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Hydraulic stimulation of Enhanced Geothermal Systems (EGS) aims at boosting permeability to facilitate fluid circulation, while keeping a low induced seismicity. However, some stimulations have led to poor permeability enhancement or too high induced earthquakes, which suggests that further understanding is needed on poromechanical processes during stimulation. Here, we model a highly-monitored test performed at the Bedretto Underground Laboratory to investigate the impact of fluid injection on permeability enhancement and induced microseismicity. We examine three models: (1) a homogeneous fracture whose transmissivity is manually calibrated to reproduce the observed pressure evolution at the injection borehole (this model fails to capture the spatial distribution of pressure and the corresponding poromechanical processes); (2) an elastic fracture approach, where transmissivity changes locally as a function of fracture aperture following the cubic law (this model overestimates pressure after the onset of fracture slip); and (3) a viscoplastic fracture approach with strain weakening and dilatancy that yields an additional permeability enhancement after shear reactivation. The viscoplastic model captures the spatio-temporal coupled response of the fractured rock to hydraulic stimulation before and after shearing both in terms of pressure and microseismicity. Subsequently to the onset of shear failure, microseismic events occur in every injection cycle as the reactivation front advances when plastic strain and, thus, permeability surpass the previously achieved maximum value. This viscoplastic model permits estimating the extent of the stimulated fracture, the permeability enhancement and its impact on the local state of stress and pore pressure at surrounding fractures, representing a useful tool for the design of effective hydraulic stimulation.

To harness the immense potential of geothermal energy for non-intermittent baseload power, low-permeability crystalline hot rocks need to be hydraulically stimulated to create Enhanced Geothermal Systems (EGS) that enable economically profitable fluid flow rates. However, hydraulic stimulation is usually associated with seismic activity that has led to project cancellation in a few occasions. To improve our understanding of the coupled hydro-mechanical (HM) processes behind stimulation during both injection and post-injection stages (after shut-in), we numerically analyze three different stimulation protocols: constant-rate, step-rate, and cyclic injection with and without bleed-off after shut-in (and between cycles for the cyclic protocol). Simulation results show that the injection protocol has a higher influence on the HM response of the fracture than the total volume of injected water, which challenge scaling laws that relate the injection volume with the expected maximum magnitude of the induced earthquakes. The trade-off between maximizing permeability enhancement, while minimizing induced seismicity is not straightforward. In particular, bleeding-off the well after injection restricts induced seismicity, but at the expenses of limiting permeability enhancement. When considering stimulation of a single fault, all protocols yield comparable slip rates and, thus, magnitude of the induced earthquake, with the constant-rate injection being the fastest to induce the largest earthquake. The small differences in the HM response to hydraulic stimulation do not permit identifying a protocol that performs better than the others.

Background: The administration of biological drugs in inflammatory bowel diseases (IBD) is increasingly moving from intravenous to subcutaneous formulations. Aims: To evaluate the efficacy and safety of vedolizumab subcutaneous administration after switching from intravenous administration in ulcerative colitis (UC) patients in corticosteroid-free clinical remission. Methods: An observational, multicentre, prospective study was conducted by the Italian Group for the study of IBD (IG-IBD). UC patients in clinical remission (pMAYO < 2) not receiving steroids for > 8 months before the switch, and with at least 6 months of follow-up were included. Switch from intravenous to subcutaneous vedolizumab was defined as successful in patients not experiencing a disease flare (pMAYO ≥ 2) or needing oral steroids or stopping subcutaneous vedolizumab during the 6 months of follow-up after the switch. Results: Overall, 168 patients were included. The switch was a success in 134 patients (79.8%). Vedolizumab retention rate was 88.7% at month six. C-reactive protein and faecal calprotectin values did not change after the switch (p = 0.07 and p = 0.28, respectively). Ten of the 19 patients who stopped subcutaneous formulation switched back to intravenous formulation recapturing clinical remission in 80%. Side effects were observed in 22 patients (13.1%). Conclusion: Effectiveness of switching from intravenous to subcutaneous vedolizumab formulation in UC patients in steroid-free clinical remission is confirmed in a real-world setting.

Personalised medicine and the identification of predictors of the efficacy of specific drugs represent the ultimate goal for the treatment of ulcerative colitis (UC) in order to break the current therapeutic ceiling. JAK inhibitors are a new class of advanced therapies, orally administered, showing a good profile of efficacy and safety in both randomised controlled trials (RCTs) and real-world studies. Unfortunately, to date, it is not possible to draw the ideal profile of a patient maximally benefiting from this class of drugs to guide clinicians' therapeutic choices. Baseline clinical activities and inflammatory biomarkers, as well as their early variation after treatment initiation, emerged as the main predictors of efficacy from post hoc analyses of RCTs with tofacitinib. Similar findings were also observed in the real-life studies including mainly patients with a history of pluri-refractoriness to biological therapies. At last, a few new biomarkers have been explored, even though they have not been validated in large cohorts. This paper provides a review of the current knowledge on clinical variables and biomarkers predicting response to JAK inhibitors in UC.

Purpose Campylobacter is a frequent cause of enteric infections with common antimicrobial resistance issues. The most recent reports of campylobacteriosis in Italy include data from 2013 to 2016. We aimed to provide national epidemiological and microbiological data on human Campylobacter infections in Italy during the period 2017–2021. Methods Data was collected from 19 Hospitals in 13 Italian Regions. Bacterial identification was performed by mass spectrometry. Antibiograms were determined with Etest or Kirby-Bauer (EUCAST criteria). Results In total, 5419 isolations of Campylobacter spp. were performed. The most common species were C. jejuni (n = 4535, 83.7%), followed by C. coli (n = 732, 13.5%) and C. fetus (n = 34, 0.6%). The mean age of patients was 34.61 years and 57.1% were males. Outpatients accounted for 54% of the cases detected. Campylobacter were isolated from faeces in 97.3% of cases and in 2.7% from blood. C. fetus was mostly isolated from blood (88.2% of cases). We tested for antimicrobial susceptibility 4627 isolates (85.4%). Resistance to ciprofloxacin and tetracyclines was 75.5% and 54.8%, respectively; resistance to erythromycin was 4.8%; clarithromycin 2% and azithromycin 2%. 50% of C. jejuni and C. coli were resistant to ≥ 2 antibiotics. Over the study period, resistance to ciprofloxacin and tetracyclines significantly decreased (p < 0.005), while resistance to macrolides remained stable. Conclusion Campylobacter resistance to fluoroquinolones and tetracyclines in Italy is decreasing but is still high, while macrolides retain good activity.

