Hydrogen tightness evaluation in bedded salt rock cavern: A case study of Jintan,China

Hydrogen is regarded as one of the most important energy sources for the future. Safe, large-scale storage of hydrogen contributes to the commercial development of the hydrogen industry. Use of bedded salt caverns for natural gas storage in China provides a new option for underground hydrogen storage (UHS). In this study, the physical properties of multicomponent gases in UHS and salt rock are reviewed and discussed, along with the flow of hydrogen in the surrounding salt rock. Mathematical models of the two-phase multicomponent flow of the gas–brine system in the UHS were established. A numerical model of a simplified elliptical salt cavern was built to simulate the migration of the gas–brine system in the UHS. The hydrogen tightness of the UHS was evaluated through simulation with different storage strategies, salt rock and interlayer permeabilities, and gas components. The results indicate that: (1) Cyclic injection and withdrawal facilitate hydrogen leakage, which is accelerated by increasing the frequency. (2) The huff-n-puff of hydrogen gas in the injection and withdrawal cycles forces the gas into pore space and enhances the relative permeability of the gas phase. The migration of hydrogen and brine weakens the hydrogen tightness. Brine saturation is an important index for evaluating the hydrogen tightness of UHS. (3) The leakage rate of UHS increases with an increase in the permeability of the salt rock and interlayer and the total thickness of the interlayers. The average permeability K_wa weighted by the thickness of layers for the bedded salt formation is proposed to integrate three variables to facilitate field application of the simulation results. The critical K_wa is less than 3.02 × 10⁻¹⁷ m² if the recommended annual hydrogen leakage rate is less than 1%. (4) The difference between hydrogen and other gas species is another important factor in the leakage rate and should be considered. This study provides theoretical guidance for evaluating the feasibility of UHS in salt caverns and site selection in China.     

Effect of retrograde condensation on the production performance of organic hydrogen compounds energy

The gas-condensate reservoirs are typical organic fossil reservoirs of hydrogen compounds energy. With the development of gas-condensate reservoirs, a part of condensate liquid of hydrogen compounds will appear under the influence of retrograde condensation mechanism. However, the effects of retrograde condensation on the production performance of organic hydrogen compound energy with different well types are still not clear. In this study, a series of numerical simulation models were established to investigate the law of retrograde condensation with different well types and reservoir permeabilities. Furthermore, the effects of retrograde condensation on gas well productivity were analyzed by the comparison between the compositional modeling and black oil modeling results. Results show that the condensate oil for the fractured wells is mainly distributed around the fracture tips instead of the perforation intervals for the unfractured wells. The maximum oil saturation and condensate area of two fractures at ends are much larger than those of middle fractures. The retrograde condensation exhibits a negligible impact on the production of multiple fractured horizontal wells with a cumulative gas production reduction 0.87%–1.57%. Hydraulic fracturing, multiple fractures and high reservoir permeability are conducive to lower the impact of retrograde condensation on the production of organic hydrogen compounds energy.     

A detailed comparative performance study of underground storage of natural gas and hydrogen in the Netherlands

With the expected increase in the use of hydrogen as an energy carrier, large-scale underground storage sites will be needed. Unlike underground natural gas storage (UGS), many aspects on the performance of underground hydrogen storage (UHS) are not well understood, as there is currently no UHS in use for energy supply. Here we present the results of a detailed comparative performance study of UGS and UHS, based on an inflow/outflow nodal analysis. Three UGS sites in depleted gas fields and one in a salt cavern cluster in the Netherlands are used as case studies. The results show that although hydrogen can be withdrawn/injected at higher rates than natural gas, this can be limited by technical constraints. It also indicates that wider ranges of working pressures are required to increase the storage capacity and flow performance of an UHS site to compensate for the lower energy density of hydrogen.     

