Hydraulic Effects Research Articles

Effectiveness and impact factors of passive convergence-permeable reactive barrier (PC-PRB): Insights from tracer simulation study

Passive convergence-permeable reactive barrier (PC-PRB) represents a green and sustainable technology for in-situ remediation of contaminated groundwater. A laboratory-scale PC-PRB tracer simulation system was established to quantify its contaminant plume capture performance using image analysis method. Results indicate that PC-PRB captures the plume 65% wider than C-PRB, which means that fewer PRB sizes and materials volume would be necessary to treat an equivalent contaminated plume. This improvement is due to a significant drawdown within the PC-PRB's passive well, known as the passive hydraulic decompression-convergent flow effect. We further evaluated the effects of water pipe length, hydraulic gradient, and media particle size on PC-PRB's plume capture performance. Results indicate that an increased water pipe length enhances the PC-PRB's plume capture capacity due to greater well drawdown. PC-PRB not only captures the plume but also acts as a hydraulic barrier. The retardation effect of PC-PRB on plume migration increases with water pipe length. Conversely, both hydraulic gradient and media particle size impact the plume capture capacity of PC-PRB by modifying groundwater flow velocity and pollutant dispersion. An increase in either hydraulic gradient or media particle size decreases the plume capture performance of PC-PRB. Therefore, PC-PRB technology may be more effective in contaminated sites characterized by low hydraulic gradients and permeability. Overall, PC-PRB demonstrates significant effectiveness in enhancing plume capture performance, which can notably reduce remediation costs and environmental footprint, broadening its application scope.

Multi-Task Learning Network-Based Prediction of Hydraulic Fracturing Effects in Horizontal Wells Within the Ordos Yanchang Formation Tight Reservoir

Accurate prediction of fracture volume and morphology in horizontal wells is essential for optimizing reservoir development. Traditional methods struggle to capture the intricate relationships between fracturing effects, geological variables, and operational factors, leading to reduced prediction accuracy. To address these limitations, this paper introduces a multi-task prediction model designed to forecast fracturing outcomes. The model is based on a comprehensive dataset derived from fracturing simulations within the Long 4 + 5 and Long 6 reservoirs, incorporating both operational and geological factors. Pearson correlation analysis was conducted to assess the relationships between these factors, ranking them according to their influence on fracturing performance. The results reveal that operational variables predominantly affect Stimulated Reservoir Volume (SRV), while geological variables exert a stronger influence on fracture morphology. Key operational parameters impacting fracturing performance include fracturing fluid volume, total fluid volume, pre-fluid volume, construction displacement, fracturing fluid viscosity, and sand ratio. Geological factors affecting fracture morphology include vertical stress, minimum horizontal principal stress, maximum horizontal principal stress, and layer thickness. A multi-task prediction model was developed using random forest (RF) and particle swarm optimization (PSO) methodologies. The model independently predicts SRV and fracture morphology, achieving an R2 value of 0.981 for fracture volume predictions, with an average error reduced to 1.644%. Additionally, the model’s fracture morphology classification accuracy reaches 93.36%, outperforming alternative models and demonstrating strong predictive capabilities. This model offers a valuable tool for improving the precision of fracturing effect predictions, making it a critical asset for reservoir development optimization.

Three-dimensional numerical modeling of soil-roots system based on X-ray computed tomography: Hydraulic effects study

Vegetation roots enhance soil stability by influencing saturation and pore structure, playing a pivotal role in stabilizing slopes, reducing erosion, and enhancing soil structure. However, current research on the hydraulic effects of roots on soil remains relatively limited. The micro-mechanisms of vegetation's impact on soil and the macro-level connections are not yet fully understood, which poses a challenge to the modeling of root-soil system. This study develops a three-dimensional (3D) finite element model of root-soil composites based on root computed tomography (CT) images and experimental results. Four different groups are modeled, including the rootless group, and those with Festuca arundinacea (FA) roots at various growth stages. The simulation results show that the saturation in the shallow layers significantly decreases in root-soil composite groups, and the rhizosphere water content is lower than that away from the roots, resulting in a net water flux toward the roots. The influence range of roots on suction is gradually amplified with increasing root growth process and root water uptake time. Higher levels of root development result in a stronger overall water uptake effect, leading to a more pronounced decrease in saturation. Closer proximity to the surface roots results in a more rapid increase in soil suction. Compared with one-dimensional root water uptake models, this model considers the effects of spatial heterogeneity of root structures on soil, which provides a comprehensive modeling basis for studying the effect of root system on soil.

