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Net-transgressive, shallow-marine sandstone reservoirs overlain by thick mudstone seals are prime candidates for storage of CO2, H2 and thermal energy. Although these reservoirs have high net-to-gross ratios, analogous outcrops demonstrate a wide range of sedimentological heterogeneities that are sampled only sparsely or at low resolution in subsurface data. We use a combination of outcrop data, sketch-based reservoir modelling and flow diagnostics to assess the impact of sedimentological heterogeneities on subsurface storage.

The Cliff House Sandstone outcrop example comprises wave-dominated shoreface sandstones arranged in aggradationally-to-retrogradationally stacked parasequences, which overlie and pass up depositional dip into mudstone-dominated coastal plain, lagoonal and tidal flat deposits that encase channelized tidal and tidally influenced fluvial sandbodies. Reservoir models of this outcrop example demonstrate that effective horizontal permeability, flow patterns and displacement, and stratigraphic trapping potential are controlled by: (1) the packaging of shoreface sandstones into laterally extensive parasequences bounded by offshore mudstones; (2) the spatial distribution, connectivity and permeability of channelized sandbodies; and (3) the localized connections between channelized sandbodies and shoreface sandstones. The last two parameters are likely to be poorly constrained in subsurface seismic and well data, and their potential effects require evaluation in reservoir modelling studies.

The Bunter Sandstone Formation (BSF) is a target reservoir for the storage of CO2 in the UK Southern North Sea (UKSNS). Previous industry studies highlighted diagenetic features that influence fluid flow in the BSF but failed to identify the controls and patterns of regional diagenesis that are now needed to inform more accurate prediction of porosity distribution and connectivity for CO2 storage. This study presents a regional diagenetic model from the petrographical analysis of 78 samples from 12 wells in the northern UKSNS. Diagenetic cements (carbonates, sulfates and halite) are common. Most are early and episodic, patchy at local and regional scales, with periods of replacement and dissolution. Consequential fine-scale heterogeneous compaction textures are unrelated to current or maximum burial depths. Calcrete and dolocrete layers, associated with the formation of displacive eodiagenetic carbonate nodules, form discontinuous millimetre- to metre-thick vertical flow barriers. Halite and anhydrite are developed preferentially in coarser-grained sandstones, resulting in the ‘reservoir quality inversion’ noted in previous studies. There is abundant evidence for local, late mobilization and dissolution of halite and anhydrite, observed to preferentially affect samples from depths above c.1400 m, restoring some zones to good porosity. Additional high-density sampling and petrography is recommended, however, to provide the predictability required for CO2 storage.

The utilization of extensive saline aquifers for CO2 storage will require careful consideration of the potential pressure responses. The displacement of formation waters results in far-reaching pressure footprints that extend beyond the storage sites. Where multiple storage projects share a connected saline aquifer, the available pressure budgets for neighbouring projects may be negatively impacted. Structures such as faults and salt walls can potentially divide an aquifer into smaller hydraulic units.

The extent of hydraulic units in the Bunter Sandstone Formation (BSF) within the UK Southern North Sea (UKSNS) was investigated by structural interpretation of seismic data. A new classification scheme was developed to characterize the major structural features affecting the BSF and their likely impact on boundary conditions. The resultant boundary condition map indicates where structures are expected to inhibit pressure communication through displacement/dislocation of the BSF aquifer. The results were validated by pressure data, which confirmed the existence of variable pressure regimes across the BSF.

Understanding these boundary conditions is essential to support the strategic deployment of CO2 storage in the UKSNS and to maximize storage capacity. The methodology can also be applied to other regions where extensive saline aquifers are considered for CO2 storage.

Hot sedimentary aquifers (HSAs) have huge potential for low-carbon energy supply but remain a relatively untapped resource. For example, HSAs could meet 100 years of the UK national heat demand. The main technical barriers to HSA deployment are subsurface risks and associated well completion requirements. Numerous studies and policies have attempted to tackle these hurdles, but the sluggish implementation of HSA projects underscores the need for a deeper understanding of what works and what does not. Embracing a ‘learning from failure’ ethos, we compiled a comprehensive database of key parameters through a systematic review of publicly available information from 256 HSA projects across eight countries where data were widely available: Australia, Croatia, Denmark, France, Germany, Poland, The Netherlands and the UK. This database encompasses project specifics, borehole details, geological and hydrogeological parameters, associated risks, and mitigation strategies. Analysis revealed that 26% of HSA projects failed, mainly due to geological and hydrogeological (39% of all reasons), financial (26%), and technical (25%) issues. Mitigation or remediation strategies were implemented by 24% of both failed and running projects, resulting in a general decrease in failure rate over time. Successful projects emphasize the importance of robust pre-drilling site characterization and ongoing monitoring of the geothermal installations. We recommend the adoption of international standards for geothermal play classification and data reporting to enhance appraisal of HSA prospects. By quantifying key parameters for project failure and success, we hope to de-risk and inform better budgeting of HSA endeavours, thereby bolstering the success and viability of future projects.