BackgroundThe transition from in-hospital intravenous administration to subcutaneous therapies to treat inflammatory bowel disease (IBD) can raise some concerns among patients due to the self-administration concerns, the management of potential side effects and the overall worries related to a change of treatment. This study aimed at evaluating patients' opinion about the switch from intravenous to subcutaneous formulations and their knowledge on new available therapeutic options.MethodsWe conducted a survey using a questionnaire prepared by a team of gastroenterologists and nurses working at the IBD unit. It consists of 31 items and has been divided into four sections: descriptive, commitment, knowledge and passage mode opinion. The questions were formulated in Italian and conceived according to daily consultations with patients in everyday practice, without any previous piloting or specific medical literature reference. The survey was administered to consecutive IBD patients in intravenous biological treatment; patients currently or previously treated with subcutaneous therapy were excluded.ResultsFour hundred questionnaires were distributed to participants. As many as 311 patients (77.7%) completed the survey, while the remaining were excluded from the analysis; 155 (49.8%) patients were favorable to switch from intravenous to subcutaneous therapy, while only 78 (25.1%) disagreed. In univariate and multi-variate analysis, the approval rate for home therapy was significantly associated with the distance from the IBD center and work/family/personal commitments. Surprisingly, only a quarter of the IBD patients knew that almost all available therapeutic agents have a subcutaneous administration route. Regarding patients' opinion on the efficacy of subcutaneous administration of biological agents compared to intravenous drugs, 194 (63%) had no definite idea, while 44 (14%) believed that the effectiveness could be reduced.ConclusionThe transition from in-hospital to su

This dataset includes the input files of the numerical models used in the manuscript for simulating the hydraulic stimulation in the conceptual models as well as the Bedretto model with the executable file of the numerical code (CODE_BRIGHT). Each folder is named after the corresponding model in the manuscript described in the sections 3.1.1 and 3.2.1. In each folder, there is a file with the name of the folder ended as “_gen.dat” which contains the input data of the model, including material properties, initial and boundary conditions and the time intervals. There is also a file ended as “_gri.dat” that includes the information on the mesh. The file “root.dat” includes the name of the model. The file ended as “_bcf.dat” contains injection rate input for Bedretto model. To run the simulation, copy and paste Code_Bright executable file, i.e., “Cb_2021.exe”, in a folder that contains the input files and execute it.

When time series are observed with noise, the popular Augmented Dickey–Fuller (ADF) unit root test and Johansen's cointegration test are oversized: the ADF tends to conclude for stationarity too often and Johansen's test finds too many cointegrating relations. This fact is well-known but no simple solution has been proposed in the literature. In this work, we show why this happens and prove theoretically and by Monte Carlo simulations how three different filtering approaches can significantly improve the performance of the two tests applied to noisy data without harming their properties when observations are free from noise. We show how conclusions can change when using filtered time series in two real applications: one concerning wholesale electricity prices in European countries, and the second warning against pairs trading strategies based on spurious cointegrating relations among stock prices.

This dataset includes the input files of the numerical models used in the manuscript for simulating the hydraulic stimulation at the Bedretto lab. Each folder is named after the corresponding model in the manuscript, i.e., EP (Elastic Prescribed), EE (Elastic Embedded), and VE (Viscoplastic Embedded). In each folder, there is a file with the name of the folder ended as “_gen.dat” which contains the input data of the model, including material properties, initial and boundary conditions and the time intervals. There is also a file ended as “_gri.dat” that includes the information on the mesh. The file “root.dat” includes the name of the model. The file ended as “_bcf.dat” contains injection rate input.

This dataset includes the input files of the numerical models used in the manuscript for simulating the hydraulic stimulation in Enhanced Geothermal System with a single fracture setup. Each folder is named after the corresponding injection protocol in the manuscript, i.e., Constant, Step, and Cyclic. In each of these folders, there are two subfolders namely- Without Bleedoff and With Bleedoff. In the subfolders, the file ending with “_gen.dat” contains the input data of the model, including material properties, initial and boundary conditions and the time intervals. There is also a file ending with “_gri.dat” that includes the information on the mesh. The file “root.dat” includes the name of the model.

This guest editorial summarizes the topics and the papers selected for the Special Issue on Flexible and Resilient Urban Energy Systems. After rigorous reviewing process, 21 papers are accepted for publication. These 21 accepted papers cover various aspects of urban energy systems and are distributed as following: situational awareness of urban energy systems (2 papers), quantification metrics of flexibility and resilience of urban energy systems (3 papers), vulnerability modeling of urban energy systems under various extreme events (3 papers), planning of flexible and resilient urban energy systems (4 papers), robust and resilient operation and control of urban energy systems (4 papers), recovery and restoration strategy of urban energy systems (2 papers), and coordination and interoperability of interconnected energy systems (3 papers). The Guest Editorial Board hopes this Special Issue can provide a valuable information for future research and advancements in the field of flexible and resilient urban energy systems., QC 20230920

Hydroshearing, or shear stimulation, is recognized as the main method to exploit geothermal energy in hot low-permeability crystalline rocks at depth. It consists of enhancing permeability via injection-induced shear slip and dilation of preexisting fractures. , . Hydroshearing usually causes some induced microseismicity, sometimes of sufficient magnitude to be felt on the surface. Thus, high pressure fluid injection to enhance fracture permeability should be made carefully to avoid inducing earthquakes above the acceptable magnitude.

