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For subsurface commercial ventures or environmental projects that rely on maps of faulted horizons, accurate maps are fundamental. Fault topology provides an ideal tool for analysis of connectivity of fault systems. The data required to undertake the analysis is straightforward to extract from fault maps and can readily be compared to analogue data. In this paper we introduce the concept of fault topology and present existing and new analogue data. To get the most from applying topology the analysis must be coupled with knowledge of the structural history. This includes, the magnitude of faulting, the number of phases of activity and the angle of intersection of successive faulting events. We present a series of case studies that firstly illustrate how topology can capture and define variations in connectivity of fault systems and, secondly, demonstrate how fault topology can be used to identify potential anomalies.

We introduce a method for separating residual statics and NMO velocities by maximising sparsity in tau-v and tau-p domains. Surface Consistent statics are computed without a-priori knowledge about velocities needed for NMO corrections. In such way static time shifts will not be applied to compensate velocity errors. The new approach provides accurate focusing and positioning of the reflectors without needs to iterate updates of residual statics and velocities.

Ideal datasets for stratigraphic interpretation have high resolution, high level of continuity, high S/N, and high amplitude fidelity. In the deep water Gulf of Mexico (DW GOM), detailed geologic interpretation, like faults and channels, for subsalt Wilcox reservoirs is challenging due to complex salt overburden, poor illumination, and low resolution. However, it is becoming more feasible in recent years with advances in geophysics, i.e., new seismic data acquisition (e.g., WAZ, staggered WAZ with long offsets, and OBN) (Ourabah et al., 2015; Michell et al., 2017), velocity modeling technology (e.g., diving wave FWI, reflection FWI) (Peng et al., 2018), and more advanced imaging technology (e.g., LSRTM) (Schuster, 1993; Wang et al., 2016). In this paper, we present the customized workflow and results from a comprehensive reimaging project, with the purpose of preparing seismic data to reveal subsalt Wilcox stratigraphy.

Full Waveform Inversion (FWI) has become a standard method for generating high-resolution subsurface velocity models. Advances in FWI now allow the use of the full recorded wavefield, including diving waves, primary reflections, and multiples, leading to improved velocity updates even below the maximum penetration depth of diving waves. These detailed velocity models enhance seismic imaging and provide valuable input for Quantitative Interpretation (QI), which is essential for reservoir characterisation. We present here two case studies that illustrate the benefits of FWI for QI purposes. The first study, offshore Norway, applies elastic FWI to handle strong velocity contrasts beneath thick chalk layers, demonstrating how high-resolution velocity and seismic images improve fault detection and stratigraphic amplitude-versus-angle (AVA) inversion. The second case study, onshore Oman, showcases recent advances in land FWI and FWI Imaging, leading to sharper fault imaging and better stratigraphic AVA inversion when combining high-frequency velocity models with improved seismic images. These two case studies highlight the importance of retrieving velocity models within the same frequency bandwidth as the seismic images to accurately capture thin geological features. They also demonstrate the added value of using FWI-derived velocity models to enhance subsequent stratigraphic AVA inversion.

Cameroon’s Douala/Kribi-Campo (DKC) and Rio del Rey (RDR) basins offer significant exploration opportunities, underpinned by advanced seismic reimaging, integrated geological evaluation and modern interpretation techniques. In the RDR Basin, focus is shifting from the mature shallow Miocene-Pliocene plays to deeper Cenozoic turbidites and the Cretaceous succession, where improved imaging and regional analogues point to significant untapped resources. Meanwhile, reimaged 3D data in the DKC Basin illuminates stratigraphic, structural, and combination trap opportunities and improves understanding of complex channel systems and salt-related plays. Together, these insights demonstrate how modern imaging and integrated geological analysis can unlock prospectivity across both basins. With the 2025 Licensing Round now open, Cameroon presents a fresh opportunity for discoveries and renewed exploration success.

Renewed exploration success in the Kazakhstan Sector of the Caspian Sea (KSCS) depends on a critical reassessment of existing results and a redefined understanding of the region’s hydrocarbon potential. This study presents one such reassessment, integrating geological and geophysical data with newly reprocessed seismic data from the northern KSCS.

For shallow injectite reservoir monitoring using narrow azimuth towed streamer data, 4D full-waveform inversion (FWI) improves production monitoring and correctly identifies two separate softening responses, which can be correlated with gas injection and gas exsolution. In addition, a previously unidentified softening response is also observed which, using well production data, may be interpreted as geo-mechanical extension in the overburden. Migration with individual velocities from 4D FWI resolves depthing issues beneath reservoirs by correctly accounting for velocity changes in the subsurface.

The emergence full-waveform inversion (FWI), such as Time-lag FWI (TLFWI), has enabled the production of high-resolution velocity models and FWI Images in offshore salt settings. However, consistent success with FWI for onshore data has been elusive, as land seismic data often has a low signal-to-noise ratio especially at the low frequencies, limited offsets and poor density. Recent land acquisition designs and improved processing technology help overcome some of these challenges, and better land FWI examples are emerging. Our recent survey, located in the northern Sultanate of Oman, suffers from a large 6 km2 exclusion zone due to an outcropping salt body. Conventional top-down tomography failed to build a reliable velocity model, thus preventing decent imaging and interpretation of the complex shallow geology. Alternatively, the use of FWI relies on the full wavefield and is less sensitive to the lack of near-offset data. Starting from a simplistic model with minimal prior information regarding the subsurface, TLFWI successfully built a high-resolution 30 Hz velocity model. The resulting 30 Hz TLFWI Image provided superior image compared to conventional techniques and helped define the complex geology within the non-shooting region by delineating the shape of the shallow salt diapir and revealing faults planes.

The Sureste Basin in southeastern Mexico contains complex geological features, including extensional and compressional structures, salt deformations, rafted Mesozoic sections, and over-pressured shale diapirs. A recent onshore seismic acquisition using dynamite sources yielded lower-frequency, longer offset, full-azimuth data than previous vintages. However, permitting challenges caused suboptimal acquisition conditions, with reduced charge sizes and significant data gaps. Despite these obstacles, the use of a Time-lag Full-waveform Inversion (TLFWI) workflow, followed by FWI Imaging, proved crucial in resolving salt geometries, slow shale velocities, and velocity variations across faults and basins, significantly improving the deeper Mesozoic target imaging. Additionally, this study presents the limitations of TLFWI-based iterative model building when high-quality data is unavailable and underscores the need to combine TLFWI with more recent and improved datasets to further reduce exploration risks.