Developmental characteristics of vertical natural fracture in low-permeability oil sandstones and its influence on hydraulic fracture propagation

Vertical natural fractures (NFs) are prevalent in low-permeability sandstone reservoirs. Presently, the impact of NFs on the extension of hydraulic fractures (HFs) remains partially unveiled, which restricts the scientific development of strategies for low-permeability, fractured oil sandstones. In this study, taking the oil sandstone of the He-3 Member, Hetaoyuan Formation, southeastern Biyang Depression as an example, we conducted a comprehensive investigation into the factors influencing vertical fracture development and the interaction between natural and hydraulic fractures. The cohesive unit simulations indicate that geostress is the principal factor influencing HF expansion, more so than NFs, with this influence intensifying as natural fracture density increases. As natural fracture density grows, the potential for two sets of conjugate natural fractures to form short HFs arises, which are limited in expansion scope, suggesting a need to reduce well spacing accordingly. Conversely, areas with a single set of NFs are more prone to developing longer HFs, warranting an increase in well spacing to avoid water channeling. High natural fracture densities may constrain the effectiveness of HFs. In fractured reservoirs with a 10 MPa horizontal stress difference, the length of HFs is 1.52 times that of HFs with 0 MPa and 5 MPa differences. However, the hydraulic fracture effectiveness index (FE) of the latter is 1.74 times higher than the former. For fractured reservoirs, the expansion capacity of HF length within a 5 MPa horizontal stress difference remains relatively stable; beyond this threshold, the expansion capacity increases with the growing horizontal stress difference, and the fracturing effect eventually deteriorates. Furthermore, as the strength of NFs escalates, the length and modified area of HFs initially decrease significantly before stabilizing. The complexity and FE value of HFs formed under strong natural fracture conditions are heightened, indicating a more effective fracturing outcome.

A moving target: trade-offs between maximizing carbon and minimizing hydraulic stress for plants in a changing climate.

Observational evidence indicates that tree leaf area may acclimate in response to changes in water availability to alleviate hydraulic stress. However, the underlying mechanisms driving leaf area changes and consequences of different leaf area allocation strategies remain unknown. Here, we use a trait-based hydraulically enabled tree model with two endmember leaf area allocation strategies, aimed at either maximizing carbon gain or moderating hydraulic stress. We examined the impacts of these strategies on future plant stress and productivity. Allocating leaf area to maximize carbon gain increased productivity with high CO2, but systematically increased hydraulic stress. Following an allocation strategy to avoid increased future hydraulic stress missed out on 26% of the potential future net primary productivity in some geographies. Both endmember leaf area allocation strategies resulted in leaf area decreases under future climate scenarios, contrary to Earth system model (ESM) predictions. Leaf area acclimation to avoid increased hydraulic stress (and potentially the risk of accelerated mortality) was possible, but led to reduced carbon gain. Accounting for plant hydraulic effects on canopy acclimation in ESMs could limit or reverse current projections of future increases in leaf area, with consequences for the carbon and water cycles, and surface energy budgets.

The role of Nature-Based Solutions for the water flow management in a Mediterranean urban area