Geoenergies such as underground gas storage and energy storage, geothermal energy and geologic carbon storage are key technologies on the way to the foreseeable energy transition. The reservoir characterization in these projects remains challenging since predictive modeling approaches face limitations in identifying the spatial distribution of distinct lithologies and their hydro-mechanical properties from downwell testing procedures. Pumping tests are usually carried out to infer permeability, but offer only few observation points in space and require large extrapolation through inversion. The application of Physics Informed Neural Networks (PINN) offers a promising solution which can seamlessly incorporate field data, while enforcing the accordance with physical laws in the domain of study. This concept is implemented via two distinct loss terms for both the physical constraints and for the observational data in the loss function of an Artificial Neural Network (ANN). The physics-informed loss term contains a mass balance equation consisting of a storage and a diffusion component. The process is considered to be purely hydraulic and Darcy flow is assumed. The observational loss term compares the output of the ANN to a set of training data. This set consists of the system’s initial fluid pressure, as well as of a fluid pressure time series at the domain boundaries and at the borehole location. Preliminary results suggest that our PINN model is able to forecast the spatiotemporal fluid pressure distribution in a 2D domain for a variety of pumping test schemes. In this way, we give a first impression of the opportunities that PINN applications offer in the field of reservoir modeling.

To extend geothermal-energy power generation from hydrothermal systems to places without anomalies in the geothermal gradient, fractures of low-permeability rock- typically at 4-6 km depth to find <150°C - should be stimulated to create enhanced geothermal systems (EGS). However, most of the attempts to establish full-scale EGSs have resulted in high induced seismicity as a result of hydraulic stimulation, leading to project cancellation in some occasions. This has created a lot of insecurity in further investments in this kind of system. To achieve widespread deployment of EGSs alongside existing hydrothermal power plants, we need a thorough understanding of the effect of different hydraulic stimulation strategies on both permeability enhancement and induced seismicity. In this chapter, we compared three stimulation strategies in detail - constant rate, step rate and cyclic injection, for a range of dilatancy angles of the stimulated fracture. We find that the extent of fracture reactivation and pressure buildup depends on the injection scheme as well as the dilatancy angle. For a given dilatancy angle, we find that the cyclic-injection scheme provides the highest permeability enhancement as well as the highest slip, whereas both of them are observed to be the lowest for the step-rate injection.

Fluid injection into geological formations for energy resource development frequently induces (micro)seismicity. Moderate- to large-magnitude induced earthquakes may cause injuries and/or economic loss, with the consequence of jeopardizing the operation and future development of these geo-energy projects. To achieve an improved understanding of the mechanisms of induced seismicity, develop forecasting tools and manage the associated risks, it is necessary to carefully examine seismic data from reported cases of induced seismicity and the parameters controlling them. However, these data are challenging to gather together and are time-consuming to collate as they come from different disciplines and sources. Here, we present a publicly available, multi-physical database of injection-induced seismicity (Kivi et al., 2022a; 10.20350/digitalCSIC/14813), sourced from an extensive review of published documents. Currently, it contains 158 datasets of induced seismicity caused by various subsurface energy-related applications worldwide. Each dataset covers a wide range of variables, delineating general site information, host rock properties, in situ geologic and tectonic conditions, fault characteristics, conducted field operations, and recorded seismic activities. We publish the database in flat-file formats (i.e., .xls and .csv tables) to facilitate its dissemination and utilization by geoscientists while keeping it directly readable by computer codes for convenient data manipulation. The multi-disciplinary content of this database adds unique value to databases focusing only on seismicity data. In particular, the collected data aim at facilitating the understanding of the spatiotemporal occurrence of induced earthquakes, the diagnosis of potential triggering mechanisms, and the development of scaling relations of maximum possible earthquake magnitudes and operational parameters. The database will boost research in seismic hazard forecasting and mitigation, paving the way f

The global trend toward renewable power generation has drawn great attention to hydrogen Fuel Cells (FCs), which have a wide variety of applications, from utility power stations to laptops. The Multi-stack Fuel Cell System (MFCS), which is an assembly of FC stacks, can be a remedy for obstacles in high-power applications. However, the output voltage of FC stacks varies dramatically under variable load conditions; hence, in order for MFCS to be efficiently operated and guarantee an appropriate load-current sharing among the FC stacks, advanced converter controllers for power conditioning need to be designed. An accurate circuit model is essential for controller design, which accounts for the fact that the parameters of some converter components may change due to aging and repetitive stress in long-term operations. Existing control frameworks and parametric and non-parametric system identification techniques do not consider the aforementioned challenges. Thus, this paper investigates the potential of a data-driven method that, without system identification, directly implements control on paralleled converters using raw data. Based on pre-collected input/output trajectories, a non-parametric representation of the overall circuit is produced for implementing predictive control. While approaching equal current sharing within the MFCS, the proposed method considers the minimization of load-following error and mitigation of circulating current between the converters. Simulation results verify the effectiveness of the proposed method.

On November 26, 2021, the B.1.1.529 COVID-19 variant was classified as the Omicron variant of concern (VOC). Reports of higher transmissibility and potential immune evasion triggered flight bans and heightened health control measures across the world to stem its distribution. Wastewater-based surveillance has demonstrated to be a useful complement for clinical community-based tracking of SARS-CoV-2 variants. Using design principles of our previous assays that detect SARS-CoV-2 variants (Alpha and Delta), we developed an allele-specific RT-qPCR assay which simultaneously targets the stretch of mutations from Q493R to Q498R for quantitative detection of the Omicron variant in wastewater. We report their validation against 10-month longitudinal samples from the influent of a wastewater treatment plant in Italy. SARS-CoV-2 RNA concentrations and variant frequencies in wastewater determined using these variant assays agree with clinical cases, revealing rapid displacement of the Delta variant by the Omicron variant within three weeks. These variant trends, when mapped against vaccination rates, support clinical studies that found the rapid emergence of SARS-CoV-2 Omicron variant being associated with an infection advantage over Delta in vaccinated persons. These data reinforce the versatility, utility and accuracy of these open-sourced methods using allele-specific RT-qPCR for tracking the dynamics of variant displacement in communities through wastewater for informed public health responses.

As hydrothermal systems are limited to certain types of geologies, we need to create more Enhanced Geothermal Systems (EGSs) in order to scale electricity generation from geothermal energy. These are usually low-permeability rocks at depths of 4-6 km with temperatures >150ºC, which need to be stimulated to enable sufficient flow rates. Most of the previous attempts to create EGSs ended with high induced seismicity as an effect of hydraulic stimulation. The seismic activity led to cancellation of some projects along with creating a negative perception on both public and investors. Hence, it is crucial for us to have a detailed understanding of the hydro-mechanical (HM) processes taking place in the fractures leading to permeability enhancement (and consequent induced seismicity). We compare the HM response of the fracture for constant-rate injection, step-rate injection and cyclic injection protocols used in hydraulic stimulation. Our results suggest that the extent of fracture reactivation and pressure buildup relies on the injection protocol along with the dilatancy angle. For a particular dilatancy angle, we find that the cyclic injection protocol provides the highest permeability enhancement along with the highest slip, whereas both of them are observed to be the lowest for the step-rate injection protocol.

