Search

Subsurface geological formations can be utilized to safely store large-scale (TWh) renewable energy in the form of green gases such as hydrogen. Successful implementation of this technology involves estimating feasible storage sites, including rigorous mechanical safety analyses. Geological formations are often highly heterogeneous and entail complex nonlinear inelastic rock deformation physics when utilized for cyclic energy storage. In this work, we present a novel scalable computational framework to analyse the impact of nonlinear deformation of porous reservoirs under cyclic loading. The proposed methodology includes three different time-dependent nonlinear constitutive models to appropriately describe the behavior of sandstone, shale rock and salt rock. These constitutive models are studied and benchmarked against both numerical and experimental results in the literature. An implicit time-integration scheme is developed to preserve the stability of the simulation. In order to ensure its scalability, the numerical strategy adopts a multiscale finite element formulation, in which coarse scale systems with locally-computed basis functions are constructed and solved. Further, the effect of heterogeneity on the results and estimation of deformation is analyzed. Lastly, the Bergermeer test case—an active Dutch natural gas storage field—is studied to investigate the influence of inelastic deformation on the uplift caused by cyclic injection and production of gas. The present study shows acceptable subsidence predictions in this field-scale test, once the properties of the finite element representative elementary volumes are tuned with the experimental data. [ABSTRACT FROM AUTHOR]

Geological porous reservoirs provide the volume capacity needed for large scale underground hydrogen storage (UHS). To effectively exploit these reservoirs for UHS, it is crucial to characterize the hydrogen transport properties inside porous rocks. In this work, for the first time in the community, we have performed H 2 /water multiphase flow experiments at core scale under medical X-ray CT scanner. This has allowed us to directly image the complex transport properties of H 2 when it is injected or retracted from the porous rock. The important effective functions of capillary pressure and relative permeability are also measured, for both drainage and imbibition. The capillary pressure measurements are combined with MICP data to derive a receding contact angle for the H 2 /water/sandstone rock system. The rock core sample is a heterogeneous Berea sandstone (17 cm long and 3.8 cm diameter). Our investigation reveals the interplay between gravitational, capillary, and viscous forces. More specifically, it illustrates complex displacement patterns in the rock, including gravity segregation, enhancement of spreading of H 2 due to capillary barriers, and the formation of fingers/channel during imbibition which lead to significant trapping of hydrogen. These findings shed new light on our fundamental understanding of the transport characteristics of H 2 /water relevant for UHS. [ABSTRACT FROM AUTHOR]

Underground hydrogen storage (UHS) in initially brine-saturated deep porous rocks is a promising large-scale energy storage technology, due to hydrogen's high specific energy capacity and the high volumetric capacity of aquifers. Appropriate selection of a feasible and safe storage site vitally depends on understanding hydrogen transport characteristics in the subsurface. Unfortunately there exist no robust experimental analyses in the literature to properly characterise this complex process. As such, in this work, we present a systematic pore-scale modelling study to quantify the crucial reservoir-scale functions of relative permeability and capillary pressure and their dependencies on fluid and reservoir rock conditions. To conduct a conclusive study, in the absence of sufficient experimental data, a rigorous sensitivity analysis has been performed to quantify the impacts of uncertain fluid and rock properties on these upscaled functions. The parameters are varied around a base-case, which is obtained through matching to the existing experimental study. Moreover, cyclic hysteretic multiphase flow is also studied, which is a relevant aspect for cyclic hydrogen-brine energy storage projects. The present study applies pore-scale analysis to predict the flow of hydrogen in storage formations, and to quantify the sensitivity to the micro-scale characteristics of contact angle (i.e., wettability) and porous rock structure. [ABSTRACT FROM AUTHOR]

