SEG/EAEG 3-D modeling project: 2nd update

Abstract

The first update for the SEG/EAEG 3-D Modeling Project appeared in the February issue of TLE and the March issue of First Break. Our goal is to design salt and overthrust 3-D models and then simulate realistic 3-D surveys based on those models. Given the project's significance and scope, we plan frequent progress reports. In conjunction with this goal and to solicit input, we have made recent presentations at SEG Cairo, the SEG/EAEG Summer Research Workshop in The Netherlands, the Stanford Exploration Project, and the Center for Wave-Phenomena at the Colorado School of Mines.The committee expects to freeze the models based on feedback from the SEG and EAEG membership. They will then be available to the general public, most probably via CD-ROM.We are soliciting commercial entities to be considered as the repository of the models and simulation results (perhaps one in Europe and one in North America). Progress reports of the project working groups (salt model, overthrust model, and computations and algorithms) follow. Salt ModelThe first version has been constructed and placed in the public domain, accessible via Internet, in GOCAD format. This version, primarily describing the model's structural components, measures 90 000 ft in x,y and 24 000 ft in z. Figure 1 shows a 3-D visualization of the major components.The velocities surrounding the salt body are typical of Gulf of Mexico sedseismic response and the computational iments and described by compaction cost of the synthetic generation. Prelimgradients based on K-V, curves (K, the inary results on a 2-D cross section gradient, varies spatially and V, is the using the spike technique have been obinitial velocity) and a geopressure surtained. Figure 3a shows the velocity face. However, a constant density conprofile and Figure 3b the resulting 2-D straint has been placed due to the finite zero offset simulation. These prelimidifference software employed and nary results seem to indicate that the available computational resources. This spike technique is adequate; however, constant density assumption and simple more testing is required. velocity gradient results in no seismicIn the meantime, a 3-D velocity grid, reflectivity in the sediments surroundemploying the spike technique, has ing the salt. Two techniques (Figure 2) been generated and provided to US Naare being investigated via 2-D finite diftional Laboratories for testing of the 3-D ference modeling. The first ("spike") finite-difference software. increases the velocity of the finite dif-A second area of considerable invesference grid cell nearest each layer tigation is how to perform 3-D finite boundary by a certain percentage. The difference simulation on the salt model second ("block") alternately increases within the current resources offered by and decreases the velocity of the K-V, the US Department of Energy. A first function for each successive layer. estimate on the required computing reSince these techniques can vary the seissources far exceeded the existing budmic response of the model, two-dimeng...

High Resolution/High Fidelity Seismic Imaging and Parameter Estimation for Geological Structure and Material Characterization

“…We exemplify the method with illumination, including DI and ADR, for downgoing waves in the 2D SEG/EAGE salt model (Aminzadeh et al, 1994;Aminzadeh et al, 1995), turning waves in a v(z) model, and reflected waves in a two-layer model.…”

“…Then the new implementation is described. We exemplify the method with the GDF and the LEF decomposition in 2D SEG/EAGE salt model (Aminzadeh et al, 1994;Aminzadeh et al, 1995) and compare the results with those from the original method. We also discuss the possible factors causing the difference in the results by the GDF and the LEF decomposition.…”

“…We exemplify the new implementation of LAD acquisition aperture correction with 2D SEG/EAGE salt model (X Figure 8.2) data set (Aminzadeh et al, 1994;Aminzadeh et al, 1995). The whole acquisition system of this model consists of 325 shots with 176 left-side trailing receivers for each shot and the shot and receiver intervals are 160 and 80 feet respectively.…”

Salvo: Seismic imaging software for complex geologies

“…encoding parm Chirp encoding requires a stretching parameter which may vary between the approximate range [2][3][4][5][6][7][8][9][10]. Linear phase encoding requires the desired time shift between the shots, -to,in seconds.…”

“…For the Phase C3 data set, Paul Docherty of Fairfield Industries should be contacted for copies of the SEGY tapes. The data for the Salt model was generated with a forward modeling code from IFP [2] which subsequently was parallelized by several national laboratories: Sandia National Laboratories [25], Oak Ridge National Laboratories, Los Alamos National Laboratories, and Lawrence Livermore National Laboratories. The velocity model used in the forward modeling is shown in Figure 38, and is comprised of 676 by 676 by 210 grid points with a grid spacing of 20 m in each direction.…”