Underground hydrogen storage in a naturally fractured gas reservoir: The role of fracture

As hydrogen provides a high heating value with the least environmental impact, it can be considered as an energy carrier pioneer in following the global zero-carbon policies. Then, since storing hydrogen in large quantities can also be a valuable technique for alleviating energy shortages due to energy consumption fluctuations, underground hydrogen storage (UHS) is being explored further in today's world. To the best of our knowledge, the role of fracture on underground hydrogen storage performance has not comprehensively been evaluated. For the first time, in this study, the effects of fracture on hydrogen storage and production were investigated in a naturally fractured gas reservoir in the Middle East using a numerical simulation. Then, to determine whether the fracture was able to accelerate hydrogen production, UHS was evaluated under various conditions, including the fracture system, condensate presence, Initial hydrogen injection stage, cushion gas type, hydrogen storage commence time and different injection/production cycle duration. The results of this study proves that although a huge amount of hydrogen is invaded into the matrix during hydrogen injection, the fracture accelerates hydrogen production, resulting in higher hydrogen recovery and purity, which indicates fractures are suitable media for hydrogen storage. However, it should be noted that the purity of hydrogen produced from naturally fractured reservoirs (NFR) decreases more rapidly than a conventional one during a single cycle due to the higher mixing of gases in the fracture. In the case of the initial stage of hydrogen injection, fractures are not found to be attractive as storage media. Therefore, it is necessary to analyze the fracture effects as a storage media under various situations and stages. In addition, alternative gas injection revealed that nitrogen injection into cushion gas resulted in the highest hydrogen production in the entire porous media, whereas methane injection led to the highest hydrogen recovery in the fracture media. Also, the rapid injection/production cycle duration improved hydrogen recovery, indicating that the required time for high hydrogen invasion into the matrix is not provided during hydrogen injection.     

齐成伟带纵公式在带状高含硫气藏中的推广

齐成伟带纵公式不适用于带状高含硫气藏,根据气相渗流与液相渗流的相似原理和Roberts气体相对渗透率与含硫饱和度的关系,将齐成伟带纵公式的适用条件推广为高含硫气藏,推导出了带状高含硫气藏中纵向双分支水平井的拟三维产能预测公式,即齐成伟带纵公式的高含硫气藏推广公式。根据齐成伟带纵公式的高含硫气藏推广公式,分析了硫沉积量、渗透率各向异性系数、带状气藏长度、生产段井筒位置和生产段长度对产能的影响。分析结果表明:产能随着含硫饱和度或渗透率各向异性系数的增大而减小;相同井境下,含硫饱和度对产能的影响要明显大于渗透率各向异性系数;产能随着带状气藏长度的增大而减小;产能随着生产段井筒位置的增大先增大,后减小,且当生产段井筒处于气藏中央高度时,产能最大;产能随着生产段长度的增大而增大。     

Comprehensive study of the underground hydrogen storage potential in the depleted offshore Tapti-gas field

Hydrogen is becoming an alternative for conventional energy sources due to absence of any Greenhouse Gases (GHG) emissions during its usage. Geological storage of hydrogen will be potential solution for dealing with large volume requirement to manage uninterrupted Hydrogen supply-chain. Geological Storages such as depleted reservoirs, aquifers and salt caverns offer great potential option for underground hydrogen storage (UHS). There are several depleted gas fields in India. One of such field is located in Tapti-Daman formation. A comprehensive study is conducted to assess the possibility of hydrogen storage in this Indian field which is first of its kind. The geological characteristic of this site is assessed for its viability for storage. Additionally, several aspects including storage capacity, sealability, chemical and micro-biological stability, reservoir simulation, and production viability are assessed using various analytical and numerical models.The qualitative analysis of the Tapti-gas field suggests that the integrity of the storage site will be intact due to existing anticlinal four-way closed structure. The chemical and micro-biological losses are minimal and will not lead to major loss of hydrogen over time. The reservoir modeling results show that optimum gas production-injection scheme needs to be engineered to maintain the required reservoir pressure level in the Tapti-gas field. Also, the deliverability of the various seasonal storage time show that 80 days production scheme will be suitable for efficient operation in this field. Finally, a synergistic scheme to enable green energy production, storage, and transportation is proposed via implementation of UHS in the offshore Tapti-gas field.     