Underground Hydrogen Storage (UHS) is an emerging large-scale energy storage technology. Researchers are investigating its feasibility and performance, including its injectivity, productivity, and storage capacity through numerical simulations. However, several ad-hoc relative permeability and capillary pressure functions have been used in the literature, with no direct link to the underlying physics of the hydrogen storage and production process. Recent relative permeability measurements for the hydrogen-brine system show very low hydrogen relative permeability and strong liquid phase hysteresis, very different to what has been observed for other fluid systems for the same rock type. This raises the concern as to what extend the existing studies in the literature are able to reliably quantify the feasibility of the potential storage projects. In this study, we investigate how experimentally measured hydrogen-brine relative permeability hysteresis affects the performance of UHS projects through numerical reservoir simulations. Relative permeability data measured during a hydrogen-water core-flooding experiment within ADMIRE project is used to design a relative permeability hysteresis model. Next, numerical simulation for a UHS project in a generic braided-fluvial water-gas reservoir is performed using this hysteresis model. A performance assessment is carried out for several UHS scenarios with different drainage relative permeability curves, hysteresis model coefficients, and injection/production rates. Our results show that both gas and liquid relative permeability hysteresis play an important role in UHS irrespective of injection/production rate. Ignoring gas hysteresis may cause up to 338% of uncertainty on cumulative hydrogen production, as it has negative effects on injectivity and productivity due to the resulting limited variation range of gas saturation and pressure during cyclic operations. In contrast, hysteresis in the liquid phase relative permeability resolves this issue to some extent by improving the displacement of the liquid phase. Finally, implementing relative permeability curves from other fluid systems during UHS performance assessment will cause uncertainty in terms of gas saturation and up to 141% underestimation on cumulative hydrogen production. These observations illustrate the importance of using relative permeability curves characteristic of hydrogen-brine system for assessing the UHS performances. • Experimentally measured hydrogen-brine relative permeability curves show distinct characteristics compared to that of other fluid systems. • UHS performances under different relative permeability curves are compared. • Relative permeability curves from other fluid systems are not suitable to act as proxy to hydrogen-brine system in reservoir-scale UHS simulation. [ABSTRACT FROM AUTHOR]

Underground hydrogen (H 2) storage in saline aquifers is a viable solution for large-scale H 2 storage. Due to its remarkably low viscosity and density, the flow of H 2 within saline aquifers exhibits strong instability, which needs to be thoroughly investigated to ensure safe operations at the storage site. For the first time, we develop a lattice Boltzmann model tailored for pore-scale simulations of the H 2 -brine system under typical subsurface storage conditions. The model captures the significant contrast of fluid properties between H 2 and brine, and it offers the flexibility to adjust the contact angle to suit varying wetting conditions. We show that the snap-off is enhanced in a system with a high capillary number and a small contact angle. These conditions lead to a low recovery factor, which is unfavorable for H 2 production from the aquifer. Moreover, the relative permeability curves, computed from the simulation results, exhibit distinct behaviors for H 2 and brine. In the case of the wetting phase, the relative permeability can be quantified using the quadratic expression, whereas for the non-wetting phase, the relative permeability exhibits a nearly linear behavior, and saturation alone appears insufficient to characterize the relative permeability at large saturations of non-wetting phase. This implies that different formula for liquid and gas phases may be employed for continuum-scale simulations. • A pore-scale lattice Boltzmann model is developed for H 2 -brine system. • A higher capillary number and a smaller contact angle promote the snap-off event. • Relative permeability curves for H 2 and brine exhibit distinct behaviors. [ABSTRACT FROM AUTHOR]

