scholarly journals Water Infusion on the Stability of Coal Specimen under Different Static Stress Conditions

2020 ◽  
Vol 10 (6) ◽  
pp. 2043
Author(s):  
Zilong Zhou ◽  
Lihai Tan ◽  
Xin Cai
Keyword(s):  
Water Distribution ◽  
Water Saturation ◽  
Axial Stress ◽  
Stress Conditions ◽  
Distribution Model ◽  
Water Infusion ◽  
Instability Point ◽  
Stress Coefficient ◽  
Distribution Rule ◽  
Mining Hazards

Underground coal mines are frequently subjected to water infusion, resulting in many mining hazards. This study investigated the effect of water infusion on the stress and energy evolution characteristics of coal specimens representing isolated pillars under different initial axial stress conditions using the discrete element method. A water infusion distribution model was developed, in which random functions were employed to describe water distribution for the purpose of realizing the dispersion of results for a better reliability. Based on the results, a stress-level classification was presented to evaluate the water effect on pillars’ instability. For the investigated coal specimens, the water weakening effect on stress and energy remains stable when the axial geo-stress on pillars is less than 65% of uniaxial compressive strength (UCS). In contrast, when the axial stress coefficient is greater than 65%, pillars become unstable eventually. A higher axial stress coefficient is more likely to introduce a lower critical instability point of the water saturation coefficient for pillars in the process of water infusion. However, the instability point remains random to some extent for specimens following the same water distribution rule under the identical test condition. Two instability types, which also happened randomly, were observed in the numerical results for damaged coal specimens under different water saturation coefficients and axial geo-stresses, namely free-falling and step-falling.

scholarly journals An Inexact Inventory Theory-Based Water Resources Distribution Model for Yuecheng Reservoir, China

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Meiqin Suo ◽  
Fuhui Du ◽  
Yongping Li ◽  
Tengteng Kong ◽  
Jing Zhang
Keyword(s):  
Water Resources ◽  
Water Distribution ◽  
Water Diversion ◽  
Distribution Model ◽  
Inventory Theory ◽  
Resources Management ◽  
Resources Distribution ◽  
Multiple Uncertainties ◽  
System Benefit ◽  
Decision Alternatives

In this study, an inexact inventory theory-based water resources distribution (IIWRD) method is advanced and applied for solving the problem of water resources distribution from Yuecheng Reservoir to agricultural activities, in the Zhanghe River Basin, China. In the IIWRD model, the techniques of inventory model, inexact two-stage stochastic programming, and interval-fuzzy mathematics programming are integrated. The water diversion problem of Yuecheng Reservoir is handled under multiple uncertainties. Decision alternatives for water resources allocation under different inflow levels with a maximized system benefit and satisfaction degree are provided for water resources management in Yuecheng Reservoir. The results show that the IIWRD model can afford an effective scheme for solving water distribution problems and facilitate specific water diversion of a reservoir for managers under multiple uncertainties and a series of policy scenarios.

Experimental Study on the Saturation Model of Volcanic Rock Based on Fluid Distribution

2021 ◽  
Vol 62 (4) ◽  
pp. 422-433
Author(s):  
Baozhi Pan ◽  
◽  
Weiyi Zhou ◽  
Yuhang Guo ◽  
Zhaowei Si ◽  
...  
Keyword(s):  
Volcanic Rock ◽  
Oil And Gas ◽  
Water Saturation ◽  
Early Stage ◽  
Evaluation Model ◽  
Acoustic Velocity ◽  
Distribution Model ◽  
Fluid Distribution ◽  
Water Drainage ◽  
Gas Reservoirs

A saturation evaluation model suitable for Nanpu volcanic rock formation is established based on the experiment of acoustic velocity changing with saturation during the water drainage process of volcanic rock in the Nanpu area. The experimental data show that in the early stage of water drainage, the fluid distribution in the pores of rock samples satisfies the patchy formula. With the decrease of the sample saturation, the fluid distribution in the pores is more similar to the uniform fluid distribution model. In this paper, combined with the Gassmann-Brie and patchy formula, the calculation equation of Gassmann-Brie-Patchy (G-B-P) saturation is established, and the effect of contact softening is considered. The model can be used to calculate water saturation based on acoustic velocity, which provides a new idea for the quantitative evaluation of volcanic oil and gas reservoirs using seismic and acoustic logging data.

scholarly journals Stress-Testing Framework for Urban Water Systems: A Source to Tap Approach for Stochastic Resilience Assessment

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 154
Author(s):  
Dionysios Nikolopoulos ◽  
Panagiotis Kossieris ◽  
Ioannis Tsoukalas ◽  
Christos Makropoulos
Keyword(s):  
Water Distribution ◽  
Stress Testing ◽  
Water Cycle ◽  
Water System ◽  
Operating Conditions ◽  
Distribution Model ◽  
Generation Model ◽  
Urban Water ◽  
Testing Framework ◽  
Urban Water System

