Page 34: of Marine Technology Magazine (March 2025)

FEATURE LEGACY DATA

Reprocessing of legacy wide-azimuth towed streamer data acquired in 2010 using TLFWI resulted in signif cant improvements in subsalt imaging. Top - 2010 legacy velocity model overlaid with RTM;

Bottom - 2024 8Hz TLFWI velocity and its RTM.

in their acoustic or elastic versions, have brought tremen- Seismic imaging is moving towards even more advanced dous value to the reprocessing of legacy seismic data,” says algorithms, such as high-frequency multi-parameter elastic

Rongxin Huang, VP, US Imaging, Subsurface Imaging, Viri- FWI, with the aim of deriving accurate seismic reservoir at- dien. “Although TLFWI and FWI imaging were initially de- tributes (compressional wave velocity (Vp), shear wave ve- veloped for the most advanced data, i.e. OBN data with good locity (Vs), and density) directly. Legacy data on its own is low frequencies, long offsets, and excellent spatial and azi- increasingly insuf? cient to meet these advanced demands, muthal sampling, applying these technologies to legacy seis- says Huang. mic data, which are sometimes more than 25 years old and “New acquisitions providing better data, such as OBN, are often have poor low frequencies, short offsets, and limited expected to become mainstream in operators’ exploration and spatial sampling, still generates step-change improvements development programs in the next 5–10 years. This will be in the seismic images. facilitated by decreasing acquisition costs as new acquisition “The application of TLFWI and FWI Imaging has greatly un- technologies and more streamlined operations continue to im- locked the value of legacy data, allowing operators to reduce prove acquisition ef? ciency.” costs and shorten turnaround times (compared to acquiring This means that, while there is still considerable value in new seismic surveys) when better seismic images are needed legacy data, in challenging geological areas it needs to be to make important decisions for their prospects and reservoirs.” complemented by new acquisition for seismic imaging.

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