Due to climate change and rapid urban sprawl, central Mediterranean regions are subjected to short but intensive storm events resulting in a significant increase of flow rates and runoff volumes in low-lying coastal urban areas. Within the framework of green urban infrastructures (GUIs), a suitable combination of Nature-Based Solutions (NBS) with traditional grey infrastructures should be adopted to mitigate flood risk effects in urban and sub-urban areas contributing at the same time to achieve multiple benefits for both the environment and the community. The aim of this study is (i) to evaluate flood hazard maps for identifying the areas within a Sicilian hydrological river basin (Toscano catchment) with a high risk of flooding by implementing the HEC-RAS model at catchment scale; (ii) to quantify the peak flow and floodplain area reduction; (iii) to assess the effectiveness of small-scale NBS (green roofs, porous pavements, rain gardens and rain barrel), in terms of peak flow and runoff volume reductions, at urban block scale by using the EPA SWMM model Model simulations are performed integrating the hydraulic (HEC-RAS) and hydrological (EPA SWMM) models for return periods of 10, 50 and 200 years. The results showed that the estimated peak flow (m3 s−1) obtained from the simulations performed at catchment scale for each T in the current scenario (without NBS) using HEC-RAS and EPA SWMM models are very close to each other (R2 = 0.99). In addition, the utopian scenario simulation showed the HEC-RAS model sensitivity to CN calibration achieving a peak flow reduction up to about 60% with the floodplain area decreasing up to about 17%. Finally, the model EPA SWMM shows its sensitivity to NBS implementation at urban block scale with a peak flow reduction up to about 16% and a runoff volume (mm) reduction up to about 24%. These reductions decrease as T increases with a higher NBS mitigation effects for the lowest T. The results highlighted that the integration of NBS in urban areas could have hydrological and hydraulic positive effects, particularly in terms of peak flow and runoff volume reduction. Furthermore, the results suggest that small-scale NBS have a potential to be effective to smaller rainfall events, but a combination with large-scale NBS is necessary to cope with extreme events.

Optimal Coordinated Operation for Hydro–Wind Power System

The intermittent and stochastic characteristics of wind power pose a higher demand on the complementarity of hydropower. Studying the optimal coordinated operation of hydro–wind power systems has become an extremely effective way to create safe and efficient systems. This paper aims to study the optimal coordinated operation of a hybrid power system based on a newly established Simulink model. The analysis of the optimal coordinated operation undergoes two simulation steps, including the optimization of the complementary mode and the optimization of capacity allocation. The method of multiple complementary indicators is adopted to enable the optimization analysis. The results from the complementary analysis show that the hydraulic tracing effect obviously mitigates operational risks and reduces power losses under adverse wind speeds. The results from the analysis of capacity allocation also show that the marginal permeation of installed wind capacity will not exceed 250 MW for a 100 MW hydropower plant under random wind speeds. These simulation results are obtained based on the consideration of some real application scenarios, which help power plants to make the optimal operation plan with a high efficiency of wind energy and high hydro flexibility.

Development and prospect of acoustic reflection imaging logging processing and interpretation method

Acoustic reflection imaging logging technology can detect and evaluate the development of reflection anomalies, such as fractures, caves and faults, within a range of tens of meters from the wellbore, greatly expanding the application scope of well logging technology. This article reviews the development history of the technology and focuses on introducing key methods, software, and on-site applications of acoustic reflection imaging logging technology. Based on the analyses of major challenges faced by existing technologies, and in conjunction with the practical production requirements of oilfields, the further development directions of acoustic reflection imaging logging are proposed. Following the current approach that utilizes the reflection coefficients, derived from the computation of acoustic slowness and density, to perform seismic inversion constrained by well logging, the next frontier is to directly establish the forward and inverse relationships between the downhole measured reflection waves and the surface seismic reflection waves. It is essential to advance research in imaging of fractures within shale reservoirs, the assessment of hydraulic fracturing effectiveness, the study of geosteering while drilling, and the innovation in instruments of acoustic reflection imaging logging technology.

Multi-fracture growth behavior during TPDF in a horizontal well of multi-clustered perforations: An experimental research

