Numerical Simulation and Prediction of High Fluorine Groundwater Transport in Zhangye Basin

2012 ◽  
Vol 466-467 ◽  
pp. 36-41
Author(s):  
Yong Hui An ◽  
Shuang Bao Han ◽  
Xi Wu ◽  
Xu Xue Cheng ◽  
Wei Po Liu
Keyword(s):  
Transport Model ◽  
System Response ◽  
Confined Water ◽  
Local Planning ◽  
Deep Groundwater ◽  
Well Completion ◽  
Phreatic Water ◽  
Single Well ◽  
Zhangye Basin ◽  
Exploitation Intensity

Simulate Feflow with finite element method, and establish flow model and solute transport model of high fluorine groundwater area in Zhangye Basin. Predicting groundwater system response under different exploitation scheme, and evaluating the risk of deep low fluorine groundwater polluted by shallow high fluorine groundwater. The results showed that, firstly, the existing exploitation intensity and the increasing exploitation intensity of the local planning would lead to groundwater table descent, for the deep groundwater head is higher than phreatic water in above scheme, the polluted risk of low fluorine freshwater is low. Secondly, low and deep groundwater “cross strata” caused by well completion technology would lead to deep low fluorine freshwater polluted, and the high fluorine polluted area caused by single well is limited, but the polluted risk of low fluorine aquifer is increasing with that confined water head is lower than phreatic water in local concentrated excess exploitation area. Propose the measures and suggestions of the groundwater sustainable utilization.

Power Spectral Density of Nonlinear System Response: The Recursion Method

1993 ◽  
Vol 60 (2) ◽  
pp. 358-365 ◽  
Author(s):  
R. Vale´ry Roy ◽  
P. D. Spanos
Keyword(s):  
Broad Class ◽  
Formal Solution ◽  
Power Series Expansion ◽  
Kolmogorov Equation ◽  
System Response ◽  
Lanczos Algorithm ◽  
Spectral Densities ◽  
Recursion Method ◽  
Approximate Form ◽  
Single Well

Spectral densities of the response of nonlinear systems to white noise excitation are considered. By using a formal solution of the associated Fokker-Planck-Kolmogorov equation, response spectral densities are represented by formal power series expansion for large frequencies. The coefficients of the series, known as the spectral moments, are determined in terms of first-order response statistics. Alternatively, a J-fraction representation of spectral densities can be achieved by using a generalization of the Lanczos algorithm for matrix tridiagonalization, known as the “recursion method.” Sequences of rational approximations of increasing order are obtained. They are used for numerical calculations regarding the single-well and double-well Duffing oscillators, and Van der Pol type oscillators. Digital simulations demonstrate that the proposed approach can be quite reliable over large variations of the system parameters. Further, it is quite versatile as it can be used for the determination of the spectrum of the response of a broad class of randomly excited nonlinear oscillators, with the sole prerequisite being the availability, in exact or approximate form, of the stationary probability density of the response.

scholarly journals Chemical Characteristics and Quality Assessment of Groundwater of Exploited Aquifers in Beijiao Water Source of Yinchuan, China: A Case Study for Drinking, Irrigation, and Industrial Purposes

2015 ◽  
Vol 2015 ◽  
pp. 1-14 ◽  
Author(s):  
Hao Wu ◽  
Jie Chen ◽  
Hui Qian ◽  
Xuedi Zhang
Keyword(s):  
Quality Assessment ◽  
Water Samples ◽  
Coupled Model ◽  
Simple Algorithm ◽  
Water Source ◽  
Human Consumption ◽  
Chemical Characteristics ◽  
Control Mechanisms ◽  
Confined Water ◽  
Phreatic Water

This work is aimed at reviewing the chemical characteristics and evaluation of the quality of exploited groundwater in Beijiao water source of Yinchuan. A coupled model based on osculating value method (OVM) and entropy is proposed to determine the suitability for drinking. Besides, phreatic water and confined water are evaluated for irrigation purposes and industrial purposes, respectively. Piper diagram shows different hydrochemical characteristics between aquifers, which can be explained by the control mechanisms revealed by Gibbs diagram. Chloroalkaline indices and ions relationship indicate that reverse ion exchanges occur in different aquifers. Based on the osculating values, 96% of the phreatic water samples are fit for human consumption, and the confined water can provide quality drinking water. Most of the phreatic water samples have no sodium hazard but have magnesium hazard. All the confined water samples generate mild foaming reaction, and 93% of them are mildly corrosive for boilers. An assessment by OVM without entropy is calculated. Similar results to the coupled model demonstrate that pure OVM is also objective and valid. The simple algorithm turns multicriteria decision-making problems into an integrated index which is just as useful to water quality assessment.