Review on using the depleted gas reservoirs for the underground H2 storage: A case study in Niigata prefecture,Japan

Underground hydrogen storage (UHS) in depleted hydrocarbon reservoirs is a prospective choice to store enormous volumes of hydrogen (H₂). However, these subsurface formations must be able not only to store H₂ in an effective and secure manner, but also to produce the required volumes of H₂ upon demand. This paper first reviews the critical parameters to be considered for geological analysis and reservoir engineering evaluation of UHS. The formation depth, the interactions of rock-brine-H₂, the caprock (seal) and well integrity are the most prominent parameters as far as UHS is concerned. In respect of these critical parameters, tentative H₂ storage is screened from the existing gas storage fields in the Niigata prefecture of Japan, and it was revealed that the Sekihara gas field is a suitable candidate for UHS with a storage capacity of 2.06 × 10⁸ m³ and a depth of 1000 m. Then, a series of numerical simulations utilizing CMG software was conducted to find out the extent to which critical parameters alter H₂ storage capacity. The results demonstrated that this field, with a recovery factor of 82.7% in the sixth cycle of production is a prospective site for H₂ storage.     

Underground hydrogen storage to balance seasonal variations in energy demand: Impact of well configuration on storage performance in deep saline aquifers

Grid-scale underground hydrogen storage (UHS) is essential for the decarbonization of energy supply systems on the path towards a zero-emissions future. This study presents the feasibility of UHS in an actual saline aquifer with a typical dome-shaped anticline structure to balance the potential seasonal mismatches between energy supply and demand in the UK domestic heating sector. As a main requirement for UHS in saline aquifers, we investigate the role of well configuration design in enhancing storage performance in the selected site via numerical simulation. The results demonstrate that the efficiency of cyclic hydrogen recovery can reach around 70% in the short term without the need for upfront cushion gas injection. Storage capacity and deliverability increase in successive storage cycles for all scenarios, with the co-production of water from the aquifer having a minimal impact on the efficiency of hydrogen recovery. Storage capacity and deliverability also increase when additional wells are added to the storage site; however, the distance between wells can strongly influence this effect. For optimum well spacing in a multi-well storage scenario within a dome-shaped anticline structure, it is essential to attain an efficient balance between well pressure interference effects at short well distances and the gas uprising phenomenon at large distances. Overall, the findings obtained and the approach described can provide effective technical guidelines pertaining to the design and optimization of hydrogen storage operations in deep saline aquifers.     

Research on two‐phase flow considering hydrogen crossover in the membrane for a polymer electrolyte membrane fuel cell

Hydrogen crossover has an important effect on the performance and durability of the polymer electrolyte membrane fuel cell (PEMFC). Severe hydrogen crossover can accelerate the degradation of membrane and thus increase the possibility of explosion. In this study, a two‐phase, two‐dimensional, and multiphysics field coupling model considering hydrogen crossover in the membrane for PEMFC is developed. The model describes the distributions of reactant gases, current density, water content in membrane, and liquid water saturation in cathode electrodes of PEMFC with intrinsic hydrogen permeability, which is usually neglected in most PEMFC models. The conversion processes of water between gas phase, liquid phase, and dissolved water in PEMFC are simulated. The effects of changes in hydrogen permeability on PEMFC output performance and distributions of reactant gases and water saturation are analyzed. Results showed that hydrogen permeability has a marked effect on PEMFC operating under low current density conditions, especially on the open circuit voltage (OCV) with the increase of hydrogen permeability. On the contrary, the effect of hydrogen permeability on PEMFC at high current density is negligible within the variation range of hydrogen permeability in this study. The nonlinear relations of OCV with hydrogen diffusion rate are regressed.     

Use of slim holes with liquid feedzones for geothermal reservoir assessment

Production and injection data from slim holes and large-diameter wells at four geothermal fields (Oguni, Japan; Sumikawa, Japan; Takigami, Japan; Steamboat Hills, U.S.A.) were analyzed in order to establish relationships (1) between injectivity and productivity indices, (2) between productivity/injectivity index and borehole diameter, and (3) between discharge capacity of slim holes and large-diameter wells. The productivity and injectivity indices for boreholes with liquid feedzones are more or less equal. Except for the Oguni boreholes, the productivity and injectivity indices display no correlation with borehole diameter. Thus, the productivity index (or, more importantly, the injectivity index in the absence of discharge data) from a slim hole with a liquid feed can be used to provide a first estimate of the probable discharge capacity of a large-diameter geothermal production well. The large-diameter wells at the Oguni, Sumikawa and Steamboat Hills geothermal fields have a more or less uniform inside diameter, and the discharge capacity of these wells (with liquid feedzones) can be predicted using Pritchett's “scaled maximum discharge rate” in conjunction with discharge data from slim holes. Because of the non-uniform internal diameter for large-diameter Takigami wells, it is not possible to use a simple scaling rule to relate the discharge capacities of slim holes and large-diameter wells at Takigami; therefore, a numerical simulator was used to model the available discharge data from Takigami boreholes. The results of numerical modeling indicate that the flow rate of large-diameter Takigami production wells with liquid feedzones can also be predicted using discharge and injection data from slim holes.     