Geothermal energy presents a promising prospect as a substantial contributor to the globallow-carbon energy landscape. Most ofthe currently utilized energy comes from conventional geothermal systems that are either water or vapor dominated, and are limited to certain types of geologies. To scale up energy production from geothermal sources, exploration of alternative systems, such as Enhanced Geothermal Systems (EGS), supercritical geothermal systems, and closed loop geothermal systems, is imperative. Each of these systems, however, poses unique challenges for a successful deployment. In the case of EGS, hydraulic stimulation plays a critica! role in enhancing permeability within the poorly permeable, heatrich crystalline basement. A successful stimulation operation demands the achievement ofthe desired permeability, while effectively managing induced seismicity. A few EGS projects, notably Basel and Pohang, encountered difficulties in controlling postinjection seismicity, resulting in their eventual cancellation anda negative public perception of EGS. The injection protocols followed at these sites, namely step rate and cyclic injection protocols, were clearly inefficient in mitigating post-injection seismic events. Hence, it is essential to discern the differences between various injection protocols (i.e., constant rate, step rate and cyclic) in stimulation processes. We conducta numerical modeling study to investigate the hydromechanical (HM) response of a single fracture within an EGS to these protocols. The analysis revealed that these protocols yield comparable permeability enhancements. However, the cyclic injection protocol induced maximum slip during the injection phase, while the step rate protocol induced the largest slip during the post-injection phase. lmportantly, our findings emphasize that seismic activity primarily depends on the employed injection protocol rather than the vol u me of injected water. Simulation results also show that bleeding-off at

Geothermal systems require reliable reservoir characterization to increase the production of this renewable source of heat and electricity. We apply state-of-the-art Physics Informed Neural Networks (PINN) to model the fluid pressure evolution p(x,y,t) for the 2D reservoir domain. We set up a PINN for inferring p(x,y,t) by constraining an Artificial Neural Network’s (ANN) loss function with data and physics. In addition to time series measurements at the well location, we enforce the initial condition and boundary conditions. Since we lack observation points within deep geothermal reservoirs, we minimize the residual of a mass balance partial differential equation (PDE) on random collocation points inside the domain. Inside the PDE two data-driven ANNs are used to estimate the heterogeneous permeability field of the fractured reservoir k(x,y) and the flow rate at the injection borehole Q(t). We then train a separate ANN to estimate p(x,y,t), which leads to more stable modeling results than training these ANNs in parallel. We fine-tune these models by adapting the concept of dimensionless PDEs to the specific scaling requirements of ANNs. In addition, the weighting of loss terms is tested for several adaptive weighting schemes to find the optimum results. Our preliminary results indicate that with PINN and our current setup, we can infer the fluid pressure evolution for a high permeability contrast inside the reservoir while having only a small amount of observation points inside the domain.

Background & Aims: Subcutaneous vedolizumab formulation has been shown to be as effective and safe as the intravenous one in randomized control trials. Real-life data are limited especially for patients receiving long-term intravenous therapy. This study aimed to evaluate the safety and effectiveness of switching from intravenous to subcutaneous vedolizumab in a large cohort of patients with stable clinical remission.Methods: In this prospective cohort study, we enrolled consecutive patients attending our center between September 2021 and April 2022. The baseline demographic characteristics, 12- and 24-weeks follow-up clinical activity, C-reactive protein levels, and adverse events were recorded. The primary endpoint was to assess combined steroid-free clinical remission plus biochemical remission 24-week after the switch.Results: 93 patients (43 Crohn's disease, 50 ulcerative colitis), switched to subcutaneous vedolizumab after a median duration of intravenous treatment of 36 months [IQR 16-52]. At baseline, 80 patients (86%) had a combined remission. At 24-week, 89.2% (n=74) maintained combined steroid-free clinical remission plus biochemical remission. 25 adverse events were reported, mostly SARS-CoV-2 infections and injection site reactions, with a further four recurrence episodes. Twelve patients (12.9%) discontinued subcutaneous administration and restarted intravenous vedolizumab.Conclusions: Switching from intravenous to subcutaneous vedolizumab can be considered effective and safe for maintaining remission in patients with inflammatory bowel disease. In addition, this might reduce healthcare costs. However, large-scale real-life studies with long-term follow-up are necessary.

In this paper, we study a class of markets, among which we can mention agricultural and energy markets, characterized by seasonality, i.e., in which demand and/or supply conditions cyclically alternate with a precise and known periodicity. We propose a new theoretical framework based on a cobweb model with adaptive expectations, accordingly modified to be consistent with market’s seasonality. The model, consisting in a second-order non-autonomous difference equation, is investigated with the aim of understanding how the periodical nature of the market together with the agents’ expectation formation mechanism affects the resulting dynamics. We analytically prove the emergence of dynamical scenarios that are missing in the classic cobweb model for non-seasonal markets, such as quasi-periodic dynamics and an ambiguous role on stability of the expectation weight. Finally, we discuss their economic rationale with the help of numerical simulations. In such a peculiar economic framework, agents’ learning plays a key role to explain the dynamical properties of economic observables.

Fractures are pervasive in the subsurface, rendering both opportunities and challenges for geo-engineering applications since they provide permeable pathways for energy and mass transport. In particular, fractures dominate fluid flow, solute transport, and mechanical deformation, albeit they occupy a very small volume of a subsurface formation. The behavior of complex fracture networks stems from the aggregation of multiple individual fractures mutually interacting; for this reason, addressing the hydromechanical behavior of a single fracture should be investigated first to address more complicated field-scale fracture networks. To simulate macroscale processes in fractured porous media, there are two main approaches where fractures are represented either explicitly or implicitly via an equivalent continuum. In contrast to the explicit representation of fractures, which is conceptually simpler, the implicit framework has lower computational costs and implementation complexity. However, upscaling the inherent properties to represent equivalent fracture behaviors remains an open question. In this study, we investigate an approach based on the dual-continuum implicit representation of fractures surrounded by low-permeability rock matrix to accurately simulate hydromechanical processes. The approach treats fractures as equivalent continua with a manageable scale (>>1 ¿m) which facilitates numerical discretization, even for large-scale models containing multiple fractures. The simulation results indicate that a relatively thicker equivalent continuum layer (in the order of cm) can represent a fracture (with an aperture in the order of ¿m) and accurately reproduce the hydromechanical response to fluid injection into a fracture.

