The East China Sea Shelf Basin,especially the Xihu depression in its northeastern region,has long been regarded as an important target area for oil and gas exploration in China.Since the development of the late Cretac...The East China Sea Shelf Basin,especially the Xihu depression in its northeastern region,has long been regarded as an important target area for oil and gas exploration in China.Since the development of the late Cretaceous,this region has experienced complex and multistage tectonic movements,such as extensional faulting and compressional inversion,forming its current unique geological structure pattern.As one of the largest Mesozoic–Cenozoic sedimentary basins offshore China,the East China Sea Shelf Basin not only contains abundant oil and gas resources but also occupies a key strategic position.In addition,it is gradually becoming an important base and strategic core area for China's oil and gas resource development.Although remarkable progress has been achieved in oil and gas exploration,seismic exploration in the Xihu depression still faces many challenges.Especially in deep target layers,weak seismic reflection energy,low signal-to-noise ratio,and poor wave group continuity seriously affect the efficiency and accuracy of oil and gas exploration.In addition,given the considerable influence of folds and faults in the East China Sea Xihu Basin,transverse anisotropy is widespread,which causes difficulty for conventional imaging technologies based on isotropic assumptions to achieve accurate imaging.Therefore,to address these challenges and meet the need for accurate imaging of complex structures in the Xihu depression of the East China Sea Basin,it is essential to advance research on anisotropic imaging technologies.This study responds to that need by integrating the reverse time migration method under a tilted transversely isotropic(TTI)medium model and applying it to the imaging of the Xihu depression.The imaging profiles based on the TTI medium can substantially improve the imaging accuracy and signal-to-noise ratio,effectively improve the imaging quality of the fault systems and mid-deep strata in the area,and provide new technical support and progress momentum for oil and gas exploration in the Xihu depression of the East China Sea.展开更多
Based on the two-dimensional(2D)three-component first-order velocity-stress equation,the high order staggered mesh finite difference numerical simulation method was used to simulate the elastic and viscoelastic tilted...Based on the two-dimensional(2D)three-component first-order velocity-stress equation,the high order staggered mesh finite difference numerical simulation method was used to simulate the elastic and viscoelastic tilted transversely isotropic(TTI)media.The perfect matched layer(PML)absorption boundary condition was selected to eliminate the boundary effect.The results show that:(①)Under the condition of fixed elastic parameters of elastic TTI medium,when the polarization angle and azimuth are 60°and 45°respectively,the degree of shear wave splitting is significantly greater than the angle of 0°;②The influence of viscoelasticity on TTI medium is mainly reflected in the amplitude.If the quality factor decreases,the attenuation of the seismic wave amplitude increases,causing the waveform to become wider and distorted.If the quality factor increases,the viscoelastic medium becomes closer to elastic medium;③For TTI medium with different polarization angle and azimuth angle in the upper and lower layers,the shear wave can multiple splits at the interface of medium.The symmetry of seismograms is affected by the polarization angle and azimuth angle of TTI medium;④Viscoelasticity has a great influence on reflected wave,transmitted wave and converted wave in the low-velocity model.When the viscoelasticity is strong,the weaker waves may not be shown.展开更多
基金the Major Science and Technology Project of CNOOC Limited Project‘Exploration Direction and Key Technology Study of Large and Medium-Sized Gas Fields in Haixi Sag,East China Sea’(No.KJZX-2023-0101)the China National Offshore Oil Corporation(CNOOC)during the‘14th Five-Year Plan’(No.KJGG2022-0104)+1 种基金the National Natural Science Foundation of China(Nos.42074138,42206195)the Science and Technology Innovation Project of the LaoShan Laboratory(No.2021WHZZB0703)。
文摘The East China Sea Shelf Basin,especially the Xihu depression in its northeastern region,has long been regarded as an important target area for oil and gas exploration in China.Since the development of the late Cretaceous,this region has experienced complex and multistage tectonic movements,such as extensional faulting and compressional inversion,forming its current unique geological structure pattern.As one of the largest Mesozoic–Cenozoic sedimentary basins offshore China,the East China Sea Shelf Basin not only contains abundant oil and gas resources but also occupies a key strategic position.In addition,it is gradually becoming an important base and strategic core area for China's oil and gas resource development.Although remarkable progress has been achieved in oil and gas exploration,seismic exploration in the Xihu depression still faces many challenges.Especially in deep target layers,weak seismic reflection energy,low signal-to-noise ratio,and poor wave group continuity seriously affect the efficiency and accuracy of oil and gas exploration.In addition,given the considerable influence of folds and faults in the East China Sea Xihu Basin,transverse anisotropy is widespread,which causes difficulty for conventional imaging technologies based on isotropic assumptions to achieve accurate imaging.Therefore,to address these challenges and meet the need for accurate imaging of complex structures in the Xihu depression of the East China Sea Basin,it is essential to advance research on anisotropic imaging technologies.This study responds to that need by integrating the reverse time migration method under a tilted transversely isotropic(TTI)medium model and applying it to the imaging of the Xihu depression.The imaging profiles based on the TTI medium can substantially improve the imaging accuracy and signal-to-noise ratio,effectively improve the imaging quality of the fault systems and mid-deep strata in the area,and provide new technical support and progress momentum for oil and gas exploration in the Xihu depression of the East China Sea.
基金the National Natural Science Foundation of China(Nos.41974048,41574078,41604039,41604102)the Guangxi Natural Science Foundation of China(Nos.2018GXNSFAA138059,2016GXNSFBA380082 and 2018GXNSFBA050005)+1 种基金Guangxi Science and Technology Base and Talent Project(Gui Kc AD19110057)Guangxi High School Junior Teachers Foundation Funding for capacity improvement projects(No.2019KY0264).
文摘Based on the two-dimensional(2D)three-component first-order velocity-stress equation,the high order staggered mesh finite difference numerical simulation method was used to simulate the elastic and viscoelastic tilted transversely isotropic(TTI)media.The perfect matched layer(PML)absorption boundary condition was selected to eliminate the boundary effect.The results show that:(①)Under the condition of fixed elastic parameters of elastic TTI medium,when the polarization angle and azimuth are 60°and 45°respectively,the degree of shear wave splitting is significantly greater than the angle of 0°;②The influence of viscoelasticity on TTI medium is mainly reflected in the amplitude.If the quality factor decreases,the attenuation of the seismic wave amplitude increases,causing the waveform to become wider and distorted.If the quality factor increases,the viscoelastic medium becomes closer to elastic medium;③For TTI medium with different polarization angle and azimuth angle in the upper and lower layers,the shear wave can multiple splits at the interface of medium.The symmetry of seismograms is affected by the polarization angle and azimuth angle of TTI medium;④Viscoelasticity has a great influence on reflected wave,transmitted wave and converted wave in the low-velocity model.When the viscoelasticity is strong,the weaker waves may not be shown.
