of P-S converted waves was enhanced because of the characteristics of the seismic sources. Pre-stacked images could be expected to the information on metamorphic layering for several lithological structure composed by hornblende gneiss, garnet gneiss and pyroxene gneiss appearing as the surface bedrocks. The conducted shallow reflection surveys would give rise to one step for understanding tectonic formation of LHC, as one of the Pan-African mobile belts in Gondwana super-continent.
文摘At present, Chinas economic strength and comprehensive national strength have been constantly improved, and various social infrastructures have been constructed and improved to a great extent, and the construction scale of engineering projects has continued to expand. In this process, surveying and mapping engineering technology has played a very important role. However, there are still some problems and shortcomings in the actual use of surveying and mapping engineering technology. Surveying and mapping technicians should pay more attention to and understand the problems, so as to formulate scientific and effective solutions and further improve the reliability of surveying and mapping engineering technology. This paper mainly analyzes and studies the technical problems of surveying and mapping engineering and puts forward specific improvement measures, so as to provide useful reference and help for relevant personnel.
文摘The paper presents the results of a ground penetrating radar （GPR） application for the detection of ground ice. We com- bined a reflection traveltime curves analysis with a frequency spectrogram analysis. We found special anomalies at specific traces in the traveltime curves and ground boundaries analysis, and obtained a ground model for subsurface structure which allows the ground ice layer to be identified and delineated.
基金National Natural Science Foundation of China (the project No.is 50674098)the National 863 Project of China (Grant 2006AA06Z207)theNational Basic Research Program of China (973 Program,2007CB209601).
文摘It is desirable to develop new signal processing techniques for effectively extracting reflected waves under the strong interferences of borehole guided waves. We presented a multi-scale semblance method for the separation and velocity （slowness） analysis of the reflected waves and guided waves in borehole acoustic logging. It was specially designed for the newly developed tools with ultra-long source- receiver spacing for acoustic reflection survey. This new method was a combination of the dual tree com- plex wavelets transform （DT-CWT） and the slowness travel time coherence （STC） method. Applications to the 3D finite difference （FD） modeling simulated data and to the field array sonic waveform signals have demonstrated the ability of this method to appropriately extract the reflected waves under severe interference from the guided waves and to suppress noise in the time-frequency domain.
基金supported by the National Natural Science Foundation of China(grant No.42074137,42204126,41821002,U21B2064)Laoshan National Laboratory Science and Technology Innovation Project(grant No.LSKJ202203407)China Scholarship Council State Scholarship Fund(202206450061)。
文摘Dipole Shear-Wave Reflection Survey(DSRS)has gained wide application in identifying unconventional reservoirs in anisotropic formations.Previous investigations have illuminated how boreholes complicate the distribution of acoustic energy.However,these models have not accounted for the anisotropic context,rendering them insufficient for analyzing acoustic energy distribution and radiation efficiency in anisotropic formations.We derive expressions for energy flux and radiation efficiency from a borehole dipole source in the vertical-transverse isotropic(VTI)media using the Umov-Poynting vector and steepest-descent solution.Utilizing this approach,we systematically evaluate the sensitivity of anisotropic parameters to energy flux and radiation efficiency,unveiling intricate variations of these properties across frequency and anisotropic parameters.Our findings emphasize the substantial influence of formation anisotropy on energy distribution from a dipole source inside the borehole.Due to energy conversion between wave modes,five radiation wave modes are elicited by the dipole source,with the SH wave retaining its status as the prime candidate for DSRS in fast formations owing to its elevated radiation efficiency.Conversely,the qP-qP wave exhibits advantages over S waves in unconsolidated formations.A key distinction between isotropic and anisotropic media is the presence of dominant excitation frequencies in the low-frequency domain.The significance of dominant excitation-frequency bands is validated by field data,emphasizing their pivotal role.These results offer valuable insights for designing DSRS measurement strategies,which have broad application expectations for unconventional oil and gas exploration.
文摘The application of Geographic Information System(GIS)methodologies offers valuable insights into the hydrological behaviour of watersheds through the analysis of their morphometric attributes.This study focuses on the Goriganga River,a major tributary of the Ganga River system,by conducting a detailed morphometric analysis using Advanced Spaceborne Thermal Emission and Reflection Radiometer(ASTER)imagery with 30 m resolution,alongside survey of India topographic sheets.Thirty-two water-sheds within the river basin were delineated to calculate linear,areal,and relief morphometric parameters,covering a total drainage area of 2,183.11 km^(2).The drainage pattern,primarily dendritic to sub-dendritic,is shaped by the region's topography,geological structure,and precipitation patterns.Classified as a 6th-order basin,the drainage density ranges from 1.21 km/km^(2)to 1.96 km/km^(2),underlining the significant influence of the regional physiography and lithological composition on the stream ordering.Relief analysis suggests the basin is in an early developmental stage,characterised by varying slope gradients and a low to moder-ate risk of soil erosion.The basin's hydrogeology is complex,with aquifer distribution primarily governed by lithological factors.Limestone,due to its high permeability and karst features,forms the principal aquifer,although it is susceptible to contamination.In contrast,groundwater potential in the Basement Gneissic Complex and Schist regions is limited to structurally controlled zones,while shale acts as an aquitard.The basin's heterogeneous aquifer characteristics emphasize the need for localized groundwater management strategies tailored to specific lithological units.The integration of remote sensing and GIS techniques effectively delineates the basin's morphometric and hydrogeological characteristics,providing critical information for the development of sustainable water resource management strategies.
