Fifth EAGE Global Energy Transition Conference & Exhibition (GET 2024)

This work mainly aims to evaluate gas flow behavior in sandstone for different gas types and enhance the understanding of the role of capillary pressure and gas displacement efficiency during underground storage. With this motive, we conducted a series of gas core-flooding experiments into brine-saturated sandstone core samples using three different gases (CO2, CH4, and H2), at ambient temperature. We integrated an X-ray scanning technique to detect the gas residual after the core-flooding experiment. We mainly report that:

1- Gas core-flooding experiments showed that CO2 exhibited slightly the highest average gas saturation by ≈ 40%, while the average gas saturation for H2 and CH4 were almost similar ranging between 25–30%. However, the gas residuals in the sample were zero for all gases. These outcomes suggest that the gas residuals in this sandstone sample are unaffected by the gas type, indicating the high potential for gas recovery (especially for hydrogen during withdrawal cycles), and the high displacement efficiency in sandstone rocks.

2- The calculated capillary numbers at constant flowrate (2 cc/min) were in very low values (×10−8), suggesting that all gases entered the pores immediately during the injection, and acted as a non-wetting phase.

Evaluation of potential well injectivity and storage capacity is crucial for CO2 sequestration in saline aquifers. Well testing prior to CO2 injection is a standard tool to address these questions providing information about well-reservoir connection, reservoir properties and boundaries. Well test designs may include short-term brine production or water- or CO2-injection with following long-term well shut-in with pressure measurements. This paper focuses on designing and interpreting such well tests employing pressure transient analysis (PTA). PTA-interpretation of simulated well test responses for different reservoir configurations has shown that the standard analytical PTA models for single-phase (water) flow can be used to interpret well tests with all designs above, including CO2-injection. The brine-replica approach, introduced previously, has been successfully tested for interpreting simulated well test responses for CO2 injection. The approach enables interpretation of CO2 injection well tests via adjustments of wellbore storage and skin when CO2 plume is localized near the well, while the brine properties govern estimation of reservoir flow capacity and boundary conditions. These results have practical applications in designing and interpreting well tests before CO2 injection. The paper concludes with discussion of the well tests designs discussed above, highlighting their advantages and limitations in practice of well testing.

The identification and characterisation of potentially problematic shallow soil conditions is vital in building an integrated ground model and ultimately defines the site investigation of an offshore wind farm. In this case study, the Sub-Bottom Imager (SBI) was used to de-risk the area of interest. The SBI from Kraken Robotics is a 3D acoustic data acquisition system used most commonly to detect linear and discrete objects in the sub-surface; such as cables, buried boulders or unexploded ordnance. Increasingly, however, it is being used to interpret stratigraphic layers in shallow soils.

This study outlines the process to which the SBI was able to interpret and map stratigraphic layers and buried boulders across a site where Wind Turbine Generator (WTG) piles were known to be refusing. The exact depth and location of potentially problematic units such as high strength clays, dense sands and cobble/boulder units were able to be defined. Ultimately, the SBI interpretation was used to supplement the integrated ground model and aid in the decision as to where best to locate the WTG piles.

To achieve the Dutch policy objective to reduce carbon emissions by 55% in 2030, a shift from fossil towards renewable energy resources is required. Within the Netherlands, geothermal energy is a proven renewable energy resource, but currently only with a limited number of operating installations. Presently producing geothermal projects in the Netherlands are generally located in areas where abundant subsurface data is available.

However, subsurface data coverage is poor in roughly half of the country, including major residential and industrial areas with high heat demand. Improving the data coverage in these areas would increase the benefit-risk ratio of geothermal projects, which would greatly support the development of these projects.

To address these data shortcomings, EBN and TNO-AGE have been tasked by the Ministry of Economic Affairs and Climate to embark on a geothermal exploration campaign, which includes reprocessing of vintage data, the acquisition of new, long-offset 2D seismic to improve the subsurface imaging and to allow reliable interpretation to a depth of at least 6 km and the drilling of a number of research wells.

This paper describes the geophysical work program, which was executed between late 2018 to mid-2024, and outlines further plans of the SCAN project.

Multiple opportunities for deep geothermal energy exist across the UK ranging from historical industrial activity (coal mining and hydrocarbon drilling) to pristine development in sedimentary basin and granite intrusions. This paper focuses on the Worcester Graben which underlies major conurbations of the West Midlands from Brimingham (in the north) to Bristol (in the south), but the methodology outlined can be expanded across the UK. Geothermal development is at an early stage in the UK due to a surfeit of coal, gas and oil. The shift to alternative, renewable energy sources has commenced in the country from the viewpoint of both politics (pressure on emission reductions) and economic (decline in production of traditional energy sources, increase in price and security of supply). An extensive database in the form of reports, seismic and drilling data exists and can be accessed through multiple sources. Additional data (seismic and drilling) will be required to fully evaluate opportunities as the principal target of this historical data focused on hydrocarbons and therefore the location is not optimal. A window of opportunity exists for early investors to accelerate the development of geothermal energy in the UK over the next decade.