Temporary plugging and diverting fracturing (TPDF), involving inner-fracture temporary plugging (IFTP) and inner-stage temporary plugging (ISTP), has been proposed as a widely applied technique in China, for promoting the uniform initiation and propagation of multi-clustered hydraulic fractures (HFs) in a horizontal well of the shale oil/gas reservoirs. However, how the key plugging parameters controlling the multi-fracture growth and the pumping pressure response during TPDF in shale with dense bedding planes (BPs) and natural fractures (NFs) is still unclear, which limits the optimization of TPDF scheme. In this paper, a series of TPDF simulation experiments within a stage of multi-cluster in a horizontal well were carried out on outcrops of Longmaxi Formation shale using a large-scale true tri-axial fracturing simulation system, combined with the acoustic emission (AE) monitor and computed tomography (CT) scanning techniques. Each experiment was divided into three stages, including the conventional fracturing (CF), IFTP and ISTP. Multi-fracture initiation and propagation behavior, and the dominant controlling parameters were examined, containing the particle sizes, concentration of temporary plugging agent (TPA), and cluster number. The results showed that the number of transverse HFs (THFs) and the overall complexity of fracture morphology increase with the increase in TPA concentration and perforation cluster number. Obviously, the required concentration of TPA is positively correlated with the cluster number. Higher peak values and continuous fluctuations of pumping pressure during TPDF may indicate the creation of diversion fractures. The creation of standard THFs during CF is favorable to the creation of diversion fractures during TPDF. Moreover, the activation of BPs nearby the wellbore during CF is unfavorable to the subsequent pressure buildup during TPDF, resulting in poor plugging and diverting effect. Notably, under the strike-slip fault stress regime, the diversion of THFs is not likely during IFTP, which is similar as the results of ISTP to initiate mainly the un-initiated or under-propagated perforation clusters. Three typical pressure curve types during TPDF can be summarized to briefly identify the hydraulic fracture diversion effects, including good (multiple branches or/and THFs can be newly created), fair (HF initiation along the slightly opened BPs and then activating the NFs), and bad (HF initiation along the largely opened BPs and then connecting with the NFs).

Hydro-pedotransfer functions: a roadmap for future development

Abstract. Hydro-pedotransfer functions (PTFs) relate easy-to-measure and readily available soil information to soil hydraulic properties (SHPs) for applications in a wide range of process-based and empirical models, thereby enabling the assessment of soil hydraulic effects on hydrological, biogeochemical, and ecological processes. At least more than 4 decades of research have been invested to derive such relationships. However, while models, methods, data storage capacity, and computational efficiency have advanced, there are fundamental concerns related to the scope and adequacy of current PTFs, particularly when applied to parameterise models used at the field scale and beyond. Most of the PTF development process has focused on refining and advancing the regression methods, while fundamental aspects have remained largely unconsidered. Most soil systems are not represented in PTFs, which have been built mostly for agricultural soils in temperate climates. Thus, existing PTFs largely ignore how parent material, vegetation, land use, and climate affect processes that shape SHPs. The PTFs used to parameterise the Richards–Richardson equation are mostly limited to predicting parameters of the van Genuchten–Mualem soil hydraulic functions, despite sufficient evidence demonstrating their shortcomings. Another fundamental issue relates to the diverging scales of derivation and application, whereby PTFs are derived based on laboratory measurements while often being applied at the field to regional scales. Scaling, modulation, and constraining strategies exist to alleviate some of these shortcomings in the mismatch between scales. These aspects are addressed here in a joint effort by the members of the International Soil Modelling Consortium (ISMC) Pedotransfer Functions Working Group with the aim of systematising PTF research and providing a roadmap guiding both PTF development and use. We close with a 10-point catalogue for funders and researchers to guide review processes and research.

Research on the Influencing Factors of Pulsed Hydraulic Fracturing Effects in Hot Dry Rock Based on Numerical Simulation

Geothermal energy, representing one of the five principal non-carbon-based renewable resources, is crucial in the global energy transition and in mitigating greenhouse gas emissions. Hot Dry Rock (HDR) reservoirs, rich in geothermal resources, predominantly utilize hydraulic fracturing, the most extensively researched and applied technology. However, fracturing these robust HDR formations poses significant challenges compared to traditional hydraulic fracturing in sedimentary rocks in the oil and gas industry. Cyclic pulse fracturing, an innovative mode of fracturing, has received limited academic attention, particularly regarding its permeability enhancement mechanism under varying thermal and pressure conditions, which remains largely unexplored. Building on prior laboratory experiments, this study employs the pore pressure cohesive zone model within ABAQUS software to elucidate the initiation and expansion of hydraulic fractures. Numerical simulations investigated the influence of critical parameters such as pulse pattern, temperature, geostress differential, and confining pressure on fracture propagation. The findings indicate that cyclic pulse hydraulic fracturing can significantly reduce the breakdown pressure in HDR, with reductions up to 37.68% under certain conditions. Notably, at constant amplitude, increased frequency exacerbates damage to hot dry rocks; conversely, at constant frequency, higher amplitudes result in greater damage. Additionally, pulse hydraulic fracturing improves the fracturing process, yielding a more intricate fracture network. In HDR pulse hydraulic fracturing, the temperature disparity between the fracturing fluid and the rock markedly impacts the breakdown pressure. Cold water interacting with a high-temperature geo-thermal reservoir triggers a thermal shock effect, diminishing initiation pressure and expediting fracture development and expansion. The impact of geostress differential and confining pressure on pulse hydraulic fracturing is complex, influencing not only the breakdown pressure but also the direction and extent of fracture expansion.

