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Natural rubber latex as a potential additive for water-based drilling fluids

Petroleum Science 2024年第4期21卷 2677-2687页

作者： Jun Yang guan-cheng Jiang Jing-Tian Yi Yin-Bo He li-li Yang Teng-Fei Dong Guo-Shuai wang college of Petroleum engineering China University of Petroleum (Beijing) National engineering Research Center of Oil & Gas Drilling and Completion Technology Changqing Drilling General Company CNPC Chuanqing Drilling Engineering Company Limited

The environmental hazards and "carbon footprint" of oil and gas drilling can be significantly reduced by replacing traditional petroleum-based chemical additives with natural materials derived from plants and animals. This paper explored for the first time the interaction mechanism between natural rubber latex(NRL) and bentonite suspensions(BTs) through a series of characterization experiments, as well as the potential applications in water-based drilling fluids(WBDF). The gel viscoelasticity experiments showed that NRL could decrease the consistency coefficient(k) and flow index(n) of BTs, and enhance the shear thinning performance of BTs as pseudo-plastic fluids. In addition, 0.5 w/v% NRL not only increased the critical yield stress and strengthened the structural strength between the bentonite particles, but also facilitated the compatibility of pressure loss and flow efficiency. The evaluation of colloidal stability and WBDF performance indicated that NRL particles could promote the hydration and charge stability on the surface of BTs particles, and optimize the particle size distribution and flow resistance of WBDF under the "intercalation-exfoliation-encapsulation" synergistic interaction. Moreover, NRL can improve the rheological properties of WBDF at high temperatures(dense blocking layer by bridging and sealing the pores and cracks of the filter cake, which ultimately reduces the permeability of the cake and the filtration loss of WBDF.

关键词： Natural materials water-based drilling fluids Natural rubber latex Bentonite suspensions Filtration loss

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NUMERICAL MOdeliNG OF COMPOUND CHANNEL FLOWS

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Journal of Hydrodynamics 2002年第4期14卷 106-109页

作者： wang de-guan, cheng li college of water resources and environmental engineering, hohai University,{3., china college of water resources and {3. engineering Hohai University Nanjing 210098 China

A numerical model capable of predicting flow characteristics in a compound channel was established with the 3.D steady continuity and momentum equations along with the transport equations for turbulence kinetic energy and dissipation rate. Closure was achieved with the aid of algebraic relations for turbulent shear stresses. The above equations were discretized with implicit difference approach and solved with a step method along the flow direction. The computational results showing the lateral distribution of vertical average velocities and the latio of total flow in the compound channel agree well with the available experimental data.

关键词： compound channel flow discharge ratio of channel and floodplain turbulence

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NUMERICAL STUDY ON THE PURIFICATION PERFORMANCE OF RIVERBANK

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Journal of Hydrodynamics 2007年第5期19卷 643-652页

作者： DAI Yu wang de-guan college of environmental Science and engineering Hohai University Nanjing 210098 China

During the rain time, the runoff infiltrates into the riverbank through the collecting gutter and slope surface. The city runoff is generally polluted by organic, oil, heavy metal particulates, etc. The pollutants moving with the water through the riverbank experience advection, dispersion, diffusion, adsorption, biochemical reaction and plant uptaking processes. In this article, a mathematical model was developed to simulate the performance of pollutant removal of the riverbank. The model took those main mechanisms into account. The modified Richards equation was used in simulating flow field. The mass balance law was employed in deriving the equation for pollutant transport, where the diffusion and dispersion were described with the Fick-type law, the adsorption was macroscopically expressed as form isotherm, and the bio-chemical degradation process was assumed to follow the Monod kinetics. The NH3.N and TP were considered in the present model. The mathematical model was descritized with a finite element numerical model, which was applied to two types of model riverbanks. In the model test, the hydraulic loading was assumed to have the intermittent pattern simulating the storm runoff of certain return period, and the values of the rainfall runoff and concentrations of the NH3.N and TP were taken from the model test. The computed overall removal rates for the NH3.N and TP in 6 cases are in the range of 88%-98%, 87%-97%, respectively. The differences between the computed and tested overall removal rates for the NH3.N and TP are less than 5%. The time-varying oscillation pattern of the concentrations of the NH3.N and TP were rationally simulated, which shows that the model presented in this article can be used to assess the purification performance of the riverbank constructed with sand or soil.