Geoenergies such as underground gas storage and energy storage, geothermal energy and geologic carbon storage are key technologies on the way to the foreseeable energy transition. The reservoir characterization in these projects remains challenging since predictive modeling approaches face limitations in identifying the spatial distribution of distinct lithologies and their hydro-mechanical properties from downwell testing procedures. Pumping tests are usually carried out to infer permeability, but offer only few observation points in space and require large extrapolation through inversion. The application of Physics Informed Neural Networks (PINN) offers a promising solution which can seamlessly incorporate field data, while enforcing the accordance with physical laws in the domain of study. This concept is implemented via two distinct loss terms for both the physical constraints and for the observational data in the loss function of an Artificial Neural Network (ANN). The physics-informed loss term contains a mass balance equation consisting of a storage and a diffusion component. The process is considered to be purely hydraulic and Darcy flow is assumed. The observational loss term compares the output of the ANN to a set of training data. This set consists of the system’s initial fluid pressure, as well as of a fluid pressure time series at the domain boundaries and at the borehole location. Preliminary results suggest that our PINN model is able to forecast the spatiotemporal fluid pressure distribution in a 2D domain for a variety of pumping test schemes. In this way, we give a first impression of the opportunities that PINN applications offer in the field of reservoir modeling.

Reliable reservoir characterization of the strata, fractures, and hydraulic properties is needed to determine the energy storage capacity of geothermal systems. We apply the state-of-the-art Physics-Informed Neural Networks (PINN) to model subsurface flow in a geothermal reservoir. A PINN can incorporate any physical laws that can be described by partial differential equations. We obtain a ground truth dataset by running a virtual pumping-well test in the numerical code “Code_Bright”. This model consists of a low-permeability rock matrix, intersected by high- permeability fractures. We approximate the reservoir permeability with an Artificial Neural Network (ANN) denoted by . Secondly, we model the fluid pressure evolution with the PINN by informing it about the experimental well-testing data. Since observation wells are sparse in space (only the injection well in our case), we feed into a hydraulic mass balance equation. The residual of this equation enforces the loss function of for random collocation points inside the domain. Our results indicate that the ANN is able to approximate even for a high permeability contrast. In addition, the successful interpolation of proves the PINN is a promising method for matching field data with physical laws. In contrast to numerical models PINNs shift the computational efforts toward the training, while reducing the resources needed for the forward evaluation. Nevertheless, training a 3D reservoir model can hardly be achieved on an ordinary workstation since the training data may include several millions of entries. In addition, computational costs increase due to the inclusion of multiphysics processes in the PINN. We plan to prepare the PINN model for training using parallelized GPUs to significantly increase the training speed of the ANNs.

Patients affected by inflammatory bowel disease (IBD) frequently report impaired quality of sexual life and complain of sexual dysfunctions. Both disease-specific features and psychological factors can be held responsible for these conditions. However, sexuality and all matters relating to sexual health are often wrongfully considered unrelated to IBD and, therefore, overlooked during medical visits. To overcome these difficulties and to best assess patients' perceptions about their sexual health status, the use of patient-reported outcomes (PROs) could represent a valid strategy. In real-world studies, several non-IBD specific questionnaires, exploring different domains of sexuality, have been applied and validated for the IBD population. This review summarizes the available evidence on sexual health among IBD patients and the data supporting the application of PROs to screen the quality of sexual life, as well as the rate and types of sexual dysfunctions, among IBD patients.

As our comprehension of the pathogenic mechanisms of inflammatory bowel disease (IBD) increases, the therapeutic armamentarium for its treatment can expand, and novel target therapies join the treatment pipeline. Interleukin (IL)-12 and IL23 are two key cytokines responsible for promoting and perpetuating bowel inflammation in IBD. Ustekinumab is a monoclonal antibody directed against the shared p40 subunit of both cytokines, and it was recently approved for the treatment of ulcerative colitis (UC). In the pivotal phase III UNIFI trial, ustekinumab showed a superiority over placebo in both clinical and endoscopic outcomes; furthermore, it was characterized by a favorable safety profile, with a similar rate of adverse events as compared with placebo. Recent evidence from real-life experiences have started accumulating, generally confirming the effectiveness and safety figures emerged from the registration studies. However, most of these observational studies enrolled multirefractory patients; moreover, comparative data with other target therapies are lacking, leaving physicians without clear indications about the appropriate positioning of ustekinumab in the therapeutic pipeline for UC. This review examines the basis of targeting IL12-23 in UC therapy and summarizes the data from both clinical trials and real-life studies, to highlight the main evidence already available and the research gaps that need to be filled for the optimal usage of ustekinumab in UC.

In this study, we present results of an in situ stress state estimation for the Los Humeros geothermal field (Mexico) located in the eastern section of the Trans-Mexican Volcanic Belt. During more than 40 years of geothermal energy production, issues related to induced seismicity, reservoir depletion, subsidence, and wellbore stability have occurred in Los Humeros. The in situ stress tensor, being one of the major controls on the above-mentioned phenomena, remains highly uncertain. The high temperatures of the geothermal reservoir at Los Humeros, often exceeding the critical point of water, promote difficulties in performing in situ stress measurements. In this study, based on data commonly acquired from drilling operations from eleven high-temperature wells within the Los Humeros caldera, we constrain the in situ stress state of the geothermal field. For this purpose, we employ borehole observations including borehole breakouts, instances of fluid circulation loss, and injection tests. Results from this study indicate predominantly strike-slip regime with a strong reverse component and NE-SW acting maximum horizontal stress. Utilizing slip and dilation tendency analysis, permeability and seismic activity of major fault zones within the geothermal field could be aptly explained by the acting stress regime. The outcome of this study provides valuable insights into the in situ stress state of the Los Humeros caldera and supports the exploration of conventional and unconventional (i.e., supercritical) geothermal resources.