Productivity analysis of fractured wells in reservoir of hydrogen and carbon based on dual-porosity medium model

Hydrogen is usually locked in energy-rich organic compounds and there is almost no pure hydrogen in nature. Organic compounds produced in reservoirs of hydrogen and carbon are an important source of hydrogen production. Understanding the productivity characteristics reservoirs of hydrogen and carbon is the important step to ensure adequate hydrogen energy. This study analyzes the production of hydraulically fractured organic reservoir of hydrogen and carbon. First, based on the diffusion mechanism in reservoir matrix, a multi-scale dual-porosity medium model of reservoir of hydrogen and carbon is established. Then, the mathematical model is solved and verified through a historical matching of field gas production data. Finally, parameter analysis was performed to determine the key parameters to improve the recovery efficiency in organic reservoir of hydrogen and carbon. Results show that improving fracture permeability can improve gas recovery efficiency of hydrocarbon reservoirs. The matrix desorption can develop natural gas production for a long period. Long sizes of hydraulic fractures have large contact surfaces for gas diffusion and increase gas generation and cumulative gas production. The proposed model can predict and analyze the production performance of reservoirs of hydrogen and carbon.     

Evaluating the hydrogen storage potential of shut down oil and gas fields along the Norwegian continental shelf

The underground hydrogen storage (UHS) capacities of shut down oil and gas (O&G) fields along the Norwegian continental shelf (NCS) are evaluated based on the publicly available geological and hydrocarbon production data. Thermodynamic equilibrium and geochemical models are used to describe contamination of hydrogen, loss of hydrogen and changes in the mineralogy. The contamination spectrum of black oil fields and retrograde gas fields are remarkably similar. Geochemical models suggest limited reactive mineral phases and meter-scale hydrogen diffusion into the caprock. However, geochemical reactions between residual oil, reservoir brine, host rock and hydrogen are not yet studied in detail. For 23 shut down O&G fields, a theoretical maximum UHS capacity of ca. 642 TWh is estimated. We conclude with Frigg, Nordost Frigg, and Odin as the best-suited shut down fields for UHS, having a maximum UHS capacity of ca. 414 TWh. The estimates require verification by site-specific dynamic reservoir models.     

First assessment of an area potentially suitable for underground hydrogen storage in Italy

Hydrogen storage can help achieve climate change and reduce greenhouse gas emissions. This paper presents a first assessment of the suitability of northeastern Italy for underground hydrogen storage (UHS). The study focuses on the analysis of publicly available well data, which allowed identifying geological formations potentially suitable for UHS. The most promising area, known as the “Treviso Area” consists of both saline aquifers and depleted gas fields. One of the key petrophysical properties, i.e. porosity, was calculated for each of the five wells revealing conditions potentially suitable for UHS by applying empirical formulas to geophysical log data. For the two depleted gas fields, a hydrogen injection simulation was also performed. This work is a pioneer study and lays the foundation for hopeful further analyses, which could help implement the recently launched “North Adriatic Hydrogen Valley” initiative.     

Hydrogen-induced calcite dissolution in Amaltheenton Formation claystones: Implications for underground hydrogen storage caprock integrity

With the rising potential of underground hydrogen storage (UHS) in depleted oil and gas reservoirs or deep saline aquifers, questions remain regarding changes to geological units due to interaction with injected hydrogen. Of particular importance is the integrity of potential caprocks/seals with respect to UHS. The results of this study show significant dissolution of calcite fossil fragments in claystone caprock proxies that were treated with a combination of hydrogen and 10 wt% NaCl brine. This is the first time it has been experimentally observed in claystones. The purpose of this short communication is to document the initial results that indicate the potential alteration of caprocks with injected hydrogen, and to further highlight the need for hydrogen-specific studies of caprocks in areas proposed for UHS.     