关键词： riverbank numerical modelling purification,pollutant experiments

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INFLUENCE OF SEEPAGE FACE OBliQUITY ON DISCHARGE OF GROUNDwater AND ITS POLLUTANT INTO LAKE FROM A TYPICAL UNCONFINED AQUIFER

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Journal of Hydrodynamics 2007年第6期19卷 756-761页

作者： li Yong wang Chao YANG lin-zhang li Yi-ping State Key Laboratory of Hydrology-water resources and Hydraulic {3. Hohai University Nanjing 210098 China college of environmental Science and engineering Hohai University Nanjing 210098 China Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 China

Lab experiment and mathematical simulation Modular three dimensional finite difference groundwater （MODFLOW） were performed in a soil tank to simulate the hydrogeochemical interaction between lake and typical unconfined aquifer. Results show that the velocity decreases exponentially with the transect distance on seepage face. The maximal velocity occurs at the top point of seepage face. The obliquity of seepage face has a great influence on the maximum and distribution of seepage velocity. With the increase of the obliquity of seepage face, the maximal velocity decreases quickly and the velocity distribution becomes much more even. Most of groundwater flow and pollutant flux discharges through a narrow portion near the top of seepage face. The flow and mass concentrated in the narrow portion increase with the decrease of the obliquity of seepage face. These will benefit to design a reasonable and economical scenario to manage lakeshore and to control the pollution of lake water near lakeshore.

关键词： shallow lake unconfined aquifer groundwater discharge velocity distribution chloride MODFLOW

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Back analysis of mechanical parameters of roller compacted concrete dam

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Science china(Technological Sciences) 2010年第3期53卷 848-853页

作者： GU ChongShi 1,2,3.li Bo 1,XU guangLei 4 &YU Hong 1,2,3.1 State Key Laboratory of Hydrology-water {3. and Hydraulic engineering,hohai University,nanjing 210098,china 2college of water Conservancy Hydropower,hohai University,nanjing 210098,china 3.ational engineering Research Center of water {3. engineering Safety,Efficient Utilization and nanjing 210098,china 4 nanjing Hydraulic Research Institute,nanjing 210029,china 1. State Key Laboratory of Hydrology-water resources and Hydraulic {3. Hohai University Nanjing 210098 China2. College of Water Conservancy Hydropower Hohai University Nanjing 210098 China3. National Engineering Research Center of Water Resources Engineering Safety Efficient Utilization and Nanjing Nanjing 210098 China4. Nanjing Hydraulic Research Institute Nanjing 210029 China

In view of the diversity and complexity of mechanical parameters of roller compacted concrete dam(RCCD),the uniform design method,partial least-squares regression(PLS)and least squares support vector machine(LSSVM)were applied to the back analysis of RCCD with the use of the complex nonlinear relationship between dam mechanical parameters and dam *** the process of back analysis,the initial samples of parameters were designed with uniform design ***,a transversely isotropic model of RCCD was established by *** *** this model,training samples of LSSVM model could be *** then,the complex nonlinear relationship between relative values of hydraulic components of dam displacements and mechanical parameters was ***,actual relative values of dam hydraulic components are isolated from the measured data of dam displacements by using *** inputting the isolated relative values into LSSVM model,the back analysis values of RCCD mechanical parameters can be *** example analysis showed that mechanical parameters obtained by the above-mentioned back analysis method are reasonable,and the back analysis method is feasible.

关键词： roller compacted concrete dam mechanical parameters back analysis

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THEORETICAL ESTIMATION OF GROUNDwater DISCHARGE AND ASSOCIATED NUTRIENT LOADING TO A LAKE WITH GENTLE SLOPE BOTTOM

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Journal of Hydrodynamics 2007年第1期19卷 30-35页

作者： li Yong wang Chao college of environmental Science and engineering Hohai University Nanjing 210098 China

A simple estimation model of groundwater discharge and nutrient flux from nearshore unconfined aquifer to lake was studied. It was supposed that the aquifer was permeable isotropic homogeneously and its thickness approximated to the depth of lake. Distribution of the hydrau{3.c gradient and the specific discharge along the transect of the discharge zone were discussed. Results show that the groundwater discharge patterns vary with the inc{3.nation angle of lakeshore bottom. For a shallow lake with gentle slope bottom, the rate of discharge of groundwater to lake is not constant across a discharge zone, but the discharge is concentrated in a narrow portion of the {3.ttoral zone where the Dupuit assumptions are inva{3.d. The width of the discharge zone is correlative with aquifer thickness and slope of the lake bottom. The distribution functions of hydrau{3.c gradient and groundwater discharge rates accord exponentially with offshore distance.