Optimizing the design and operation of an Urban Water System (UWS) faces significant challenges over its lifespan to account for the uncertainties of important stressors that arise from population growth rates, climate change factors, or shifting demand patterns. The analysis of a UWS’s performance across interdependent subsystems benefits from a multi-model approach where different designs are tested against a variety of metrics and in different times scales for each subsystem. In this work, we present a stress-testing framework for UWSs that assesses the system’s resilience, i.e., the degree to which a UWS continues to perform under progressively increasing disturbance (deviation from normal operating conditions). The framework is underpinned by a modeling chain that covers the entire water cycle, in a source-to-tap manner, coupling a water resources management model, a hydraulic water distribution model, and a water demand generation model. An additional stochastic simulation module enables the representation and modeling of uncertainty throughout the water cycle. We demonstrate the framework by “stress-testing” a synthetic UWS case study with an ensemble of scenarios whose parameters are stochastically changing within the UWS simulation timeframe and quantify the uncertainty in the estimation of the system’s resilience.

scholarly journals Apparent Permeability Model for Gas Transport in Multiscale Shale Matrix Coupling Multiple Mechanisms

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6323
Author(s):  
Xiaoping Li ◽  
Shudong Liu ◽  
Ji Li ◽  
Xiaohua Tan ◽  
Yilong Li ◽  
...  
Keyword(s):  
Pore Size ◽  
Water Distribution ◽  
Gas Transport ◽  
Water Saturation ◽  
Gas Permeability ◽  
Apparent Permeability ◽  
Permeability Model ◽  
Proposed Model ◽  
Irreducible Water Saturation ◽  
The Impact

Apparent gas permeability (AGP) is a significantly important parameter for productivity prediction and reservoir simulation. However, the influence of multiscale effect and irreducible water distribution on gas transport is neglected in most of the existing AGP models, which will overestimate gas transport capacity. Therefore, an AGP model coupling multiple mechanisms is established to investigate gas transport in multiscale shale matrix. First, AGP models of organic matrix (ORM) and inorganic matrix (IOM) have been developed respectively, and the AGP model for shale matrix is derived by coupling AGP models for two types of matrix. Multiple effects such as real gas effect, multiscale effect, porous deformation, irreducible water saturation and gas ab-/de-sorption are considered in the proposed model. Second, sensitive analysis indicates that pore size, pressure, porous deformation and irreducible water have significant impact on AGP. Finally, effective pore size distribution (PSD) and AGP under different water saturation of Balic shale sample are obtained based on proposed AGP model. Under comprehensive impact of multiple mechanisms, AGP of shale matrix exhibits shape of approximate “V” as pressure decrease. The presence of irreducible water leads to decrease of AGP. At low water saturation, irreducible water occupies small inorganic pores preferentially, and AGP decreases with small amplitude. The proposed model considers the impact of multiple mechanisms comprehensively, which is more suitable to the actual shale reservoir.

scholarly journals Evaluation of groundwater recharge by rice and crop rotation fields in Kumamoto, Japan

2019 ◽  
Vol 11 (4) ◽  
pp. 1042-1049
Author(s):  
Takehide Hama ◽  
Toshio Fujimi ◽  
Takeo Shima ◽  
Kei Ishida ◽  
Yasunori Kawagoshi ◽  
...  
Keyword(s):  
Groundwater Recharge ◽  
Paddy Field ◽  
Local Governments ◽  
Water Distribution ◽  
Groundwater Resources ◽  
Water Shortage ◽  
Distribution Model ◽  
Drought Risk ◽  
Large Contribution ◽  
Environmental Measures

Abstract In Kumamoto, Japan, about one million people depend for all their water on groundwater resources. Paddy fields and rice farming in the middle river watershed area make a large contribution to the groundwater recharge. In our research, an environmental measure (artificial flooding for groundwater recharge) conducted by local governments is evaluated. Hydrological measurement was conducted in a paddy plot in the area. A simple model of water distribution was developed on the basis of the field measurement. Then, drought risk in the paddy-field district was estimated using the model and GIS data. The results reveal that the fields with a high percolation rate of more than 30 mm/d result in inefficient use of irrigation water although they have large potential for groundwater recharge. In addition, the water distribution model suggests that environmental measures can increase the risk of water shortage in the paddy-field district due to the farmers' careless use of water.