Development of a Sievert apparatus for characterization of high pressure hydrogen sorption materials

A volumetric gas absorption (Sievert) apparatus has been developed to measure hydrogen absorption and desorption at pressures up to 700 bar and temperatures between 240 K and 320 K. The apparatus is designed to reduce uncertainty for high pressure measurements while maintaining proper temperature control in the sample. Pressure-composition isotherms (PCI) and kinetics measurements of a well-studied material, LaNi₅ have been obtained for validation of the apparatus. Measurements of both absorption and desorption PCI curves as well as full absorption kinetics data have been obtained for TiCrMn to examine the performance at high pressures, as well as to examine the thermodynamic hysteresis effect in TiCrMn for applications in metal hydride system design. Due to this hysteresis, the thermodynamics of the absorption reaction differ significantly from those of the desorption reaction, which must be accounted for when considering thermal design of a metal hydride reactor and the suitability of the metal hydride for energy storage applications.     

Blasingame decline theory for hydrogen storage capacity estimation in shale gas reservoirs

The estimation of storage capacity is crucial for underground hydrogen storage. Shale gas reservoirs have low permeability and porosity, so it is the potential site for hydrogen storage. The study is based on the depleted shale gas reservoirs with multiple flow mechanisms (diffusion, desorption and seepage). Firstly, this paper, using Laplace transformation, point source function and Stehfest inversion, presents a semi-analytical solution for bottom-hole pressure response with hydrogen duration injection. Then we, considering the multiple flow mechanisms, deduce a material balance equation specifically for shale gas reservoirs and plot modified type curves based on the Blasingame decline analysis theory. Furthermore, we discuss the effects of different critical parameters related to hydrogen storage capacity on type curves. In the final part, we describe in detail the method of obtaining hydrogen reserves using type curves. The proposed one can estimate the hydrogen volume in fractures and matrix systems, and get the actual underground storage volume through pressure response, compared with the hydrogen storage capacity calculated by the volumetric method. This study is helpful for the hydrogen capacity estimation of shale gas underground storage on-site.     

Initial and residual trapping of hydrogen and nitrogen in Fontainebleau sandstone using nuclear magnetic resonance core flooding

Hydrogen is among a few promising energy carriers of the future mainly due to its zero-emission combustion nature. It also plays an important role in the transition from fossil fuel to renewable. Hydrogen technology is relatively immature and serious knowledge gaps do exist in its production, transport, storage, and utilization. Although the economical generation of hydrogen to the scale required for such transition is still the biggest technical and environmental challenge, unlocking the large-scale but safe storage is similarly important. It is difficult to store hydrogen in solid and liquid states and storing it in the gaseous phase requires a huge volume which is just available in subsurface porous media. Sandstone is the most abundant and favourable medium for such storage as carbonate rock might not be suitable due to potential geochemical reactions.It is well established in the literature that interaction of the host rock-fluid and injected gas plays a crucial role in fluid flow, residual trapping, withdrawal, and more generally storing capacity. Such data for the hydrogen system is extremely rare and are generally limited to contact angle measurements, while being not representative of the reality of rock-brine-hydrogen interaction(s). Therefore, we have conducted, for the first time, a series of core flooding experiments using Nuclear Magnetic Resonance (NMR) to monitor hydrogen (H₂) and Nitrogen (N₂) gas saturations during the drainage and imbibition stages under pressure and temperature that represent shallow reservoirs. To avoid any geochemical reaction during the test, we selected a clean sandstone core plug of 99.8% quartz (Fontainebleau with a gas porosity of 9.7% and a permeability of 190 mD).Results show significantly low initial and residual H₂ saturations in comparison with N₂, regardless of whether the injection flow rate or capillary number were the same or not. For instance, when the same injection flow rate was used, H₂ saturation during primary drainage was 4% and it was <2% after imbibition. On other hand, N₂ saturation during the primary drainage was 26% and it was 17% after imbibition. However, when the same capillary number of H₂ was utilised for the N₂ experiment, the N₂ saturation values were ～15% for initial gas saturation and 8% for residual gas saturation. Our results promisingly support the idea of hydrogen underground storage; however, we should emphasise that more sandstone rocks of different clay mineralogy should be investigated before reaching a conclusive outcome.     