A Cost Effective, Fit-for-Purpose Single Well Producer-Injector Completion Strategy for Improved Recovery of Oil: Case Study in Niger Delta

2016 ◽  
Author(s):  
Pranav Dubey ◽  
Adrian Okpere ◽  
Gideon Sanni ◽  
Ifeanyi Onyeukwu
Keyword(s):  
Data Acquisition ◽  
Oil Recovery ◽  
Niger Delta ◽  
Water Saturation ◽  
Optimized Design ◽  
Production Forecast ◽  
Safety Control ◽  
Well Completion ◽  
Single Well ◽  
Fit For Purpose

ABSTRACT An optimized completion design that addresses gaps in the existing single well Producer-Injector (P-I) concept is presented in this paper. Field development scenarios based on the optimized P-I concept and conventional waterflood were implemented in full-field 3D simulation models. Detailed review of the existing single P-I well concept revealed gaps in the completion design with regards to feasibility of data acquisition, ease of well intervention and well safety/control. The existing design utilizes a Single-String-Single (SSS) design with through-tubing water injection and oil production through annulus, whilst the optimized design is a Two-String-Dual (TSD) incorporating the flexibility of independent injection/production, zonal isolation for interventions & data acquisition and additional safety completion jewelries. A fit-for-purpose reservoir candidate was selected by assessing it's suitability to waterflooding. The reservoir belongs to the paralic sequence of the Agbada Formation of the Niger Delta basin – a sequence of interbedded sandstones and shales. The reservoir is an elongated anticline bounded by W-E oriented faults and exhibiting channelized shoreface sediments. Porosity and permeability ranges are 17-31% and 200mD-2200mD respectively. Shale baffles strongly reduces the influence of the aquifer hence the simulation model is an oil reservoir with weak aquifer completed by the P-I well producing oil and injecting into the aquifer in tandem. Performance of the single P-I well strategy was benchmarked against conventional waterflood patterns to effectively capture the recovery efficiency and production forecast for each scenario. Results from the five-parameter experimental design based on the P-I strategy, indicate Ultimate Oil Recovery is most impacted by horizontal permeability; injection rate, flow barrier transmissibility and vertical permeability with the least influence. Dynamic 3D water saturation maps show the waterflood front propagating principally in the horizontal direction from the injector, providing important reservoir boundary pressure support and minimizing the chance for injected water short-circuiting at the sandface. Ultimate Oil Recovery of 5spot/line drive patterns and the P-I strategy were similar, 54% and 52% respectively. Well completion costs and forecasts were fed into simple economics spreadsheet to test which technique provides the most value. Open book economics results showed the P-I concept provides better value (NPV 23.0 and VIR 0.67) than 5 spot and line drive patterns (NPV-17 and VIR-0.14).

scholarly journals Numerical evaluation of the performance of a single-well groundwater source heat pump system in Beijing, China

2019 ◽  
Vol 38 (1) ◽  
pp. 201-221 ◽  
Author(s):  
Tianfu Xu ◽  
Fengyu Li ◽  
Bo Feng ◽  
Guanhong Feng ◽  
Zhenjiao Jiang
Keyword(s):  
Heat Transport ◽  
Heat Pump ◽  
Transport Model ◽  
Heat Pumps ◽  
Transport Processes ◽  
Pump System ◽  
Heat Pump System ◽  
Single Well ◽  
Groundwater Source ◽  
Beijing China

Shallow geothermal energy is stable and clean. Using a heat pump to produce groundwater and realize heating and cooling can effectively prevent haze and reduce energy consumption. To reduce engineering costs, many buildings in Beijing, China, plan to utilize single-well groundwater source heat pumps. Numerical modeling is an effective way to gain an understanding of thermal transport processes. However, wellbore-reservoir coupling and the uncertainty of productivity due to geological parameters make simulation difficult. A wellbore-reservoir-integrated fluid and heat transport model is defined by T2Well simulator to predict the productivity of a typical single-well system, with consideration of complex geological factors. The model is validated by the analytical model developed in Beijing, China. The fluid processes in the wellbore are described by 1 D non-Darcy flow, and the reservoir 3 D fluid and heat transport processes are calculated. Six crucial factors satisfying a random distribution are used, and for a single well that can supply heat for an area of 9000 m2, the output temperature during the heating season ranges from 11°C to 15°C.