Sensitivity analysis of hydraulic erosion and calibration of the erosion coefficient

Hydraulic erosion may pose a threat to the safety and sustainability of geo-related infrastructure, yet quantifying the intricate process of hydraulic erosion still poses a significant scientific and technical challenge. One important step in meeting this challenge is the formulation of a hydraulic erosion model with the erosion coefficient as a central controlling parameter. Calibration of the erosion coefficient (or rate) remains one of the main obstacles to improving predictive modelling, particularly in scenarios lacking long-term laboratory test data. In this study, sensitivity analysis of the key erosion indicators on the parameters controlling hydraulic erosion is conducted. A novel calibration method for the erosion coefficient is presented based on sensitivity analysis. After validating against simulation results and laboratory test findings, the proposed calibration method is applied to a hypothetical long-term hydraulic erosion case. The results show that the maximum hydraulic erosion time is sensitive to all considered parameters (erosion coefficient, initial fraction of fluidized solid particle, initial porosity and maximum porosity), while the erosion curve shape is only sensitive to the initial porosity and the maximum porosity. The validation by existing simulation results shows that the proposed calibration method is robust and internally consistent. The validation by experimental results indicates that the proposed calibration method also has high external validity. Finally, the proposed calibration method is applied to hypothetical long-term erosion in a grouted area. The results show that the hydraulic erosion effect in the grouted area becomes increasingly severe over time. This study contributes toward a more efficient calibration of the erosion coefficient, especially for scenarios in the absence of testing porosity evolution data. The research outcome provides a theoretical foundation for the safety assessment and sustainability analysis of geotechnical structures that are subject to hydraulic erosion.

Study on the hydraulic effect of Tesla valve structure on the end roadway of abandoned coal mine pumped storage

The use of abandoned mine for pumped storage has garnered significant attention as a novel energy storage technology. The hydraulics of utilizing underground reservoirs constructed in mine roadways represent a key issue for the application of abandoned mines in pumped storage. This study focuses on the practical situation of the Longdong Coal Mine in Jiangsu Province, China. By employing numerical simulation methods, the research investigates the phenomenon of water wave reflection at the end of the roadway in an abandoned mine pumped storage station, as well as the improvement effect of the Tesla valve structure on the reflected water waves. It was found that under the condition of the hydraulic turbine, the reflected wave height at the end of the roadway could reach 1–1.5 times that before reflection. The Tesla valve structure was found to be an effective means of reducing the water level height at the end of the roadway. The average water level was reduced by 0.55 m and 0.35 m under the two flow rates of 1 m/s and 1.4 m/s, respectively. Under the pump condition, the Tesla valve structure has little obstruction to the reverse flow of water. This study has to a certain extent addressed the issue of excessive wave height from water wave reflections at the end of the roadway, thereby enhancing the operational stability of the abandoned mine pumped storage station.

