SEAM contracted with Nexus Geosciences Inc. (NGI), now part of WesternGeco, to conduct quality control (QC) evaluation of all data delivered by the simulation vendor. The steps in the QC process were developed by the Execution Committee and approved by the Management Committee (see Appendix A, “Description of QC Services”). The data flow diagram in Figure 4 of in Chapter 1 illustrates the relationships of all the vendors, SEAM committees, and individuals involved. The QC vendor received compressed data from the simulation vendor on USB disk. The data were decompressed, and the QC process was initiated. Once data were passed through the QC process, the USB disks were sent to the storage vendor. During the decompression, traces that comprise the classic data sets were extracted. These were sent to Stew Levin, who stored and compiled these data and compressed them for long-term storage.
The quality-assurance protocol was designed to provide a thorough but timely assessment of data quality and model performance and to identify potential problems for correction. The procedure contains a number of steps to
Test quality of the numerical simulations, including evaluation for excessive amplitudes that may indicate numerical problems.
Ensure shots and traces are in their expected and correct locations.
Prepare fold maps.
Ensure no corruption of data during compression and loading of storage media that were used to transport data between simulation, QC, and data storage vendors.
Extract zero-offset traces, depth-migrate them, and overlay on the model. Raw zero.
Figures & Tables
SEAM Phase I: Challenges of Subsalt Imaging in Tertiary Basins, with Emphasis on Deepwater Gulf of Mexico
“SEAM is a collaborative industrial research effort dedicated to largescale, geophysical numerical simulation projects. The projects are designed to provide the geosciences exploration community with earth models and simulated data that represent significant geophysical challenges of high business value to the petroleum resource industry. The Phase I project produced a deepwater subsalt earth model designed to capture as much physics and realism as possible in a 3D model that was relevant to oil and gas exploration. The 3D model covers a 40 õ 35 õ 15 km area and includes a complex salt intrusive in a folded Tertiary basin. The primary deliverable was the seismic data set of variable density acoustic simulations consisting of 200 TB of uncompressed traces for over 60,000 shots. Also delivered to the participants were several smaller compressed subsets of these data (“classic” data sets) intended for easier handling, simpler distribution to third parties, and easier comparison of imaging tests results. This report covers how the prime objectives of Phase I were met. Details are outlined in chapters on Model Development, Numerical Design and Vendor Qualification, Acquisition Design, Production Simulations, Quality Control, and Data Storage and Distribution.”