This paper presents a novel scheme termed Optimization-based Ramping Reserve Allocation (ORRA) for addressing an ongoing challenge in Automatic Generation Control (AGC) enhancement, i.e., the optimal coordination of multiple Battery Energy Storage Systems (BESSs). While exploiting further the synergy between BESSs and slow ramping resources, the proposed scheme offers an insight into the energy-neutral operation, which is achieved by smoothly discontinuing the BESS participation along with the minimization of Area Injection Error (AIE), a variant of traditional Area Control Error (ACE). The first stage of ORRA is to incorporate Neural Networks (NNs) with the AIE in order to ensure a zero-mean of ramping reserves to be allocated among BESSs. These AIE signals are then used to formulate the optimal coordination of BESS as an online optimization problem, which is therefore feedback-driven. Finally, a distributed optimization algorithm is developed to solve the formulated problem in real-time, achieving a sublinear dynamic regret that quantifies the cost difference to the trajectory computed by a centralized optimizer with perfect global information. Consistent with the geographical distribution of BESSs, the proposed ORRA is fully distributed such that the algorithm can be executed in parallel at all nodes. Simulations on a modified IEEE 14-bus system are performed to illustrate the effectiveness and important features of ORRA.

We present a comprehensive, publicly accessible database of injection-induced seismicity. The database is sourced from a comprehensive review of more than 500 published documents and contains information for 158 cases of induced earthquakes from around the world. The collected earthquakes are associated with a variety of geoenergy applications, which can be broadly categorized into geologic gas storage, geothermal energy development, shale gas fracturing, research projects and wastewater disposal. The compilation comprises more than 70 variables, including general project information, host rock properties, ‎in situ site characteristics, fault attributes, operational parameters, and recorded seismicity data (both overall seismic activities and the largest event sequence). The developed database opens up opportunities for improved understanding of the causative mechanisms of injection-induced seismicity and advancing on seismic hazard forecasting and mitigation.

This study is focused on the modeling of the seismic response in a supercritical geothermal system subjected to a long-term cold and isothermal re-injection during 20 years of exploitation. The modeling aims to assess the usability of seismic-methods for monitoring supercritical geothermal reservoir. We use a synthetic data set for the analysis of the seismic properties of the reservoir: pressure and temperature evolution is derived from a previous numerical study of a two-dimensional supercritical reservoir with pure water as the pore fluid. We calculate the related variations in time of the seismic properties of the reservoir saturated-rock formation using the Burgers–Gassmann mechanical model to evaluate the effects of high temperature on the rock frame, and to account for fluid-properties variations. We observe that, at the analyzed pressure and temperature conditions, the seismic properties of the reservoir formation are mainly determined by the thermophysical characteristics of the pore fluid. During the long-term cold re-injection we observe a decrease in the compressional seismic velocity in the cooled area near the injection well, with a radius that increases in time. We use a 2D full-waveform propagation algorithm based on the Burgers–Gassmann model to calculate synthetic signals in a single-well acquisition layout, with a time step of half year. We observe that in the cool injection scenario the changes in the anomalous area can be seismically monitored, while in the case of isothermal injection, changes due to the re-injection are not seismically appreciable.

The papers in this special section focus on model predictive control (MPC) in energy conversion systems. MPC refers to a broad range of control strategies that make explicit use of a model of the system/device to be controlled optimally. In order to obtain the optimal control signal (or sequence of control signals), MPC optimizes a certain cost function at regular intervals. Due to its unique capabilities to deal with constraints on actuators and system states as well as its theoretical basis, MPC has been widely received and successfully used for many decades, mostly for control of slow industrial plants. However, with continuous advances of control theory and increasing computational capabilities of modern microprocessors, this control strategy has recently became a technically feasible solution for control of energy conversion systems that operate at much faster times scales.

Superhot geothermal environments with temperatures of approximately 400–500 °C at depths of approximately 2–4 km are attracting attention as new kind of geothermal resource. In order to effectively exploit the superhot geothermal resource through the creation of enhanced geothermal systems (superhot EGSs), hydraulic fracturing is a promising technique. Laboratory-scale hydraulic fracturing experiments of granite have recently demonstrated the formation of a dense network of permeable fractures throughout the entire rock body, referred to as a cloud-fracture network, at or near the supercritical temperature for water. Although the process has been presumed to involve continuous infiltration of low-viscosity water into preexisting microfractures followed by creation and merger of the subsequent fractures, a plausible criterion for cloud-fracture network formation is yet to be clarified. The applicability of the Griffith failure criterion is supported by hydraulic fracturing experiments with acoustic emission measurements of granite at 400 °C under true triaxial stress and at 450 °C under conventional triaxial stress. The present study provides, for the first time, a theoretical basis required to establish the procedure for hydraulic fracturing in the superhot EGS.

Developing high-enthalpy geothermal systems requires a sufficiently permeable formation to extract energy through fluid circulation. Injection experiments above water’s critical point have shown that fluid flow can generate a network of highly conductive tensile cracks. However, what remains unclear is the role played by fluid and solid rheology on the formation of a dense crack network. The decrease of fluid viscosity with temperature and the thermally activated visco-plasticity in rock are expected to change the deformation mechanisms and could prevent the formation of fractures. To isolate the solid rheological effects from the fluid ones and the associated poromechanics, we devise a hydro-fracture experimental program in a non-porous material, polymethyl methacrylate (PMMA). In the brittle regime, we observe rotating cracks and complex fracture patterns if a non-uniform stress distribution is introduced in the samples. We observe an increase of ductility with temperature, hampering the propagation of hydraulic fractures close to the glass transition temperature of PMMA, which acts as a limit for brittle fracture propagation. Above the glass transition temperature, acoustic emission energy drops of several orders of magnitude. Our findings provide a helpful guidance for future studies of hydro-fracturing of supercritical geothermal systems.

Supercritical/superhot geothermal success depends on successful drilling. However, wellbore stability in supercritical environments has not been investigated because imposing sufficient stress on high-temperature granite with true triaxial loading is difficult. We conducted wellbore failure experiments on 200–450 °C granite under true triaxial stress, including deformation and acoustic emission measurements, and post-experiment thin section observations. Wellbore failure initiated at stress states consistent with existing brittle failure criterion at the studied temperatures. Using breakout geometry for in situ stress estimation may be difficult as shear failure propagation is suppressed at high temperatures; however, boreholes may be inherently stable in high-temperature environments.