氮气泡沫剂性能评价及在大庆油田的应用

研制了适用于大庆油田的WT-1、WT-2、WT-3三套氮气泡沫剂体系。首先进行了静态评价实验,考察了温度、矿化度、含油饱和度等因素对三种氮气泡沫剂体系发泡体积、泡沫半衰期等性能的影响。实验结果表明:三种氮气泡沫剂体系适用于油藏温度小于55℃、矿化度小于5000mg/L、含油饱和度低于20%的油藏。然后,选用泡沫剂体系WT-1进行了动态评价实验,考察了发泡剂浓度、岩心渗透率、注入速度等因素对泡沫剂性能的影响。动态实验结果表明:气液比(氮气∶泡沫剂)介于1∶1～2∶1之间为最佳,注入速度对产生泡沫的质量没有明显影响,气液混注比气液交替注入效果好。大庆油田北2-丁2-59井组应用研制的氮气泡沫剂体系调剖后,启动压力平均升高0.7MPa,吸水剖面得到了有效调整,9口采油井中有6口井受效,整个井组累计增油3486t。     

Geochemical reactions-induced hydrogen loss during underground hydrogen storage in sandstone reservoirs

Underground hydrogen storage (UHS) appears to be an important means as a large-scale and long-term energy storage solution. A primary concern of UHS is the in-situ geochemical reactions-induced hydrogen loss. In this context, we performed geochemical modelling to examine the hydrogen loss associated with hydrogen dissolution and fluid-rock interactions using PHREEQC (Version 3) as a function of temperature and pressure. We also performed geochemical modelling with kinetics to investigate the potential hydrogen loss in two commercial gas storage reservoirs (Tubridgi and Mondarra) in Western Australia against the reservoir mineralogy, fluid properties, depth and temperature.Our results show that increasing pressure and temperature only slightly increases hydrogen solubility in brines without minerals. Increasing salinity slightly decreases the solubility of hydrogen in brines. The saturated hydrogen aqueous solution almost does not react with silicate and clay minerals, which is favorable for underground hydrogen storage in quartz-rich sandstone reservoirs. However, unlike silicate and clay minerals, carbonates like calcite triggers up to 9.5% hydrogen loss due to calcite dissolution induced hydrogen dissociation process. Kinetic simulations show that Tubridgi only leads to 0.72% of hydrogen loss, and Mondarra causes 2.76% of hydrogen loss as a result of reservoir calcite dissolution and hydrogen dissociation in brines in 30-year time. Nearly over 87% of calcite cement from Mondarra may be dissolved in 30-year, suggesting potential risks associated with wellbore stability. In conclusion, geochemical reactions-induced hydrogen loss would be minor for UHS in porous media, and we argue that deep calcite-free reservoirs together with calcite-free caprocks would be preferable for underground hydrogen storage.     

CFD simulation of heat transfer and phase change characteristics of the cryogenic liquid hydrogen tank under microgravity conditions

The heat transfer and phase change processes of cryogenic liquid hydrogen (LH₂) in the tank have an important influence on the working performance of the liquid hydrogen-liquid oxygen storage and supply system of rockets and spacecrafts. In this study, we use the RANS method coupled with Lee model and VOF (volume of fraction) method to solve Navier-stokes equations. The Lee model is adopted to describe the phase change process of liquid hydrogen, and the VOF method is utilized to calculate free surface by solving the advection equation of volume fraction. The model is used to simulate the heat transfer and phase change processes of the cryogenic liquid hydrogen in the storage tank with the different gravitational accelerations, initial temperature, and liquid fill ratios of liquid hydrogen. Numerical results indicate greater gravitational acceleration enhances buoyancy and convection, enhancing convective heat transfer and evaporation processes in the tank. When the acceleration of gravity increases from 10^?2 g0 to 10^?5 g0, gaseous hydrogen mass increases from 0.0157 kg to 0.0244 kg at 200s. With the increase of initial liquid hydrogen temperature, the heat required to raise the liquid hydrogen to saturation temperature decreases and causes more liquid hydrogen to evaporate and cools the gas hydrogen temperature. More cryogenic liquid hydrogen (i.e., larger the fill ratio) makes the average fluid temperature in the tank lower. A 12.5% reduction in the fill ratio resulted in a decrease in fluid temperature from 20.35 K to 20.15 K (a reduction of about 0.1%, at 200s).