Data rejuvenation and new acquisition campaigns extend and complement the existing data coverage.

Challenges of Imaging the Near Surface Overcome with Innovative Workflows

For over 10 years, TGS has built a comprehensive and contiguous data library in the Norwegian Sea and has employed a wide range of technologies and workflows to address imaging challenges for various targets. 

Although the overburden may seem simple, high compaction, uplifting, and erosion have resulted in a near-surface characterized by high impedance contrasts, rough surfaces, a complex velocity regime, and anisotropy. For example, the water bottom is highly reflective and generates abundant multiples along with other shallow events. Small features, such as trenches and iceberg scars, while very interesting, cause strong noise and multiples, which can affect the imaging of both shallow and deeper targets. 

The slider below demonstrates the high-grading of data, initially reprocessed in 2016, where additional multiple workflows were applied before seamlessly merging it with a newly acquired and processed dataset in 2019 and a final Kirchoff prestack depth migration. The improvements can be as much attributed to technological advancements as to knowledge building and transfer. 

Before Image After Image
Before
After
A Norwegian Sea dataset reprocessed in 2016 (left) was improved by merging it with a 2019 dataset and applying an additional demultiple workflow (right).

TGS imaging workflows are applied dynamically to respond to the change in geology across the region. For example, processing can be carried at 2 ms to retain maximum resolution in the shallow Jurassic prospects of the eastern terraces. Likewise, additional demultiple and denoise workflows are required in the thick Cretaceous sequence of the western basins, where highly faulted mud-rich packages are nearly transparent on reflectivity sections and where AVO class II protects require appropriate handling of the prestack amplitude and phase information.

Multi-Azimuth Resolves Fault Shadow Areas 

More recently, multi-azimuth solutions have demonstrated their value for imaging and velocity model building (including FWI), particularly in highly faulted basins where dip shooting is typically favored, leaving fault shadow areas due to the lack of illumination. The slider below illustrates the significant improvement obtained at target reflectors and fault definitions from a single versus dual azimuth solution. 

Before Image After Image
Single Azimuth
Dual Azimuth
A single vs dual azimuth stack with a particular focus on the deeper packages where both resolution and illumination are critical.

By combining innovative acquisition solutions with high-end imaging workflows, TGS can leverage existing GeoStreamer coverage and provide the step-change in quality that this underdeveloped region deserves.

Before Image After Image
Conventional denoise
Advanced denoise
Conventional image denoise compared to sparse plane-wave decomposition in an area where general weak reflectivity is adjacent to complex structures.

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