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|Type:||Artigo de periódico|
|Title:||Attaching true amplitudes to kinematically migrated images|
|Abstract:||True-amplitude depth migration means that the migration amplitudes of primary reflections are free from the geometrical-spreading losses. When other main factors that affect the amplitude or at least their variations within the studied data set (such as transmission losses across interfaces, attenuation, etc.) can be neglected, or accounted for, true amplitudes become better approximations of angle-dependent reflection coefficients, In this way, they can be used for reliable AVO/AVA studies. Full true-amplitude depth migration algorithms (e.g., Kirchhoff weighted stacks) are generally very expensive and time consuming. An alternative to obtain true-amplitude migration results using a less expensive method is considered in this work, We propose to pick amplitudes within a common reflection point gather in the raw data and compensate them for geometrical spreading using ray tracing in order to get true reflectivity variation versus offset. The ray tracing requires a velocity model that well approximates the main features of the subsurface, say the location and geometry of key interfaces. This model is supposed to be constructed after simpler (kinematical) depth migration procedures. Using that model, the arrival times and geometrical-spreading factors for selected events are evaluated and applied to retrieve true amplitudes reflection from target reflectors. In this paper we apply this scheme to a synthetic data set obtained by finite-differences modelling. For simplicity, we use as a first approach, the true velocity field for the kinematic and dynamic ray tracing. In real situations (out of scope in this work), the velocity model should be the one obtained after integration of all available information (such as well logs and geological interpretation) into some kinematic image software.|
dynamic ray tracing
|Citation:||Journal Of Seismic Exploration. Geophysical Press, v. 10, n. 41699, n. 149, n. 164, 2001.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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