Analysis of Hydraulic Permeability Enhancement Effect Based on an Experimental System of Highly Pressurized Water Invasion and Gas Seepage

Analysis of Hydraulic Permeability Enhancement Effect Based on an Experimental System of Highly Pressurized Water Invasion and Gas Seepage

Nonlinear modelling and design of synergetic controllers for single penstock multi-machine hydropower system

The existence of a shared pipeline in a multi-machine system can lead to hydraulic coupling effects between units. It increases the difficulty of controlling hydroelectric units and affects the stability of the power system. This paper refines the model of the hydroelectric generator unit and builds a nonlinear model of a hydro-generator unit with the single penstock multi-machine system. The synergetic control theory was introduced, and the governor and excitation system controllers were designed separately. A joint synergistic controller is obtained by analyzing the two systems' synergistic factors and controlled characteristics. This controller realizes the joint control of the excitation and governor system. The simulation selected a proportion-integral-derivative (PID) controller with optimized parameters, synergistic governor controller (SEC), and synergistic excitation controller (SGC) for comparison to verify the effectiveness of the proposed method. The results indicate that the proposed control method exhibits competent control effects in the single penstock multi-machine system. It can reduce the impact of hydraulic coupling, shorten the adjusting time, and ensure the fast and stable operation of the system. In addition, the values of system time parameters and synergetic control parameters are analyzed separately to provide a reference for achieving optimal control.

Fracture propagation and evaluation of dual wells, multi-fracturing, and split-time in Fuyu oil shale

Reservoir stimulation is crucial for in-situ exploitation, it can promote a fracture network and increase the heat transfer area. Therefore, it directly affects heat injection and products transportation efficiencies. Conventional reservoir stimulation techniques, such as hydraulic fracturing are widely used. However, hydraulic fracturing in a vertical well tends to generate simple fractures that are unfavorable for heat transfer, and real-time fracture propagation is difficult to monitor, thus failing to precisely control the hydraulic fracturing scale. In addition, there are few qualitative and quantitative criteria in reservoir-scale fracture evaluations for interpreting the overall hydraulic fracturing effect. Consequently, in this study, dual wells, multi-fracturing, and split-time technology (DMS) were designed and conducted based on microseismic monitoring in field experiment to find real-time fracture propagation. Furthermore, based on Hugot's research on connecting microseismic events by spatiotemporal sequences, we proposed a step index and path intensity considering microseismic event intensities to evaluate the effect on hydraulic fracturing. The results showed that a three-dimensional fracturing zone with a 60 × 30 × 8 m length, width, and height was generated at a 476–484 m depth, which corresponded to the designed hydraulic fracturing and facilitated heat transfer and product migration. Higher pump pressure and rate harmed hydraulic fracturing, blocking proppant migration during which the FK1-4 coefficient of viscosity reached 70 N⋅s/m2, 1.4 times greater than that of FK1-2 and FK1-5 according to Poiseuille's law. The hydraulic fracturing effect in FK1-4 was superior than that in FK1-2 and FK1-5. This study serves as a reference for monitoring oil shale exploitation via in-situ pyrolysis.

Biophysical phenotyping of single-cell based on impedance and application for individualized precision medicine

Single-cell biophysical characterization based on impedance measurement is an advantageous approach due to its label-free, high-efficiency, cost-effective and real-time capability. Biophysical phenotyping can yield timely and rich information on physiological and pathological state of cells for disease diagnosis, drug screening, precision medicine, etc. However, precise measurement on single-cell impedance is challenging, particularly hard to figure out the detailed biophysical parameters of single cell due to coupling and complexity of impedance model. Here, we propose an analytic determination method to decode single-cell electrophysiological parameters (including cell-substrate interface capacitance, cell membrane capacitance, cell membrane conductivity, and cytoplasm conductivity) from the impedances measured at optimized frequencies by using analytic solution rather than spectrum fitting. With this simple and fast analytic solution method, the physiological parameters of single cell in natural adhesion state can be accurately determined in real time. We validate this cell parameter determination method in monitoring the change of cell adhesion under hydraulic effects and exploring electrophysiological differences among MCF-7, HeLa, Huh7, and MDA-MB-231 cell lines. Particularly, we apply the approach to optimize tumor treating fields (TTFields) therapy, realizing individualized precision medicine. Our work provides an accurate and efficient approach for characterizing single-cell biophysical properties with real-time, in-situ, label-free, and less invasive advantages.