Understanding poromechanical response to injection/pumping into subsurface formations is crucial to assess the potential risk of induced seismicity. Analytical solutions facilitate the parametric space analysis of complex problems involved in geo-energy and geoengineering applications. Yet, as the complexity of the problems increases, it becomes necessary to verify the analytical solutions against numerical ones. Here, we verify an analytical solution to poroelastic stress changes induced by pressurization/depletion of a reservoir intersected by a fault that can be either permeable or impermeable. In particular, we evaluate the poroelastic stress changes in a pressurized reservoir and its surrounding, focusing on the displaced fault, and we make a detailed comparison between results from our analytical solution and numerical simulations with CODE_BRIGHT. The comparison shows that the analytical results are in good agreement with the numerical ones, which confirms the accuracy and correctness of the analytical solution. The proposed solution represents a valid and useful tool in geo-energy related projects.

With the urgent necessity of geo-energy resources to achieve carbon neutrality, fluid injection and production in the fractured media will significantly increase. Applications such as enhanced geothermal systems, geologic carbon storage, and subsurface energy storage involve pressure, temperature, and stress changes that affect fracture stability and may induce microseismicity. To eventually have the ability to control induced seismicity, it is first necessary to understand its triggering mechanisms. To this end, we perform coupled thermo-hydro-mechanical (THM) simulations of cold water injection and production into a rock containing two fracture sets perpendicular between them. The permeability of fractures being four orders of magnitude higher than the one of the rock matrix leads to preferential pressure and cooling advancement, which induce stress changes that affect fracture stability. We find that the fracture set that is oriented favorably to undergo shear slip in the considered stress regime becomes critically stressed, inducing microseismicity. In contrast, the fracture set that is not favorably oriented for shear remains stable. These results contrast with those obtained for an equivalent porous media that does not explicitly include fractures in the model, which fails to reproduce the direction-dependent stability of fractures present in the subsurface. We contend that fractures should be directly embedded in the numerical models when inhomogeneities are of the spatial scale of the reservoir to enable reproducing the THM coupled processes that may lead to induced microseismicity.

With the urgent necessity of geo-energy resources to achieve carbon neutrality, fluid injection and production in the fractured media will significantly increase. Applications such as enhanced geothermal systems, geologic carbon storage, and subsurface energy storage involve pressure, temperature, and stress changes that affect fracture stability and may induce microseismicity. To eventually have the ability to control induced seismicity, it is first necessary to understand its triggering mechanisms. To this end, we perform coupled thermo-hydro-mechanical (THM) simulations of cold water injection and production into a rock containing two fracture sets perpendicular between them. The permeability of fractures being four orders of magnitude higher than the one of the rock matrix leads to preferential pressure and cooling advancement, which induce stress changes that affect fracture stability. We find that the fracture set that is oriented favorably to undergo shear slip in the considered stress regime becomes critically stressed, inducing microseismicity. In contrast, the fracture set that is not favorably oriented for shear remains stable. These results contrast with those obtained for an equivalent porous media that does not explicitly include fractures in the model, which fails to reproduce the direction-dependent stability of fractures present in the subsurface. We contend that fractures should be directly embedded in the numerical models when inhomogeneities are of the spatial scale of the reservoir to enable reproducing the THM coupled processes that may lead to induced microseismicity.

Geoenergy and geoengineering applications usually involve fluid injection into and production from fractured media. Accounting for fractures is important because of the strong poromechanical coupling that ties pore pressure changes and deformation. A possible approach to the problem uses equivalent porous media to reduce the computational cost and model complexity instead of explicitly including fractures in the models. We investigate the validity of this simplification by comparing these two approaches. Simulation results show that pore pressure distribution significantly differs between the two approaches even when both are calibrated to predict identical values at the injection and production wells. Additionally, changes in fracture stability are not well captured with the equivalent porous medium. We conclude that explicitly accounting for fractures in numerical models may be necessary under some circumstances to perform reliable coupled thermohydromechanical simulations, which could be used in conjunction with other tools for induced seismicity forecasting.

Displaced faults crossing the reservoir could significantly increase the induced earthquake frequency in geo‐energy projects. Understanding and predicting the stress variation in such cases is essential to minimize the risk of induced seismicity. Here, we adopt the inclusion theory to develop an analytical solution for the stress response to pore pressure variations within the reservoir for both permeable and impermeable faults with offset ranging from zero to the reservoir thickness. By analyzing fault stability changes due to reservoir pressurization/depletion under different scenarios, we find that (1) the induced seismicity potential of impermeable faults is always larger than that of permeable faults under any initial and injection conditions—the maximum size of the fault undergoing failure is 3–5 times larger for impermeable than for permeable faults; (2) stress concentration at the corners results in the occurrence of reversed slip in normal faults with a normal faulting stress regime; (3) while fault offset has no impact on the slip potential for impermeable faults, the slip potential increases with the offset for permeable faults, which indicates that non‐displaced permeable faults constitute a safer choice for site selection; (4) an impermeable fault would rupture at a lower deviatoric stress, and at a smaller pressure buildup than a permeable one; and (5) the induced seismicity potential is overestimated and the injectivity underestimated if the stress arching (i.e., the poromechanical coupling) is neglected. This analytical solution is a useful tool for site selection and for supporting decision making during the lifetime of geo‐energy projects.