Developing Resource Consumption Insights From Campus-Scale Water Monitoring Infrastructures

2012 ◽  
Author(s):  
Geoff Lyon ◽  
Amip Shah ◽  
Alan McReynolds
Keyword(s):  
Water Consumption ◽  
Distribution System ◽  
Water Distribution ◽  
Distribution Model ◽  
Second Phase ◽  
Water Usage ◽  
Daily Consumption ◽  
Flow Meters ◽  
End Point ◽  
Engineering Changes

Water consumption at many commercial campuses is a significant portion of resource expenditure, often with limited or no visibility into the individual branch or point of use locations, all of which summate to provide utility based reporting and invoicing, mostly on a monthly basis. In this paper, we present a case study where a commercial campus’ water distribution system is being instrumented to obtain a more granular measure of water usage. Measurement granularity is improved both in the time domain, transitioning from monthly to hourly or more frequent reporting, and in the spatial domain with all major end loads and significant branch loads being classified or monitored. Specifically, additional instrumentation is deployed in two distinct phases. The first phase added wireless transducers to the existing utility installed mechanical meters, enabling them to transmit consumption data every quarter hour. The second phase will instrument existing branch flow meters and also insert new flow meters to certain end-point loads and sub-branches. This will enable point or clustered data polling on the order of every few seconds. We also obtain additional information by polling an existing HVAC building management system for water related points of interest. We find that the collection and storage of granular water consumption information has the potential to create a detailed demand-side mapping of water usage on campus; providing data with significantly shortened time periods compared to the use of utility billing alone. We use this information to obtain hourly and daily consumption summaries at the site level and for specific end-load devices. From these results, we have created a hybrid consumption estimation of water consumption at the campus level, which contains a mixture of surveyed estimations and dynamic readings. This model provides improved accuracy and insights when compared to static site survey estimations. Due to the age and complexity of the site, primarily a result of numerous engineering changes over the site’s 60 year lifespan and a lack of detailed historical documentation, further work is ongoing to determine which additional endpoint loads or branched sub-sections we will instrument. We plan to use these additional data points to refine our water distribution model; hoping to accurately map individual buildings, floors and functional areas over time. At present, our site level instrumentation has been beneficial in revealing a number of insights regarding unexpected consumption events, most of which were attributed to scheduled maintenance activities. The ongoing monitoring of individual end-point loads has also highlighted areas of significant demand, which could be prioritized for conservation initiatives, and has shown where systemic adjustments could reduce demand peaking and flatten the flow requirements our campus places on the supplying utility.

scholarly journals Elevation Effect in Urban Water Distribution Model

2018 ◽  
Vol 153 ◽  
pp. 09001
Author(s):  
Rangsan Wannapop ◽  
Thira Jearsiripongkul ◽  
Krit Jiamjiroch
Keyword(s):  
Water Supply ◽  
Water Distribution ◽  
Supply System ◽  
Distribution Model ◽  
Pipeline System ◽  
Urban Water ◽  
Main Pipeline ◽  
Pipe Network ◽  
Pipeline Network ◽  
Water Distribution Model

Metropolitan Waterworks Authority (MWA) is Thailand's national government agency responsible for the supply of water to 3 provinces Bangkok, Nonthaburi and Samut Prakan with more than 2,384.9 km2 of service area and 2,281,058 consumers in the year 2016. Bangkok, which is both the capital and the economic center of the country, is densely populated. Consequently, there is a huge demand for water; MWA has to supply 5.914 million cubic meters of water per day. Because the metropolitan water supply area is a densely populated city, the water supply system is very complex like a spider’s web. For this reason, MWA has adopted EPANET software for its water supply managing tool in the main pipeline system. There are some mistakes in the main pipe network; the elevations of the nodes are not assigned, so there are some errors. In this study, we have assigned elevations for all nodes on the pipeline network based on mean sea level (MSL). After adjusting the elevation of each node, it was found that the new pipeline network has increased the correlation between means to 0.893 from the existing model mean of that is 0.803 of accuracy up 0.09 (11.2%).

scholarly journals Effect of Water Distribution on Spontaneous Imbibition of Tight Rocks: A Fractal Approach

Energies ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 6505
Author(s):  
Haitang Yu ◽  
Qi Li ◽  
Xiangfang Li ◽  
Dong Feng
Keyword(s):  
Porous Media ◽  
Water Distribution ◽  
Water Saturation ◽  
Capillary Tube ◽  
Fractal Theory ◽  
Differential Pressure ◽  
Spontaneous Imbibition ◽  
Equilibrium Time ◽  
Fractal Approach ◽  
Capillary Tube Model

The original water distribution characteristic plays an important role in the fracturing liquid retention in actual tight reservoirs. In this paper, an analytical model was proposed to characterize the water distribution and its effect on the spontaneous imbibition, based on the capillary tube model and fractal theory. Furthermore, the effect of the water film and the non-piston-like front related to the pore size are included in our model. The proposed model was successfully validated with the experimental results of core imbibition tests. Our work demonstrates that water distribution is influenced by displacement pressure and pore structure. For a small differential pressure, the porous media with richer large pores usually possesses a lower water saturation, and this difference will decrease with the increase of differential pressure. Moreover, compared with previous studies, the proposed imbibition model can not only distinguish the valid pores and invalid pores for imbibition but it can also predict the initial imbibition rate and equilibrium time of tight porous media with different water saturation. The results show that the equilibrium time is controlled by the minimum effective pore radius while the initial imbibition rate is mainly controlled by the large pores. Both of these two parameters will decrease with an increase of water saturation; the former is more sensitive to a low water saturation, while the latter decreases more quickly for a middle-high water saturation.

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