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Ocean bottom node (OBN) seismic
Reliable imaging from shallow to deep-water environments
Improve subsurface clarity and reduce uncertainty with cost-efficient OBN imaging
Our ocean-bottom seismic processing solutions unlock new insights beneath the sea floor. We use a comprehensive suite of advanced algorithms and workflows to maximize the value of multicomponent data. By leveraging full azimuthal and offset coverage, we enable the construction of accurate earth models and robust subsurface imaging using the complete recorded wavefield. Where appropriate we also incorporate additional data, including mode-converted shear waves recorded on horizontal components—from node, cable, or fiber systems— to further enhance reservoir characterization and subsurface interpretation. Our approach helps operators make informed decisions, whether for energy exploration, development, or monitoring.
Comparison between wide-azimuth towed streamer RTM with FWI velocity model overlay (top) and FWI-derived reflectivity/model from full azimuth ultra long offset OBN dataset offshore US (bottom): The transition from streamer-based RTM to full azimuth OBN enables enhanced salt geometry accuracy and deeper subsurface image.
Shallow water
Our approach harnesses decades of expertise and the latest technology to tackle the distinctive complexities presented by shallow water environments. Our specialized workflows are designed to effectively handle complex issues related to acquisition geometry, sampling, and signal fidelity. We also employ advanced noise attenuation and wavefield deconvolution methods to mitigate the challenges of surface waves, guided waves, shear noise levels and strong water layer multiples, thus ensuring high-quality reservoir imaging. Furthermore, multiples are leveraged to provide additional subsurface illumination through full-wavefield imaging, thereby helping to compensate for acquisition gaps and enhance imaging results.
The same seismic line in the Gulf of Suez imaged with narrow-azimuth towed streamer data (left) and full-azimuth OBN data (right). Yellow arrows highlight event dips as measured in wells, demonstrating how full-azimuth OBN delivers clearer subsurface characterization and improved geological accuracy.
Deep water
Our deep-water ocean-bottom seismic solutions support a wide range of applications, from focused reservoir monitoring to large-scale exploration surveys. Reliable results in these challenging environments depend on precise correction for acquisition-related effects, such as receiver positioning, node clock drift, and variations in water velocity. We also apply advanced noise and multiple attenuation techniques to improve data quality. SLB uses established workflows for elastic velocity model building that make full use of the entire recorded wavefield—including both PP and PS wave data. By combining robust technology with extensive operational expertise, we consistently extract maximum value from OBN datasets, providing effective solutions for even the most complex geological challenges.
Comparison of a seismic section in the Campos Basin, Brazil. The top image shows narrow-azimuth towed streamer (NAZ TS) seismic data, imaged using the Kirchhoff algorithm with an earth model derived from the same NAZ TS dataset. The bottom image presents depth-migrated OBN (Ocean Bottom Node) seismic data, utilizing a velocity model derived from the full-azimuth OBN dataset. This comparison highlights how full-azimuth OBN acquisition and imaging bring more clarity to presalt targets.
Joint PP-PS imaging
In complex subsurface settings, joint PP-PS imaging integrates compressional (PP) and converted shear wave (PS) data from OBN surveys. This approach enhances interpretation in regions where PP- wave data alone encounters ambiguities, as PS images are intrinsically sensitive to lithology variations and less sensitive to fluid content.
SLB applies established workflows to extract shear wave splitting and perform joint elastic inversion, combining PP and PS data within a unified earth model. By inverting both datasets together, we derive robust earth models that honor the complementary information each mode provides. This results in clearer imaging, improved prediction of petrophysical properties, and more confident structural delineation. These methodologies are proven in geologically challenging environments, across targets ranging from shallow to deep and water depths from tens of meters to over a kilometer.
Interleaved depth-migrated PP (compressional wave) and PS (converted shear wave) seismic images from an offshore Norway field demonstrate a strong correlation between both datasets. This comparison shows how certain geological events can be tracked with greater clarity on the PS images, providing enhanced subsurface interpretation and improved reservoir characterization compared to using PP data alone.
4D PP-PS
4D seismic data is a key tool for managing oil and gas fields, providing detailed insight into how reservoirs change over time in response to injection and supporting optimized production strategies and intervention planning. By incorporating both compressional (PP) and converted shear waves (PS) in these studies, we gain a clearer picture of subsurface changes—due to the reduced sensitivity of converted waves to fluid saturation—facilitates the separation of pressure effects from saturation changes. Our proven workflows and experience ensure fast data processing and turnaround, making reservoir management more efficient and supporting better production decisions.
4D amplitude maps from surveys six years apart in the Norwegian North Sea. Joint PP-PS interpretation enhances understanding of saturation versus pressure dynamic changes in the reservoir. Left: PP data highlights saturation and pressure changes due to water flow between injector and production wells. Right: PS data is dominated by pressure effects.
Long offset full waveform inversion (FWI)
OBN acquisition flexibility enables the recording of surveys with full azimuth coverage and very long offsets. In geologically complex settings, this extended diving wave illumination improves the performance of FWI, supporting faster convergence and reducing reliance on the initial subsurface model. Multiparameter elastic full waveform inversion is then used to further refine the subsurface model, helping to deliver high-quality imaging and interpretation products.
Enhanced subsalt imaging in the offshore US, based on long-offset Full Waveform Inversion (FWI), is illustrated by comparing RTM results and velocity models from wide-azimuth towed streamer (WAZ TS) and Ocean Bottom Node (OBN) data. The OBN dataset, with its full azimuth coverage and ultra-long offsets (highlighted by the blue box showing WAZ TS limits), provides superior subsalt illumination and more accurate velocity models than WAZ TS, reducing exploration risk in complex offshore environments.