Regional parametric sensitivity analysis of Walloon Subgroup CSG production

2017 ◽  
Vol 57 (1) ◽  
pp. 277
Author(s):  
Daren Shields ◽  
Fengde Zhou ◽  
Joan Esterle
Keyword(s):  
Gas Production ◽  
Gas Content ◽  
Project Schedule ◽  
Coal Seam Gas ◽  
Simulation Experiments ◽  
Reservoir Performance ◽  
Well Completion ◽  
Reservoir Models ◽  
Single Well ◽  
Eastern Edge

Following two decades of intensive exploration, coal seam gas (CSG) production in the Surat Basin has begun to dramatically increase to meet the capacity of three newly completed CSG to liquefied natural gas (LNG) export projects. As the industry’s focus shifts from appraisal to exploitation, the production forecasts underpinning these LNG projects are being tested. In some cases predicted reservoir performance is found to be invalidated by observed production data, a condition that may require costly amendments to project schedule and scope. The deviation between actual and predicted reservoir performance can often be attributed to an incomplete understanding of parametric uncertainties present in static or dynamic reservoir models. To address this limitation, this study aims to explore the parametric controls upon CSG production behaviours with a series of simulation experiments. Distributions of reservoir parameters were compiled from 152 open-source well completion reports available in three areas along the eastern edge of the Surat Basin. These distributions were validated and then sampled to extract representative ranges for subsurface factors including gas content, permeability, net coal thickness, Langmuir pressure, Langmuir volume and drainage area. These inputs were used to construct single well radial models, which were then simulated to generate predictions of monthly and cumulative produced fluid volumes. The results of this study indicate that net coal thickness and lateral coal connectivity are the most sensitive factors with respect to cumulative gas production, while permeability was the single most influential parameter affecting the rate of gas production.

Dewatering Preloading Test and Ground Subsidence in a Project

2011 ◽  
Vol 250-253 ◽  
pp. 1912-1916
Author(s):  
Yong Mou Zhang ◽  
Jian Chang Zhao
Keyword(s):  
Water Level ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
New Technology ◽  
Soft Soil ◽  
Soil Treatment ◽  
Ground Subsidence ◽  
Confined Water ◽  
Phreatic Water ◽  
The Relationship

Ground subsidence is one of the main geological hazards in Shanghai. The ground subsidence is caused by pumping groundwater greatly. In the past, studies of ground subsidence in Shanghai were mostly taken for the ground subsidence caused by pumping confined water in Puxi. And ground subsidence caused by pumping phreatic water was rarely studied. Dewatering preloading is a new technology for soft soil treatment. The monitoring of ground water level, ground subsidence, pore water pressure in the process of dewatering preloading test for a soft soil treatment project in Pudong showed that pumping phreatic water can also cause ground subsidence. The ground subsidence caused by pumping phreatic water was analyzed in this paper. The relationship between phreatic water level and ground subsidence was obtained.

scholarly journals Distribution of fluoride in groundwater around Chagan Lake and its risk assessment under the influence of human activities

2020 ◽  
Vol 20 (7) ◽  
pp. 2441-2454
Author(s):  
Peng Xu ◽  
Jianmin Bian ◽  
Juanjuan Wu ◽  
Yihan Li ◽  
Fei Ding
Keyword(s):  
Risk Assessment ◽  
Fluorine Content ◽  
Reference Value ◽  
Fluoride Content ◽  
Assessment Model ◽  
Risk Assessment Model ◽  
Confined Water ◽  
Model Based ◽  
Phreatic Water ◽  
Chagan Lake

Abstract Chagan Lake is located in the area of Western Jilin for which waterways have high fluorine content. Because of the construction of water conservancy projects and agricultural irrigation areas, the groundwater replenishment and drainage conditions there have changed. Groundwater test data were used to analyze the status of groundwater fluoride with this changing hydrodynamic gradient. The paper established a health risk assessment model based on triangular fuzzy number. The results show that the samples of phreatic water and confined water with excessive fluoride content accounted for 68.74% and 29.4%, respectively. Samples that exceeded standards of fluoride content were mainly distributed in the northwest and southwest. The chemistry of phreatic water is more complicated than that of confined water. The water quality categories are mainly poor and very poor. The formation of major anions and cations was mainly controlled by evaporation and rock weathering. It was also found that non-carcinogenic risks of fluoride in phreatic water are greater than those in confined water. The risk indices for children and adults were [1.1, 1.6] and [0.6, 0.9], respectively (α = 0.8). The non-carcinogenic risk assessment model based on triangular fuzzy numbers has a higher reference value than that of traditional models.

Identification of Well Completion and Hydraulic Fracturing Performance Factors of Initial Development Wells within a Tight Oil Project in West China

2015 ◽  
Author(s):  
Jing Zhang ◽  
Xu Jiangwen ◽  
Hong Jiang ◽  
Tobias Judd ◽  
Yuan Liu ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Reservoir Characterization ◽  
Junggar Basin ◽  
Microseismic Monitoring ◽  
Western China ◽  
Rapid Decline ◽  
Initial Development ◽  
Chemical Tracers ◽  
Well Completion ◽  
Single Well