Ranking the oil contribution of individual layers in a lacustrine shale oil system based on non-hydrocarbon analysis by FT-ICR MS

Identifying the dominating oil-producing layer(s) within a shaly system, typically characterized by multiple layers with similar properties, is always a critical yet formidable task, as the oil component disparities among these closely adjacent layers are too minor to be resolved by the traditional geochemical fingerprints. This challenge is now likely addressed by high-resolution Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS), which can resolve thousands of non-hydrocarbons that could serve as new fingerprints. Taking a typical shaly system in the Ordos Basin in China as an example, the specific proportions of non-hydrocarbon compounds from the retained petroleum of different source rock layers (rock extracts) and the produced oil at the wellhead were identified by FT-ICR MS. Their compositional similarity was calculated using a multidimensional scaling (MDS) method, and the layers hosting the retained petroleum with higher compositional similarity to the produced oils are considered to be the main contributors to oil production. The results show that the main producing layers identified by FT-ICR MS differ from those proposed based on traditional fingerprints like the Rock-Eval parameters. A typical example is that the thick low-TOC shales, conventionally proposed to be unessential to oil production, seem to have a similar contribution, if not higher, to their thick silty counterparts. This divergence may be attributed to the fact that the conventional fingerprints primarily rely on the rock extracts from a vertical well section, which may only represent a limited lateral area, while the non-hydrocarbon similarity approach involving the produced oil appears to be more realistic, as it can consider the engineering processes, like the horizontal well track and the hydraulic fracturing effects. The current approach provides a novel route for identifying the dominating producing layer(s) in a shale oil system, which may have extensive potential for optimizing the production strategy of shale oil wells.

Scaling analysis of nuclear power plant (APR1400) utilizing ATLAS integral effect test result of A5.1 (Counterpart test for LSTF 1% cold-leg break LOCA)

ATLAS is the thermal hydraulic integral effect test loop that can simulate the same pressure and temperature condition with nuclear power plant. It was designed with a height ratio of 1/2 and a volume ratio of 1/288 with reference to APR1400. The counterpart test against LSTF which was named as A5.1 test was performed within the OECD/NEA ATLAS international joint research project to compare major thermal hydraulic phenomena between two test facilities. The main scenario for the A5.1 test is the LSTF SB-CL-32 test. The SB-CL-32 test is a 1% horizontal small break loss of coolant accident (SBLOCA) at the cold leg with cold leg injection of the emergency core cooling system (ECCS) and accident management (AM) action.From the counterpart test results, the significant differences were found in the viewpoint of the thermal–hydraulic phenomena. It was concluded that the different result were caused by the different design characteristic of each test facility because they referred the different nuclear power plant. Thus, the applicability of the ATLAS test results to its reference nuclear power plant was evaluated by utilizing ATLAS A5.1 test results which was the counterpart test with the LSTF.The transient scenario and initial and boundary conditions of the A5.1 test were adopted to APR1400 after applying scaling ratios of ATLAS. The MARS-KS code was utilized to analyzed thermal hydraulic behaviors of APR1400 and the analysis results were compared with the scaled A5.1 test result. From the result of comparison, it was concluded that the ATLAS test results predicted the thermal hydraulic behavior of the nuclear power plant well. Thus, it was confirmed that ATLAS is a well-designed integral effect test facility which is designed with an appropriate scaling method.

Water Content Evolution in the EDZ of Opalinus Clay: A Methodic Approach for a Comparative Interpretation of Measurements and Modelling

In the Mont Terri Rock Laboratory (Switzerland), an interdisciplinary examination program is carried out to increase knowledge about coupled hydro-mechanical effects in Opalinus Clay, which are of significant interest regarding the stability and integrity of a potential storage facility for high-level radioactive waste. This article focuses on the characterization of the claystone in the near field of excavations and related hydraulic effects due to excavation and ventilation. Electrical resistivity tomography (ERT) is applied to characterize the OPA: Several open fractures correlate with regions of high resistivity values, indicating potential preferential flow paths that are relevant for transport processes. Due to the combined interpretation of ERT long-term monitoring and seasonally repeated nuclear magnetic resonance (NMR) measurements, a relationship between electrical resistivity and water content can be established, resulting also in a time-dependent map of the water content around excavations with different climatic conditions. The statistical interpretation of these measurements indicates the existence of small-scale singularities in contrast to dominating, more homogeneous zones. The presented approach leads to a better process understanding of these heterogeneous near field effects and provides a valuable basis for a pragmatic approach to safety assessment.