Extending the Inverse Scattering Series Free-Surface Multiple Elimination and Internal Multiple Attenuation Algorithms by Incorporating the Source Wavelet and Radiation Pattern: Examining and Evaluating the Benefit and Added-Value

As the petroleum industry moves to more complex and challenging offshore and onshore plays, untangling multiples and primaries becomes more challenging. This dissertation is part of a comprehensive strategy to address the outstanding and pressing challenges in exploration seismology. To improve the effectiveness of the inverse scattering series (ISS) methods, the current ISS demultiple methods are modified and extended from an isotropic point source to a general source array by incorporating the source wavelet and radiation pattern.

In this dissertation, three projects are discussed and contributed. First, several Green's theorem preprocessing methods are provided. They can in practice provide all the prerequisites (reference wave removal, an estimation of source wavelet and radiation pattern, and deghosting) required by ISS methods. Numerical examples for finding the source wavelet and radiation pattern and deghosting are shown by using Green's theorem methods. Second, the effects of satisfying and not satisfying the prerequisites of the ISS algorithms are exemplified. To improve the experimental description, the current ISS free-surface multiple elimination algorithm is extended and modified from the isotropic point source to accommodate a general source array with a radiation pattern. In tests using synthetic point-source data, the current ISS free-surface elimination algorithm can predict the free-surface multiples accurately and remove them from the data through a simple subtraction without the need for adaptive subtraction. In tests using synthetic source-array data, the extended free-surface multiple elimination algorithm (in principle) has the ability to predict precisely the free-surface multiples when the source corresponds to an array (or a point source has radiation pattern). Third, to enhance the fidelity of the amplitude and phase predictions of internal multiples, the ISS internal multiple attenuation algorithm is also modified and extended by incorporating the source wavelet and radiation pattern. The tests on synthetic data show that the extended algorithm can improve the amplitude and phase prediction of internal multiples.

In summary, this dissertation contributes to our seismic capability by adding the realism and more complete physics of a source that has a radiation pattern into the ISS free-surface multiple elimination and internal multiple attenuation algorithms.