Abstract The early development of a systematic approach to well completion practices centralized around multistage hydraulic fracturing treatments is often the critical component to sustainable reservoir exploitation and development. Unfortunately, the exploitation of either exploratory or underdeveloped resources often has a number of issues that include the understanding of geological heterogeneity with different results observed within close proximity and the need to optimize completion techniques to offset the potential rapid decline in well productivity. For these cases, well completion and stimulation practices are of utmost importance with the optimization and evaluation of such designs to include and account for the integration of all reservoir and geomechanical parameters. Recent vertical well results from initial exploratory wells combined with single-well horizontal pilot wells has accelerated the development plans for the Jimusaer field located in the Junggar basin of western China. This field covers a surface area of 300,000 acres with the targeted reservoir being located between 2,300 to 4,255 m true vertical depth (TVD). The application of horizontal wells from multiwell pads with each well consisting of up to 23 hydraulic fracturing treatments was meant to exploit large volumes of hydrocarbon reserves that were previously thought unattainable. Operationally, the first four wells consisted of 62 hydraulic fracturing stages and were executed within a 28-day period. The project included the application of an integrated workflow including reservoir characterization along the length of the horizontal well lateral, deployment of novel multistage openhole completion techniques with dissolvable isolation technology, factory fracturing approach with all stages being monitored by microseismic monitoring, and application of chemical tracers on selected stages to identify zonal contribution during flowback and cleanup operations. This paper describes how the acquisition of crucial reservoir and fracturing data combined with operational performance can identify areas for improvement of future completions while strengthening existing ones.

Analysis and assessment of confined and phreatic water quality using a rough set theory method in Jilin City, China

2015 ◽  
Vol 15 (4) ◽  
pp. 773-783 ◽  
Author(s):  
He Huang ◽  
Xiujuan Liang ◽  
Changlai Xiao ◽  
Zhong Wang
Keyword(s):  
Water Quality ◽  
Groundwater Quality ◽  
Pore Water ◽  
Set Theory ◽  
Rough Set ◽  
Rough Set Theory ◽  
Quality Data ◽  
Confined Water ◽  
Permissible Limits ◽  
Phreatic Water

In groundwater quality assessments it is easier and more effective to reduce the number of parameters included in water quality indices. A total of 20 quaternary loose rock pore water and tertiary clastic rock cranny pore water data sets were used for Jilin City, China, as basic data, and 10 water quality parameters were selected for reduction using rough set theory and a statistical analysis of groundwater quality. Results showed that the quality of confined water was better than that of phreatic water in the study area. Confined water was of good quality, and met the permissible limits of the Quality Standards for Groundwater of China, with the exception of NH4+ and F−. For phreatic water, the five parameters of total dissolved solids, NH4+, NO2−, Fe, and F− exceeded the permissible limits, with levels of NH4+ and Fe having a 70% and 40% rate of exceedance, respectively. The results indicated that water evaluation before and after attribute reduction was consistent, which suggests that through rough set theory redundant parameters in indices were eliminated but the accuracy of water quality classification remained effective, while the complexity of the calculation was reduced. Rough set theory provides a convenient and appropriate way to manage large amounts of water quality data.

scholarly journals INTELLIGENT NATURAL DUMP FLOODING WELL - CASE STUDY FROM THE AREA OF THE WESTERN PERSIAN/ARABIAN GULF AND POSSIBLE APPLICATION IN THE CROATIAN MATURE OIL FIELD BENIČANCI

2020 ◽  
Vol 35 (4) ◽  
pp. 21-31
Author(s):  
Damir Zadravec ◽  
Vladislav Brkić
Keyword(s):  
Natural Water ◽  
Water Injection ◽  
Arabian Gulf ◽  
Pilot Project ◽  
Oil Field ◽  
Oil Reservoir ◽  
Reservoir Pressure ◽  
Well Completion ◽  
Execution Phase ◽  
Single Well

In the process of oil reservoir waterflooding, natural water dump flood technology for reservoir pressure decline prevention is considered as an unconventional but technically less demanding, more economical and safer method in comparison to surface power water injection. With natural dump flood technology, a single well serves as a water producer from a water bearing layer (aquifer) and simultaneously through gravity and the pressure difference between the aquifer and the depleted oil reservoir, it serves as a water injector inside the oil reservoir without expensive and complex injecting water treatment facilities at the surface. With the use of such technology and the running of intelligent well completion, it allows for the permanent monitoring of water production, injection rates and temperature inside the chosen reservoir. In addition, in offshore operations, the use of a subsea wellhead with a mud line suspension system allows for the placing of the injector well at the best predetermined position for water injection in a targeting reservoir and, together with an efficient subsurface acoustic data acquisition system, leads to better reservoir management and well integrity improvement. The overview and critical reflection of the drilling and intelligent completion of a natural dump flooding well for reservoir pressure support in partially depleted oil reservoirs in the Persian/Arabian Gulf has been given, referring to both their preparation and execution phase. The possibility of applying natural water dump flood was also considered in the Croatian onshore Beničanci oil field through a pilot project of water injection into the Be-62 well.

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