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Collaborating Authors
Results
On seismic deghosting using Green’s theorem
Amundsen, Lasse (Statoil Research Centre, The Norwegian University of Science and Technology) | Reitan, Arne (Arne Reitan Consulting) | Weglein, Arthur B. (University of Houston) | Ursin, Bjørn (Universidade Federal da Bahia, The Norwegian University of Science and Technology)
ABSTRACT We have examined theoretically how receiver-side deghosting of pressure measurements can be derived from the Green’s theorem method. We split the Green’s function that obeys Dirichlet boundary conditions on the sea surface and at the receiver plane into two contributions: the first emitting energy downward only from its source location and the other emitting energy only upward. Using the normal derivative of the source-side downgoing Green’s function in the Green’s theorem evaluation over the receiver plane, the upgoing part of the pressure field is predicted. This is the receiver-side deghosted field. By inserting the source-side upgoing normal derivative Green’s function in Green’s theorem, its evaluation over the receiver plane predicts the downgoing part of the pressure field. For a plane horizontal receiver surface, the required Green’s function can be derived using the image series expansion method. To display the fundamental frequencies of this Green’s function, we have applied a Fourier series expansion of the Green’s function. Our theory gives a new understanding of and generalizes and simplifies previously published theories on Green’s theorem-based receiver-side deghosting of pressure wavefields.
On seismic deghosting by spatial deconvolution
Amundsen, Lasse (Statoil Research Centre, The Norwegian University of Science and Technology) | Zhou, Hongbo (Statoil Gulf Services Inc.) | Reitan, Arne | Weglein, Arthur B. (University of Houston)
ABSTRACT Receiver-side deghosting can be derived and implemented in the frequency domain as spatial deterministic deconvolution of marine pressure recordings. The deghosting/deconvolution operator is found analytically as the inverse Fourier transform of the wavenumber-domain wave equation deghosting function. For a sea surface reflection coefficient of , the wavenumber-domain deghosting function has well-known poles at fundamental frequencies equal to an integer multiple of a function of the receiver depth and the plane-wave dip angle relative to the depth axis. The first singularity is always at 0 Hz. The spatial deghosting operator has singularities at fundamental frequencies equal to an integer multiple of a function of the receiver depth, independent of its lateral coordinates. The first singularity is again at 0 Hz. In addition, the deghosting operator that is applied to 3D data has singularity when its lateral coordinate is zero. A simple numerical example demonstrates the method.
- Europe > Norway (0.29)
- North America > United States > Texas (0.29)
ABSTRACT The recent interest in broadband seismic technology has spurred research into new and improved seismic deghosting solutions. One starting point for deriving deghosting methods is the representation theorem, which is an integral representation for the wave equation. Recent research results show that by using Green’s functions with Dirichlet boundary conditions in the representation theorem, source-side deghosting of already receiver-side deghosted wavefields can be achieved. We found that the choice of Green’s functions with Neumann boundary conditions on the sea surface and the plane that contains the sources leads to an identical but simpler solution with fewer processing steps. In addition, we found that pressure data can be receiver-side deghosted by introducing Green’s functions with Dirichlet boundary conditions on the sea surface and the plane containing the receivers into a modified representation theorem. The deghosting methods derived from the representation theorem are wave-theoretic algorithms defined in the frequency-space domain and can accommodate streamers of any shape (e.g., slanted). Our theoretical analysis of deghosting is performed in the frequency-wavenumber domain where analytical deghosting solutions are well known and thus are available for verifying the solutions. A simple numerical example can be used to show how source-side deghosting can be performed in the space domain by convolving data with Green’s functions.
- Europe (0.68)
- North America > United States > Texas (0.28)
First Field Data Examples of Inverse Scattering Series Direct Depth Imaging Without the Velocity Model
Weglein, Arthur B. (M-OSRP) | Liu, Fang (M-OSRP) | Li, Xu (M-OSRP) | Terenghi, Paolo (M-OSRP) | Mayhan, James D. (M-OSRP) | Wang, Zhiqiang (M-OSRP) | Liang, Hong (M-OSRP) | Tang, Lin (M-OSRP) | Hsu, Shih-Ying (M-OSRP) | Kragh, Ed (Schlumberger) | Mispel, Joachim (Statoil ASA) | Amundsen, Lasse (Statoil ASA)
Summary In Weglein et al. (2010) an update and status report were provided on the progress on the inverse scattering series (ISS) direct depth imaging without the velocity model. In that report, results on synthetics with sufficient realism indicated that field data tests were warranted. This paper documents those first field data tests. These first early tests are encouraging and indicate that ISS direct depth imaging on field data is possible. The next steps on the road between viable and providing relevant and differential added value to the seismic tool-box are described and discussed.
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.64)