1Chevron USA Production Company
2Chevron Petroleum Technology Company
Structural interpretation around salt domes is often complicated by imaging problems and the presence of steeply dipping seismic reflectors and faults of varying orientations. Interpretation using only seismic amplitude and/or amplitude difference (Edge) cubes is time consuming and can often be misleading. Properly processed multi-attribute cubes which incorporate both the amplitude and the Edge information contain the data necessary to map faults and related stratal geometries and allow the interpreter to make more realistic structural interpretations. In the Main Pass 299 area we have used seismic Edge detection technology and a workflow that utilizes multiple properties of the seismic data to help resolve small scale faulting adjacent to salt and define untested fault blocks. Significant business impacts of the application of this workflow in the Main Pass 299 field include; reduction of interpretation cycle time, an increased confidence in the structural interpretation and the delineation of potential unbooked reserves in an untested fault block.
Three workstation applications for combining seismic attributes into a single visual presentation were compared. In-house 3D interpretation software combines seismic attributes by pixel dithering or a spatial interleaving of the two input cubes. This process results in decreased resolution of each of the attributes being combined, but provides the ability to interactively change the weighting of each attribute within the multi-attribute cube. Combination of seismic attributes at full resolution using the properties of color (intensity, hue and saturation) was accomplished with proprietary software. Combination of seismic attributes with commercially available 3D visualization and image processing software (VoxelGeo) allows the user real time interactive control over attribute weighting at full resolution and was used to optimize attribute weighting parameters and produce an optimum multi-attribute interpretation product for structural interpretation.
A structural/stratigraphic interpretation workflow utilizing single (amplitude) and the multi-attribute (amplitude and amplitude difference) seismic data cube, 3D visualization software and conventional 2D mapping applications was used for seismic interpretation, map generation and prospect evaluation.
Our work has shown that optimizing Edge processing parameters and color balancing of seismic attributes in multi-attribute cubes has a significant effect on imaging faults and therefore interpreting complex structure around salt domes. In Edge processing the Main Pass 299 data we used dip steering and an improved difference algorithm that produces higher resolution edges from the input volume of seismic data. The result is a sharper definition and discrimination of individual faults in steeply dipping areas adjacent to the salt dome where remaining development/delineation drill potential exists.
AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas