Gaussian beam migration （GBM） is an effec- tive and robust depth seismic imaging method, which overcomes the disadvantage of Kirchhoff migration in imaging multiple arrivals and has no steep-dip limitation of one-wa...Gaussian beam migration （GBM） is an effec- tive and robust depth seismic imaging method, which overcomes the disadvantage of Kirchhoff migration in imaging multiple arrivals and has no steep-dip limitation of one-way wave equation migration. However, its imaging quality depends on the initial beam parameters, which can make the beam width increase and wave-front spread with the propagation of the central ray, resulting in poor migration accuracy at depth, especially for exploration areas with complex geological structures. To address this problem, we present an adaptive focused beam method for shot-domain prestack depth migration. Using the infor- mation of the input smooth velocity field, we first derive an adaptive focused parameter, which makes a seismic beam focused along the whole central ray to enhance the wave- field construction accuracy in both the shallow and deep regions. Then we introduce this parameter into the GBM, which not only improves imaging quality of deep reflectors but also makes the shallow small-scale geological struc- tures well-defined. As well, using the amplitude-preserved extrapolation operator and deconvolution imaging condi- tion, the concept of amplitude-preserved imaging has been included in our method. Typical numerical examples and the field data processing results demonstrate the validity and adaptability of our method.展开更多
Dielectric degradation typically originates from local defects.The resulting electric field concentration accelerates defect growth.Suppressing field distortion arising from such local weaknesses has long been a major...Dielectric degradation typically originates from local defects.The resulting electric field concentration accelerates defect growth.Suppressing field distortion arising from such local weaknesses has long been a major challenge in electrical insulation.In this work,we incorporated the voltage stabiliser anthrone(ET)into cross-linked polyethylene(XLPE).This design enables fielddriven adaptive migration and charge trapping,thereby dynamically regulating local electric fields.Space charge analysis reveals that ET captures charge and creates a reverse electric field.This process inhibits charge injection and transport,significantly reduces internal field distortion and results in a negative electric field coefficient effect.Notably,at 110 kV/mm the distortion ratio decreases from 118.6%in XLPE to only 0.05%in ET/XLPE,a reduction by more than 2000 times.These findings highlight the critical role of voltage stabilisers in enhancing dielectric reliability.展开更多
文摘Gaussian beam migration （GBM） is an effec- tive and robust depth seismic imaging method, which overcomes the disadvantage of Kirchhoff migration in imaging multiple arrivals and has no steep-dip limitation of one-way wave equation migration. However, its imaging quality depends on the initial beam parameters, which can make the beam width increase and wave-front spread with the propagation of the central ray, resulting in poor migration accuracy at depth, especially for exploration areas with complex geological structures. To address this problem, we present an adaptive focused beam method for shot-domain prestack depth migration. Using the infor- mation of the input smooth velocity field, we first derive an adaptive focused parameter, which makes a seismic beam focused along the whole central ray to enhance the wave- field construction accuracy in both the shallow and deep regions. Then we introduce this parameter into the GBM, which not only improves imaging quality of deep reflectors but also makes the shallow small-scale geological struc- tures well-defined. As well, using the amplitude-preserved extrapolation operator and deconvolution imaging condi- tion, the concept of amplitude-preserved imaging has been included in our method. Typical numerical examples and the field data processing results demonstrate the validity and adaptability of our method.
基金supported by the National Natural Science Foundation of China(Grant 52037009).
文摘Dielectric degradation typically originates from local defects.The resulting electric field concentration accelerates defect growth.Suppressing field distortion arising from such local weaknesses has long been a major challenge in electrical insulation.In this work,we incorporated the voltage stabiliser anthrone(ET)into cross-linked polyethylene(XLPE).This design enables fielddriven adaptive migration and charge trapping,thereby dynamically regulating local electric fields.Space charge analysis reveals that ET captures charge and creates a reverse electric field.This process inhibits charge injection and transport,significantly reduces internal field distortion and results in a negative electric field coefficient effect.Notably,at 110 kV/mm the distortion ratio decreases from 118.6%in XLPE to only 0.05%in ET/XLPE,a reduction by more than 2000 times.These findings highlight the critical role of voltage stabilisers in enhancing dielectric reliability.
