A generalized view on normal moveout
While in the past, in the context of stacking, traveltime moveout was only formulated in individual common-midpoint (CMP) gathers, multi-parameter stacking utilizes normal moveout (NMO) approximations, which span several neighboring CMPs. Multi-parameter expressions such as the common reflection sur...
| Egile Nagusiak: | , |
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| Formatua: | Journal article |
| Argitaratua: |
Society of Exploration Geophysicists
2017
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| _version_ | 1826279191215079424 |
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| author | Schwarz, B Gajewski, D |
| author_facet | Schwarz, B Gajewski, D |
| author_sort | Schwarz, B |
| collection | OXFORD |
| description | While in the past, in the context of stacking, traveltime moveout was only formulated in individual common-midpoint (CMP) gathers, multi-parameter stacking utilizes normal moveout (NMO) approximations, which span several neighboring CMPs. Multi-parameter expressions such as the common reflection surface (CRS) or multifocusing are parameterized in terms of local slopes and curvatures of emerging wavefronts rather than effective velocities, which makes these approaches appear conceptually different from conventional velocity analysis. As a consequence, the unifying nature of multi-parameter NMO is still not well appreciated. In addition, CRS and multifocusing show distinctly different behavior in that they respond differently to both, overburden heterogeneity and curvature of the target interface, and either are or are not susceptible to moveout stretch. In this work we seek to demystify the wavefront picture by demonstrating that the conventional and multi-dimensional NMO operators can conveniently be derived from the same auxiliary straight-ray geometry, either representing the optical projection or formulated in an effective replacement medium. Following the early work of de Bazelaire, we suggest a simple transformation between both domains and introduce generalized dual representations of the hyperbolic CRS, multifocusing, and the two recently introduced double-square-root expressions implicit CRS and nonhyperbolic CRS. In addition, we discuss a generalized finite-offset NMO expression that can likewise be applied to active-source diffraction data and passive seismic events. Synthetic examples suggest unification, conveniently explain the origin of moveout stretch and show that the joint use of different NMO approximations offers new insight into the character and origin of different wavefield components. |
| first_indexed | 2024-03-06T23:55:05Z |
| format | Journal article |
| id | oxford-uuid:73ee3714-97c5-4e12-90ba-e56c99254980 |
| institution | University of Oxford |
| last_indexed | 2024-03-06T23:55:05Z |
| publishDate | 2017 |
| publisher | Society of Exploration Geophysicists |
| record_format | dspace |
| spelling | oxford-uuid:73ee3714-97c5-4e12-90ba-e56c992549802022-03-26T19:59:35ZA generalized view on normal moveoutJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:73ee3714-97c5-4e12-90ba-e56c99254980Symplectic Elements at OxfordSociety of Exploration Geophysicists2017Schwarz, BGajewski, DWhile in the past, in the context of stacking, traveltime moveout was only formulated in individual common-midpoint (CMP) gathers, multi-parameter stacking utilizes normal moveout (NMO) approximations, which span several neighboring CMPs. Multi-parameter expressions such as the common reflection surface (CRS) or multifocusing are parameterized in terms of local slopes and curvatures of emerging wavefronts rather than effective velocities, which makes these approaches appear conceptually different from conventional velocity analysis. As a consequence, the unifying nature of multi-parameter NMO is still not well appreciated. In addition, CRS and multifocusing show distinctly different behavior in that they respond differently to both, overburden heterogeneity and curvature of the target interface, and either are or are not susceptible to moveout stretch. In this work we seek to demystify the wavefront picture by demonstrating that the conventional and multi-dimensional NMO operators can conveniently be derived from the same auxiliary straight-ray geometry, either representing the optical projection or formulated in an effective replacement medium. Following the early work of de Bazelaire, we suggest a simple transformation between both domains and introduce generalized dual representations of the hyperbolic CRS, multifocusing, and the two recently introduced double-square-root expressions implicit CRS and nonhyperbolic CRS. In addition, we discuss a generalized finite-offset NMO expression that can likewise be applied to active-source diffraction data and passive seismic events. Synthetic examples suggest unification, conveniently explain the origin of moveout stretch and show that the joint use of different NMO approximations offers new insight into the character and origin of different wavefield components. |
| spellingShingle | Schwarz, B Gajewski, D A generalized view on normal moveout |
| title | A generalized view on normal moveout |
| title_full | A generalized view on normal moveout |
| title_fullStr | A generalized view on normal moveout |
| title_full_unstemmed | A generalized view on normal moveout |
| title_short | A generalized view on normal moveout |
| title_sort | generalized view on normal moveout |
| work_keys_str_mv | AT schwarzb ageneralizedviewonnormalmoveout AT gajewskid ageneralizedviewonnormalmoveout AT schwarzb generalizedviewonnormalmoveout AT gajewskid generalizedviewonnormalmoveout |