First Break - Volume 43, Issue 6, 2025

A comprehensive seismic reservoir characterisation study was conducted in a gas field in Argentina, utilising geostatistical AVA seismic inversion to generate input for reliable static and dynamic model simulation. The study encompassed a range of disciplines, including petrophysics, rock physics modelling and geostatistical AVA seismic inversion, followed by effective porosity co-simulation.

The key advantage of the geostatistical inversion method lies in its ability to integrate all available data, i.e. wells, seismic, and geological knowledge, resulting in outcomes that honour all input and produce reliable results.

A notable aspect of this study was the use of 3D prior probabilities models for geostatistical inversion which proved to be crucial for better characterisation of litho-facies across the area, outperforming the 1D approach.

The results of the geostatistical inversion, combined with the conceptual depositional model and previous seismic attributes study, showed significant consistency, increasing confidence in the outcomes of the geostatistical inversion. The results of this study will be used to build static models of the field, enabling estimation of the in-place gas volume and its associated uncertainty. These models will also serve as input for dynamic simulations for the future development of this field.

This article expands on the EAGE extended abstract ‘Structural Styles and Lithology Changes at the Mesozoic Base from Ultra-Large 3D Seismic’, to be presented at the 86^th EAGE Annual Conference in Toulouse. The project’s interpretation and the structural grid for the Norwegian Continental Shelf are publicly available, a shared resource for researchers, students, and energy companies.

The study covers the details of a seismic interpretation of the Mesozoic base — a major unconformity mapped at the top of the Permian Zechstein Supergroup and the acoustic basement, where Zechstein onlaps the older strata. This surface underlies key Triassic, Jurassic, and Cretaceous hydrocarbon units, important for subsurface mapping, exploration, and petroleum systems modelling. Using a reprocessed, ultra-large broadband 3D seismic dataset (78,450 km²) across the North (NNS), Central (CNS), and South (SNS) zones of the Norwegian North Sea and 817 wells, the study integrates recent advances in salt tectonics and the Zechstein lithology research (Figure 1). Previous findings are integrated into a consistent interpretation of structural styles and lithological variation. Understanding Mesozoic base morphology and Zechstein compositional trends has significant implications for identifying prospective plays and reservoirs, including the Zechstein salt bed potential for underground storage suitability.

Hydrogen (H2) is viewed worldwide as one of the key pathways to reducing GHG emissions, especially in hard to abate sectors. However, the beneficial implementation of hydrogen as a fuel for transport, and in industries such as steel production requires a constant, reliable supply of hydrogen independent of the availability of energy. Therefore, hydrogen storage will be needed on a range of time scales, and over a range of volumes. Geological storage in porous reservoirs offer the largest storage ‘containers’, with volumes large enough to cover even seasonal cycles. However, this also means that H2 storage will be cyclic, and this cyclical nature in combination with the variable timeframes of that storage introduce complexity into the system at multiple scales. Effective and efficient operation of H2 storage sites thus requires understanding of how both injection rate itself, and how cyclical injection/ withdrawal cycles will impact fluid (e.g., H2-formation water, H2-buffer gas) interactions in the reservoir. To further develop this understanding, we utilise analogue and numerical modelling in addition to petrographical analysis to identify potential areas of further research within this underexplored topic.