OUR SERVICES

The successful execution of every depth imaging project lies at the core of our services. Our services include the three technologies required for successful execution of every depth imaging project: model building, prestack depth migration and data analysis.

The quality of the final depth migrated volume is only as good as the velocity model constructed during the model building phase. We devote the majority of the depth imaging process to building an accurate velocity model. Our workflow is based on repeated iterations of full volume prestack depth migration where at each iteration the model is updated using the results from the prior depth migrated volume. Every model building iteration is performed using full volume prestack depth migrated data.

Using GoCad technology for structural modeling, we are able to create detailed interpretations of major layer boundaries, construct  model surfaces, combine surfaces to form geological bodies, and then apply topology to assign velocity functions to the different compartments of the model.

Velocity analysis is done using two tools: reflection tomography and prestack depth migration scans. We are using the scan technique to obtain the initial velocity model, followed by reflection tomography to add details to the velocity model. Combination of the two tools enables us to develop accurate velocity models to be used in prestack depth migration.

Our model building tools are suitable for construction of GOM type models with smooth sedimentary velocity functions and detailed salt bodies, as well as layer based models needed for imaging of overthrust geology.

We offer a series of prestack depth migration algorithms, both ray trace and wave equation based. These include a wavefront reconstruction Kirchhoff summation algorithm, common shot downward extrapolation wave equation algorithm, and common shot two-way wave equation (i.e. RTM) algorithm.

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The appropriate algorithm is selected based on the geological setting and the imaging objective of the project. In most cases we use repeated iterations of full volume Kirchhoff summation algorithm for the major part of model building, one-way wave equation for model validation, and conclude with two final runs, one using two-way wave equation RTM and one using Kirchhoff summation algorithms.

Our prestack depth migration algorithms are implemented in the common shot domain. No data decimation or conditioning is applied prior to prestack depth migration. All prestack depth migrations output fully migrated volumes with image gathers output at each migrated bin.

Anisotropic model building and prestack depth migration

We also offer full anisotropic model building and prestack depth migration. This is done as part of both our Kirchhoff summation as well as RTM workflows. The objective of anisotropic model building and imaging is to construct a depth migrated image that will better match observed well data. The anisotropic depth migrated volume will image events in different depth and horizontal position, compared to an isotropic depth migrated volume. Mapping of exploration structures using an anisotropic PreSDM volume will result in a more accurate structural depth map.

We are building and supplying a 3-parameter model as input to our anisotropic prestack depth migration. The three parameters are vertical velocity, delta volume and epsilon volume. Our model building velocity analysis tools use both PreSDM scan as well as tomographic inversion for analysis and optimization of the three anisotropic parameters.

Our anisotropic depth imaging workflow is routinely used to produce reliable depth migrated volumes on which structural mapping can be directly applied.

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An integral part of depth imaging is the use of simulation to assist in understanding field acquired and depth imaged seismic data. We are offering full wave equation simulation as part of our services. Simulation is done to help in investigations of

• Seismic illumination
• Imaging artifacts
• Acquisition design

Seismic illumination
Illumination analysis is routinely done in order to interpret and identify areas of low illumination. A typical application is to investigate areas of low illumination below large salt bodies. Our illumination services are based on application of the full wave equation. No smoothing of the velocity field is done prior to simulation. The workflow for illumination analysis includes construction of a detailed model, simulation using wave equation algorithms, imaging using various depth migration algorithms and finally extraction of illumination surfaces from the migrated volumes. The illumination surfaces are compared to amplitude maps extracted from the field data depth migrated volumes.

Imaging artifacts
When applying prestack depth migration, the objective is to produce depth migrated volumes that include reflections from geological layer boundaries. However prestack depth migrated volumes include coherent noise as well. Coherent noise can be a result of migrating multiples, migration operator swings in areas of low illumination or seismic data recorded along complex wave paths that were not migrated correctly. Using wave equation simulation and imaging, we are producing a depth migrated volume where the input model is known. With that, we can differentiate real geological reflections from noise artifacts and provide a tool to assist in the interpretation of the real data. 

Acquisition design
Modern marine acquisition design can be optimized by the use of 3D wave equation simulation. With our 3D two-way wave equation simulation algorithms, we are offering simulation based acquisition design. This service includes generation of a detailed 3D model, simulation and recording of a dataset over a large grid, and then imaging using subsets of the recorded dataset. With this workflow, key acquisition parameters can be optimized such as cable length, azimuth distribution, number of gun and cable boats as well as the optimal sailing directions. More than that, as part of wave equation simulation for acquisition design, a simulated dataset is generated and delivered to our clients.