A qualitative approach is presented for the preliminary screening of areas for the storage of radioactive waste or for geothermal energy production based on knowledge of damage zones. Different types of fault damage zones are described in relation to the geometries and kinematics of individual faults or pairs of faults. A new type of damage zone, termed a ‘fold-related damage zone’, is also defined. Some fold-related damage zones may be indirectly related to faulting, such as folding above a thrust ramp, while others may be associated with processes such as salt movement. This knowledge is applied to a regional fault map to predict areas of relatively intense faulting and fracturing in central and southern Germany. Forty examples of potential tip, linking, interaction, bend or fold-related damage zones have been identified, and more detailed fault maps and digital elevation model data have been examined for evidence of damage. More detailed work is required, however, to ascertain the extent of damage in these zones and their influence on fluid flow. For example, some damage zones may show lower porosity and permeability than the surrounding rock mass. This approach can be applied to fault maps in other regions to identify additional potential damage zones.

Understanding ancient hydrothermal fluid flow is critical for predictive models of geoenergy resources, including critical raw materials, oil and gas, geothermal energy, natural hydrogen, and fluid disposal reservoirs. This study proposes a novel approach, integrating U–Pb dating and fluid-inclusion geothermometry, to distinguish hydrothermal heating from the palaeo-ambient burial temperature (PABT) in palaeogeothermometric records.

Our approach combines fluid-inclusion geothermometry with absolute age and burial history to quantify if the palaeotemperature exceeded the PABT. Applied to the shelf of the Anadarko and Arkoma basins, we analysed three calcite cement samples from Mississippian-aged carbonate host rocks with ages of 318.2 ± 18.1, 305.0 ± 10.5 and 308.6 ± 2.5 Ma. Our results demonstrate temperature anomalies 44–144°C above PABTs of 41, 27 and 27°C, revealing prolonged Carboniferous–Permian hydrothermal fluid flow.

Combined with regional data, we interpret the hydrothermal fluid flow as originating from recharge on the Ouachita and Ancestral Rocky mountains, leading to gravity-driven fluid flow into the hot foredeep of the Anadarko and Arkoma basins, and out through regional stratigraphic aquifers with structural damage.

This paper facilitates heating-decarbonization policy implementation with regards to district-scale ground source heat pumps (GSHPs), demonstrating how favourability tools and geospatial visualization can inform communities’ and policy-makers’ net-zero decision-making. A map-based decision tool visualizes the geospatial relationships between heat resource, heat demand and socio-demographic consideration factors. A framework of six core geological and heat demand considerations is presented with additional socio-demographic data integration by the end user encouraged. An underpinning algorithm combines data, creating a resource favourability index, weighting of which is user defined. Capacity to dynamically integrate, visualize and manipulate intrinsic and external data enables informed policy decisions and system design. End users may direct specific geospatial queries combining all data types, allowing a non-geological expert, policy-maker or community organization to form a holistic understanding of the limitations and benefits to GSHP deployment. Initial findings in Scotland indicate that superficial deposit distribution primarily drives the geothermal resource extent; however, the heat demand distribution is a major spatial limitation to utilization. A key policy implication is the nature of the localized resource, which requires local knowledge and planning to utilize. Responsibility for realizing national carbon targets through such energy planning measures increasingly lies with local governments, to which this tool contributes a method of geoscience-to-policy communication.

An integrated understanding of H2 generation, migration, trapping and preservation is required to facilitate H2 exploration. Hydrogen-rich gas discoveries in the São Francisco Basin in Brazil enable investigation of these processes in intracratonic settings. We used major gas, stable isotope and noble gas isotope geochemistry to develop an advanced geochemical framework that demonstrates, via multiple lines of evidence, migration of components into the basin from underlying cratonic basement. Mass balance shows that hydrogen and helium derive from outside of the fracture-controlled reservoirs from which they were sampled. Radiogenic noble gas data indicate at least two crustal sources for the accumulated gas, from different thermal environments; neon isotope data suggest that one of these is the Archean crystalline basement. The H2- and He-bearing gases are associated with the eastern part of the basin, above the Pirapora Aulocagen, where thick-skinned deformation associated with the Araçuaí Orogeny may provide fluid-migration pathways between the basement and the basin fill. The Precambrian crystalline basement has a high H2 generation potential, but it was previously unknown whether basement-derived H2 gases could survive migration and accumulation without being entirely consumed by chemical and microbial reactions. While several wells contain an abiotic contribution to the alkane gases, indicating hydrogen consumption, H2 concentrations of up to 39% imply that, as with noble gases, it is possible for H2 to survive migration and accumulation on a regional scale. This discovery of natural H2 gas reservoirs supports a source–migration–trapping model, critical to define effective natural hydrogen plays, enabling economic exploration of this low-carbon resource.

Hydrogen will be crucial for powering energy hubs like Pennsylvania in the future. Here, we provide the first geological hydrogen storage resource assessment for the Commonwealth. We validate existing methods for estimating the pore volume available for hydrogen storage in hydrocarbon gas pools using industry-reported data. We estimate that Pennsylvania gas pools can store 1979 TWh (c. 59 Mt) of hydrogen working gas, which is ample storage potential for a hydrogen economy in the state. We evaluate the physical and chemical attributes of these pools to compare their efficacy for hydrogen storage. Fifty-three large, dry-gas, high-pressure, high-temperature pools in sedimentary units with favourable mineralogy and water chemistry could be particularly effective hydrogen storage sites. This work will help hydrogen development to proceed in a state that requires large quantities of energy storage and fuel in the future.