Underground Hydrogen Storage (UHS) is an attractive technology for large-scale (TWh) renewable energy storage. To ensure the safety and efficiency of the UHS, it is crucial to quantify the H 2 interactions with the reservoir fluids and rocks across scales, including the micro scale. This paper reports the experimental measurements of advancing and receding contact angles for different channel widths for a H 2 /water system at P = 10 bar and T = 20 °C using a microfluidic chip. To analyse the characteristics of the H 2 flow in straight pore throats, the network is designed such that it holds several straight channels. More specifically, the width of the microchannels range between 50 μ m and 130 μ m. For the drainage experiments, H 2 is injected into a fully water saturated system, while for the imbibition tests, water is injected into a fully H 2 -saturated system. For both scenarios, high-resolution images are captured starting the introduction of the new phase into the system, allowing for fully-dynamic transport analyses. For better insights, N 2 /water and CO 2 /water flows were also analysed and compared with H 2 /water. Results indicate strong water-wet conditions with H 2 /water advancing and receding contact angles of, respectively, 13°–39°, and 6°–23°. It was found that the contact angles decrease with increasing channel widths. The receding contact angle measured in the 50 μ m channel agrees well with the results presented in the literature by conducting a core-flood test for a sandstone rock. Furthermore, the N 2 /water and CO 2 /water systems showed similar characteristics as the H 2 /water system. In addition to the important characterization of the dynamic wettability, the results are also crucially important for accurate construction of pore-scale simulators. [Display omitted] • Dynamic contact angles for H 2 /water/glass system were measured using a microchip. • H 2 dynamic contact angles decreased with increasing channel width. • H 2 advancing and receding contact angles were found, respectively, 13–39° and 6–23°. • Similar contact angles were found for H 2 , N 2 and gaseous CO 2. [ABSTRACT FROM AUTHOR]

Characterizing the wettability of hydrogen (H 2)–methane (CH 4) mixtures in subsurface reservoirs is the first step towards understanding containment and transport properties for underground hydrogen storage (UHS). In this study, we investigate the static contact angles of H 2 –CH 4 mixtures, in contact with brine and Bentheimer sandstone rock using a captive-bubble cell device at different pressures, temperatures and brine salinity values. It is found that, under the studied conditions, H 2 and CH 4 show comparable wettability behaviour with contact angles ranging between [25°–45°]; and consequently their mixtures behave similar to the pure gas systems, independent of composition, pressure, temperature and salinity. For the system at rest, the acting buoyancy and surface forces allow for theoretical sensitivity analysis for the captive-bubble cell approach to characterize the wettability. Moreover, it is theoretically validated that under similar Bond numbers and similar bubble sizes, the contact angles of H 2 and CH 4 bubbles and their mixtures are indeed comparable. Consequently, in large-scale subsurface storage systems where buoyancy and capillary are the main acting forces, H 2 , CH 4 and their mixtures will have similar wettability characteristics. [Display omitted] • Static contact angles for H 2 –CH 4 /brine/rock systems were directly measured. • All gas mixtures showed comparable behaviour and no P, T or salinity dependency was found. • A theoretical validation of the results is presented based on the Young Laplace Eq. • For similar N B O and bubble sizes, the contact angles for H 2 and CH 4 are comparable. [ABSTRACT FROM AUTHOR]

• For the first time, we experimentally quantify the intrinsic contact angle of H2/Brine/Sandstone Rock. • The studies are done by developing a Captive-Bubble setup at high-pressure and elevated temperatures. • The measurements are done for different T, P, salinity, and rock type representing in-situ conditions. • With the results presented in this paper one can quantify relative permeability (Kr) and capillary pressure (Pc) curves for accurate reservoir-scale modeling and simulation. Subsurface porous formations provide large capacities for underground hydrogen storage (UHS). Successful utilization of these porous reservoirs for UHS depends on accurate quantification of the hydrogen transport characteristics at continuum (macro) scale, specially in contact with other reservoir fluids. Relative-permeability and capillary-pressure curves are among the macro-scale transport characteristics which play crucial roles in quantification of the storage capacity and efficiency. For a given rock sample, these functions can be determined if pore-scale (micro-scale) surface properties, specially contact angles, are known. For hydrogen/brine/rock system, these properties are yet to a large extent unknown. In this study, we characterize the contact angles of hydrogen in contact with brine and Bentheimer and Berea sandstones at various pressure, temperature, and brine salinity using captive-bubble method. The experiments are conducted close to the in-situ conditions, which resulted in water-wet intrinsic contact angles, about 25 to 45 degrees. Moreover, no meaningful correlation was found with changing tested parameters. We monitor the bubbles over time and report the average contact angles with their minimum and maximum variations. Given rock pore structures, using the contact angles reported in this study, one can define relative-permeability and capillary-pressure functions for reservoir-scale simulations and storage optimization. [ABSTRACT FROM AUTHOR]