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|Title: ||Inverse-ray imaging of a 3D homogeneous layer based on common-shot gathers of oblique profiles|
|Authors: ||Tan-Kin Wang;Kai-Ming Chang|
|Contributors: ||NTOU:Institute of Applied Geosciences|
|Keywords: ||Apparent dip;Migration;Multi-channel seismic;Ray geometry;Reflector;Travel time|
|Issue Date: ||2011-10-20T08:19:12Z
|Publisher: ||TERR ATMOS OCEAN|
|Abstract: ||abstract:Imaging of 3D structural interfaces through reflected rays shooting from common-shot gathers is presented in this paper. First, by fitting the reflected arrivals picked from common-shot gathers, we calculate apparent dips and the shortest distances between sources and reflectors along two profiles. Then, based on the geometry of the profiles and a planar reflector, a unit normal vector of the reflector is determined from the apparent dips and the azimuths of two oblique profiles. A special case, when apparent dips are zero along two parallel profiles, for determining the reflector normal is also investigated. We propose three criteria to ensure the selected travel-times along two profiles resulting from the same planar reflector. These are that firstly, the same shortest distance from sources to the reflector is utilized; and secondly, we want to ensure the same normal of the reflector, and finally, the same ray distance.
Prestack inverse-rays developed in this paper are applied to image the bathymetry of the Hoping Basin in the southernmost Ryukyu subduction zone and the fourth layer of the SEG/EAEG over-thrust model. Based on common-shot gathers along seven oblique profiles in the Hoping Basin, most of the reflection points are well imaged through inverse rays except when variation of the interface depth exceeds 300 m across profiles with spacing greater than about 20 km. Inverse-ray imaging of the over-thrust model
Inverse-ray imaging of 3D structures from 2D multi-channel seismic profiles is demonstrated if a pseudo-3D structure (a planar reflector) exists between profiles or if at least two profiles are within a Fresnel zone. Although this technique deals with a single-layered problem currently, it is fundamentally important when we extend it to image inhomogeneous multilayered media.
|Relation: ||16, pp.547-561|
|Appears in Collections:||[應用地球科學研究所] 期刊論文|
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