This study investigates the CO2 storage potential and 4D seismic monitoring capabilities of 64 depleted gas fields across the UK Continental Shelf (UKCS) and the Norwegian Continental Shelf (NCS), providing critical insights for optimizing carbon storage strategies. By analysing 4D seismic signal strength, time-shift measurements and theoretical storage capacities, the research identifies significant regional and field-specific variations. Overall, UKCS fields exhibit stronger amplitude responses, which can be attributed to distinct CO2 phase behaviour during injection where injected CO2 transitions from gaseous to supercritical phase. Time-shift analysis (0.2–3.1 ms in the UKCS; 0.1–2.6 ms in the NCS) consistently exceeds the minimum detectability threshold for towed streamer surveys (0.5 ms) and proves more reliable than amplitude changes, which rarely reach the required 17% normalized root mean square threshold. The non-linear relationship between seismic response and geological characteristics points to the need for tailored monitoring approaches. These findings highlight the critical role of reservoir properties, stratigraphic age and site-specific monitoring plans in guiding the design and deployment of effective carbon storage strategies in the North Sea.

Understanding the relations between indicator minerals, faults and temperatures is crucial for effective geothermal exploration. This study employs a novel data-driven analysis to investigate these relations across three distinct geothermal fields in California and Nevada in the USA: Coso, Brady and Desert Peak. Utilizing fault maps, land surface temperatures (LSTs) and indicator mineral maps (alunite, chalcedony, hematite, kaolinite and opal), non-spatial analyses (Kolmogorov–Smirnov tests, ANOVA and linear regression) were combined with spatial analysis (co-location analysis) to uncover associated patterns.

At Coso and Brady, alunite and kaolinite are closely linked to faults and elevated LSTs, while chalcedony shows negative correlations. Hematite aligns positively with LSTs but negatively with faults, and opal correlates positively with faults but not with LSTs. These trends align with geothermal alteration models that involve sulfuric acid or alkali-chloride fluid discharges. Desert Peak's blind geothermal system contrasts with the negative relations between its indicator minerals, faults and LSTs.

This research provides insights into integrating diverse datasets to enhance exploration strategies and reduce uncertainty. Fault surveys are essential for identifying heat and fluid pathways, while LST surveys are critical for detecting blind systems. In addition, the study underscores the need for data-driven approaches to explore subtle geological characteristics in geothermal exploration.

Western Australia provides ideal conditions for establishing carbon capture, utilization and storage (CCUS) hubs due to the co-location of abundant, highly suitable geological storage resources in saline aquifers and depleted fields with clusters of industrial emissions sources. These industrial emitters include sources with high CO2 concentrations from gas processing, ammonia and fertilizer production that form a relatively low-cost opportunity for the initial stages of a CCUS hub. The Pilbara CCUS hub concept modelled in this study covers three stages to build economies of scale up to 40 Mtpa CO2: (1) 4.3 Mtpa CO2 from higher CO2 concentration emissions sources, including reservoir CO2 separated from natural gas processing and high-CO2 streams from ammonia/fertilizer production; (2) 18.6 Mtpa CO2 from lower CO2 concentration emissions sources that require post-combustion CO2 capture and new industries including low-emissions hydrogen; (3) 14.2 Mtpa CO2 from domestic and Asia–Pacific countries. The introduction of low-emissions hydrogen production in the second stage demonstrates how low-emissions hydrogen and its derivative can lay the foundation for future green hydrogen/ammonia production and low-carbon steel. Excess storage capacity provides a new business opportunity to import CO2 from other parts of Australia and from the broader Asia–Pacific region. However, the large costs for post-combustion capture and shipping infrastructure will require a much higher carbon price, tax incentives or government subsidies than currently available, before the incorporation of these emissions sources would become economically feasible.

The future of geoenergy, as recently outlined by Gluyas and Fowler in their 2024 Geoenergy article (https://doi.org/10.1144/geoenergy2023-058), is driven by a need to transition to low-carbon energy technologies. Such a transition is closely intertwined with society; that is, individual consumers, households, communities, companies, non-governmental organizations, policymakers and other agents will be affected by and respond to changes in energy systems. We believe that it is imperative for the field of geoenergy to also study human, social and cultural aspects of geoenergy; areas that are usually covered by the arts, humanities and social sciences (AHSS). Despite an abundance of literature on the integration of AHSS disciplines in the field of (geo)energy, it often remains difficult to achieve its full potential in supporting the decarbonization of energy systems to benefit society. We argue that successful AHSS–geoenergy integration starts at research centres such as the Research Ireland Centre for Applied Geosciences (iCRAG), which provides research collaboration on a meso level. To achieve successful AHSS–geoenergy integration, we developed a roadmap based on the development of a positive research culture. We illustrate this with successful examples of AHSS–geoenergy integrated projects.