The Pohang earthquake is the largest seismic event induced by any enhanced geothermal system (EGS) project and occurred approximately two months after hydraulic stimulation was completed. Although it is now commonly accepted that the earthquake was induced by high-pressure hydraulic stimulation, which activated a mature fault, the detailed triggering processes and mechanisms remain under debate. To shed light into them, we first make a comparative analysis on the relative likelihood of the several fault planes and in-situ stress states that have been proposed, which present a wide range of values, based on the linear Mohr-Coulomb criterion. From this analysis, we propose two likely oblique-slip faulting patterns to analyze the problem of induced seismicity: a reverse faulting pattern with a strike-slip component (S-RF), which involves a reverse fault being in a three dimensional (3D) reverse faulting stress field; and a strike-slip faulting pattern with a reverse component (R-SS), which considers a strike-slip fault being in a 3D strike-slip faulting stress field. We then apply two analytical solutions to evaluate the coupled hydro-mechanical responses in the quasi-expanding reservoir at the instance of the mainshock for both fault slip patterns. We also perform a parametric space analysis to analyze the effect of the uncertainty in the geological properties on induced seismicity. Following this result, we carry out the Monte Carlo simulations to assess the probability of inducing the Pohang earthquake. From our analyses, we find that the pressure changes and stress variations caused by fluid injection can induce fault reactivation for both patterns, being the R-SS pattern more critical than the S-RF pattern. The probabilities of inducing a felt earthquake (Mw>3.0) and a Mw5.5 earthquakes for the former reach to ~15% and ~10%, respectively. Parametric space analysis shows that the magnitude of in-situ stress and the rock properties are playing a more significant rol

Geo-energy and geo-engineering applications are becoming widespread due to their contribution to achieve net-zero emissions within the next decades. These applications, which include geothermal energy production, geologic carbon storage and hydrogen storage, involve fluid injection into and production from deep geological formation. Discontinuities, i.e., joints, fractures and faults, are ubiquitous in these deep formations, which poses challenges on achieving accurate predictive modeling. We have developed an equivalent fracture layer in a continuum-based approach that yields identical results to the ones of a model that represents a discontinuity with its actual aperture (Zareidarmiyan et al., 2018; 2020). The equivalent fracture layer can have a thickness in the cm scale, upscaling fracture thickness by several orders of magnitude. Such upscaling facilitates discretization of discontinuities while preserving accuracy. Including discontinuities in models is necessary when their spacing is in the order of the reservoir size to capture all the relevant thermo-hydro-mechanical processes induced by fluid injection and/or production (Zareidarmiyan et al., 2021). Equivalent porous media can be calibrated to reproduce fairly well the pressure evolution at the injection and production wells. However, pore pressure and temperature distribution within the fractured media significantly differs from the actual one, which is controlled by discontinuities. Such differences occur at all-time scales. In the short term, pressure diffusion has not enough time to propagate into the rock matrix and thus, pressure changes concentrate along the high-permeable discontinuities. In the long term, pressure diffuses into the rock matrix, equilibrating with the pore pressure in discontinuities, but the pressure distribution still differs from the one of an equivalent porous media because pressure distribution is controlled by the high-permeable network of discontinuities rather than distribu

This dataset includes the input files of the numerical models used in this manuscript for simulating fractures as well as the executable file of the numerical code (CODE_BRIGHT).

The urgency of action to reduce CO2 emissions to mitigate the climate crisis requires to upscale carbon capture and storage (CCS) to the gigaton scale. The injected CO2 not only does induce pressure buildup, but also cooling around the injection wells. Such changes may induce seismicity, which, if felt, could cause nuisance to the local population and damage to infrastructure and could eventually lead to project cancellation. To understand the processes that may induce seismicity in CCS projects, we perform coupled thermo-hydro-mechanical simulations of CO2 injection both in deep sedimentary rock and deep volcanic areas. We have recently proposed to extend CO2 storage to deep volcanic areas because, there, CO2 becomes denser than the resident pore water, which stays in its supercritical state. Simulation results show that CO2 injection in deep sedimentary rock has a low potential of inducing seismicity because 1) the stress state is generally not critically stressed and sedimentary rocks are quite ductile, 2) pressure buildup is easy to control because it becomes practically constant, because of the low viscosity of CO2, after an initial sharp increase at the beginning of injection, and 3) cooling around injection wells induce thermal stresses reduction and a stress redistribution around the cooled region that tightens the caprock, improving its stability in normal faulting stress regimes. In deep volcanic areas, cooling-induced seismicity may dominate after a few years of injection because of the larger temperature contrast and thus, thermal stress reduction, that could reactivate faults located hundreds of meters away from the injection well. Nonetheless, CO2 storage in deep volcanic areas is a new concept that requires further investigation.

Fractures control fluid flow and the coupled geomechanical response of geological media in many geo-engineering applications. For instance, fractures dominate fluid flow and deformation in enhanced geothermal systems, underground radioactive waste repositories, and CO2 storage. Coupled thermo-hydro-mechanical processes in rock masses are a result of perturbations in the pore pressure, as in fluid injection and/or production, and/or temperature, as in cold fluid injection and disposal of radioactive waste. For example, fractures open as a result of pore pressure increase, which simultaneously increases permeability and reduces overpressure. Geo-engineering and geo-energy applications involve a large portion of rock masses that include several fractures. Numerical computations of coupled processes occurring in rock masses while considering a large number of fractures pose several challenges. In this study, we firstly focus on a simple problem to fully understand the hydro-mechanical behavior of a single fracture subjected to a constant injection flow rate. We use the FEM software CODE_BRIGHT, which solves the thermohydro- mechanical governing equations in a fully coupled way. Since standard FEM can solve equations in continuum media, we investigate the behavior of a single fracture by analyzing the hydro-mechanical parameters that control the fracture response in a continuum fashion. However, simulating fractures with the real aperture is not simply feasible, hence, we search the equivalent properties of thicker fractures that are more feasible to be discretized in large-scale models with several fractures.

Geologic carbon storage is needed to reach carbon neutrality and eventually achieve negative emissions. In the classical concept of storing CO2 in deep sedimentary aquifers, supercritical CO2 has a lower density than the resident brine. CO2 is therefore buoyant and the safety and effectiveness of the storage concept rely on the caprock sealing capacity to prevent CO2 leakage. To reduce the risk of CO2 leakage and widen the CO2 storage options, we propose an innovative concept that consists in injecting CO2 in reservoirs where the temperature and pressure of the resident brine are above the critical point ( 373.95 ºC and 22.064 MPa for pure water). At such conditions, which can be found at depths between 3 to 5 km in volcanic areas, CO2 is denser than the resident water and thus, sinks. The sinking tendency reduces the risk of CO2 leakage to the surface even in case of damaged or absent caprock. CO2 storage in supercritical reservoirs can potentially become an additional option to the existing storage concepts aimed at significantly reduce CO2 emissions. We estimate that every 100 wells drilled into supercritical reservoirs could store between 50 to 500 Mt/yr of CO2.