Fat ray traveltime tomographic imaging based on multiple frequencies’ combination
Yang Xuelin1,2, Lin Zhenchun1, Yin Zheng1,3, Zhang Kai1, Sang Yunyun4
1. School of Geosciences, China University of Petroleum (East China), Qingdao, Shandong 266580, China;
2. Geophysical Technology Research Center, BGP Inc., CNPC, Zhuozhou, Hebei 072751, China;
3. Reservoir Research Center, BGP Inc., CNPC, Zhuozhou, Hebei 072751, China;
4. Renqiu Branch, GRI, BGP Inc., CNPC, Renqiu, Hebei 062552, China
Abstract：In conventional seismic imaging experiments, traveltime tomography based on ray theory plays an important role in gaining the velocity construction. However, the traveltime tomography relies on infinite frequency assumption which results in serious ill-conditioned matrix and has negative inference on the result. We propose the fat ray traveltime tomography based on first Fresnel zone and multiple frequencies' combination. We broaden the ray by first Fresnel zone and modify the Frechet function by weighting influence factors to resolve the instability caused by ill-conditioned matrix. Meanwhile, we enhance the resolution and precision by combining multiple frequencies. Our method improves the efficiency by avoiding the calculation of ray path. The inverted result proves that our method has a higher resolution and accuracy than the ray theory tomography.