For decades, the world knew only two compressed air energy storage (CAES) facilities, serving as backup and power plant black-start solution or offering frequency regulation. Several CAES developments have been started since then, but hardly any evolved into full-scale developments.

Meanwhile, integration of renewables presents challenges to the electricity system: increased curtailment, system instability and GHG-emissions from fossil-fuelled power plants remaining online as back-up. Long duration energy storage, like the CAES-projects Corre Energy is co-developing across Europe, offers a solution to decarbonize the electricity system, while reducing curtailment, stabilizing the electricity system, reducing demand for back-up plants and substantially reducing GHG-emissions. CAES can store massive amounts of energy in solution-mined salt caverns. Due to the increasing disbalance between electricity demand and the growing, fluctuating production of renewables it is quickly gaining in popularity.

To offer the solutions the future electricity system requires, the technology has technically advanced over the past decade. Capacities have increased significantly, maximum pressure has tripled (requiring deeper caverns), and by increasing cavern volume the duration of compression and generation has drastically increased. Finally, instead of natural gas, the fuel the plant needs for heating up the expanding air will be hydrogen as soon as available.

High voltage sub-seabed cables are becoming more common within seas around the world in the form of electrical interconnectors, offshore wind farm export and inter array cables.

This study focuses on the survey of the Viking Link interconnector cable between the UK and Denmark in the southern North Sea. Whilst an interconnector cable may not be directly linked to an offshore wind farm (OWF), the results of this study can be applied to OWF export and inter array cables. The Sub Bottom Imager™ (SBI) 3D acoustic profiler was used in conjunction with a Teledyne TSS 350 cable tracking system.

A 10 km comparison line was acquired to compare the TSS 350 top of product (ToP) data and the SBI ToP interpretation. The results of the comparison showed that the ToP from both systems had good alignment in both absolute depth and general cable trend.

Unlike an electromagnetic system, a 3D acoustic volume not only provides the position of the cable but also information on how the cable is interacting with the shallow soils. This can provide valuable information on why a cable has a varying burial depth and how to approach challenging shallow soils when it comes to trenching design.

This work is a study on the impact of sedimentary heterogeneity on groundwater flow and heat transport with a focus on meander-belt fluvial successions acting as low-enthalpy geothermal reservoirs. Geocellular models were generated to represent three types of meander belts produced by rivers that were ca. 12 m deep and include km-scale long and wide point-bar elements. Well doublets of typical spacing were placed on individual point-bar elements. Groundwater-flow and heat transport models were developed using MODFLOW 2005 and MT3D-USGS, respectively. The results suggest a relationship between the shape of the thermal plume and aspects of sedimentary heterogeneity. Mud plugs are a significant cause of asymmetry on thermal plume propagation, whereas discontinuous mud drapes have limited impact. The presence of openwork gravels, which act as thief zones, does not necessarily cause a reduction in thermal breakthrough time, although their impact is dependent on their orientation relative to the well doublet. The results of this study can assist the optimization of well-doublet planning based on knowledge of the subsurface. Yet, the impact of sedimentary heterogeneity in the successions of meandering rivers warrants further investigation, to be undertaken considering a wider natural variability of meander-belt sizes, architecture and styles of facies heterogeneity.

In this study an integrated workflow to predict microseismic events during CO2 injection has been proposed. The workflow is based on Thermo-Hydro-Mechanical coupling simulations. The study demonstrates that the majority of events occur at the onset of injection and the number of events, their moment magnitudes and the energy released will reduce as injection proceeds and pressure changes become more transient. This integrated approach would allow for cost-effective MMV strategies.

As the number of carbon storage projects are increasing, there is a need to develop cost-effective and reliable subsurface monitoring systems. Conventional permanent reservoir monitoring (PRM) systems are probably too costly for such purposes, and hence a cheaper, less precise but at the same time reliable system is in need. Several researchers have suggested that fibre optic sensing techniques or DAS can be used, and we discuss possibilities and limitations. We find that the DAS-technique has developed rapidly over the last decade and that it is probably ready for field implementations on several future CO2-projects, especially those where CO2 is injected into a saline sandstone aquifer. Since DAS-data acquired at the seabed is measuring shear-waves, we suggest to use exploit shear wave resonance effects for overburden monitoring.