Fu, Qiang (M-OSRP, Physics Department, University of Houston) | Zou, Yanglei (M-OSRP, Physics Department, University of Houston) | Wu, Jing (M-OSRP, Physics Department, University of Houston) | Weglein, Arthur B. (M-OSRP, Physics Department, University of Houston)
The Inverse Scattering Series (ISS) internal multiple attenuation algorithm can predict the exact time and approximate amplitude of every internal multiple at all offsets at once. This algorithm does not require any subsurface information and it is model-type independent. When the primaries and multiples are isolated, the ISS internal multiple attenuation algorithm plus energy minimization adaptive subtraction can effectively eliminate internal multiples independent of the the medium model type (e.g. acoustic, elastic, anisotropic, inelastic, etc.). However, when internal multiples are proximal to and/or interfering with a primary, the energy-minimization adaptive subtraction can fail. In proximal /interfering cases the ISS elimination algorithm is needed for predicting the exact time and exact amplitude of multiples, and it would not depend on the energy minimization criteria to fill the gap between attenuating and eliminating the internal multiple. Thus M-OSRP proposed developing ISS internal multiple elimination algorithm to accommodate these proximal/interfering cases. We have an interest in examining the issue of the elimination of interfering internal multiples for increasingly realistic subsurface circumstances. We also recognize the benefit of studying each step of added realism and complexity in isolation. Absorption/dispersion can have a very significant impact on amplitude, often more significant than the acoustic/elastic differences. There is a line of research in the ISS initiative that extends the development and analysis to the absorptive/dispersive world by studying an acoustic absorptive medium. For example, Innanen and Weglein (2003, 2005); Innanen and Lira (2008, 2010); Wu and Weglein (2014). This paper follows that line of contributions and extends ISS internal multiple elimination to absorptive/dispersive acoustic medium, which is the simplest world with an absorptive/dispersive property. We test the current ISS internal multiple elimination algorithm on synthetic data (P-only events) from attenuating medium both analytically and numerically. The analysis and results of the tests show that the current elimination algorithm predicts P-only internal multiple in an absorptive/dispersive medium with both the exact time and amplitude if the absorption/dispersion (finite Q) is only located beneath the generator (which is where the the downward reflection occurs) of the first-order internal multiple, without knowing the medium and its absorptive/dispersive properties. Under this type of circumstances the current ISS internal multiple elimination algorithm is fully effective in predicting accurate P-only internal multiples in an absorptive/dispersive medium. That is positive news for the exploration plays where absorption is only significant below the major internal multiple generators. For instance, that can be the situation for a single absorptive salt body. In this case the major internal multiple generator is often either the water bottom or the top of the salt body and the major attenuation happens within the salt body. Thus the absorption is only existing below the generator, the current acoustic based elimination algorithm is sufficient for predicting an effective P-only internal multiple in this type of exploration play.
Presentation Date: Monday, October 15, 2018
Start Time: 1:50:00 PM
Location: 211A (Anaheim Convention Center)
Presentation Type: Oral