关键词： shallow lake unconfined aquifer groundwaterdischarge nutrient loading

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Study on the simulation of transparency of Lake Taihu under different hydrodynamic conditions

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Science china Earth Sciences 2006年第z1期49卷 162-175页

作者： PANG Yong, li Yiping & LUO liancong college of {3. Science and engineering, hohai University, nanjing 210098, china nanjing Institute of Geography & limnology, Chinese Academy of Sciences, nanjing 210098, china hohai Univ Coll Environm Sci & Engn Nanjing 210098 Peoples R China Chinese Acad Sci Nanjing Inst Geog & Limnol Nanjing 210098 Peoples R China

It was indicated in this study that there were negative relations between the concentrations of suspended solid (SS) and transparency according to the analysis of measured data of Lake Taihu. Their relations in pervious studies were reviewed, which showed that the changes of transparency in Lake Taihu could be reflected by simulating suspended solid concentration (SSC). Measured data showed that the changes of SSC with wind speed were similar at different water *** increased with the increasing of wind speed. Both wave and lake current of Lake Taihu had positive relations with SSC. However, wave was the main factor affecting sediment suspension, while flow took the second place. In this study, a numerical model coupling lake current, wave and SSC of Lake Taihu was developed. In the SS model, the combined effects of wave and current were *** amounts of suspended and deposited sediments near the lake bed surface layer were treated separately. The stochastic characteristics of turbulent flow pulsation near lake beds were also considered, and the start-up conditions of sediment suspension were introduced to the model. The model elucidated the mutual exchange processes between sediment particles in SS and active sediments within and on the bed surface layer. Simulated results showed that lake current had relatively significant effects on the SSC at littoral areas of Lake Taihu, while SSC at the central area of the lake was mainly influenced by wave. The changes of transparency with SSC were simulated for Lake Taihu using this model. Calculated results were validated by measured data with good fitness, which indicated that the model is basically suitable for the simulation and prediction of transparency of Lake Taihu.

关键词： transparency suspended solid hydrodynamlc sediment suspension model.

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A STUDY ON NUMERICAL METHOD OF NAVIER-STOKES EQUATION AND NON-liNEAR EVOLUTION OF THE COHERENT STRUCTURES IN A LAMINAR BOUNDARY LAYER

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Journal of Hydrodynamics 2006年第3期18卷 372-377页

作者： LU Chang-gen CAO Wei-dong QIAN Jian-hua State KeyLaboratory of Hydrology-water resources and Hydraulic {3. and college of environmental Science and {3. Hohai University Nanjing 210098 China college of environmental Science and engineering Hohai University Nanjing 210098 China

A new method for direct numerical simulation of incompressible Navier-Stokes equations is studied in the paper. The compact finite difference and the non-linear terms upwind compact finite difference schemes on non-uniform meshes in x and y directions are developed respectively. With the Fourier spectral expansion in the spanwise direction, three-dimensional N-S equation are converted to a system of two-dimensional explicit-implicit The treatment of equations. The third-order mixed scheme is employed the three-dimensional for time integration. non-reflecting outflow boundary conditions is presented, which is important for the numerical simulations of the problem of transition in boundary layers, jets, and mixing layer. The numerical results indicate that high accuracy, stabilization and efficiency are achieved by the proposed numerical method. In addition, a theory model for the coherent structure in a laminar boundary layer is also proposed, based on which the numerical method is implemented to the non-linear evolution of coherent structure. It is found that the numerical results of the distribution of Reynolds stress, the formation of high shear layer, and the event of ejection and sweeping, match well with the observed characteristics of the coherent structures in a turbulence boundary layer.

关键词： non-uniform meshes compact finite differences scheme Fourier spectral expansion coherent structure boundary layer

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Review on hidden trouble detection and health diagnosis of hydraulic concrete structures

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Science china(Technological Sciences) 2007年第z1期50卷 34-50页

作者： WU ZhongRu1,2?, li Ji1, GU ChongShi1,2 & SU HuaiZhi1,2 1 college of water Conservancy and Hydropower {3., hohai University, nanjing 210098, china 2 National {3. Research Center of water resources Efficient Utilization and {3. Safety, nanjing 210098, china college of water Conservancy and Hydropower engineering Hohai University Nanjing 210098 China National engineering Research Center of water resources Efficient Uti{3.zation and engineering Safety Nanjing 210098 China

A large number of hydraulic concrete structures have hidden defects such as cracks, erosion, freeze and thaw, thermal fatigue, carbonization. These hidden defects seriously affect the strength, stability and durability of structures. These problems are studied mainly by single monitoring or diagnosis methods at present. The integration of multiple monitoring and diagnosis methods is not applied widely. Besides, the analysis theory on these problems is not developed very well. The systemic study on the aging mechanism of hydraulic concrete structures, time- variation model and health diagnosis is still not enough. The support for {13. practice is limited. Aimed at these major scientific and technological problems and combined with specific projects, study on detection of hidden defects and health diagnosis of hydraulic concrete structure has been carried out. This study includes the following content: field non-destructive examination of hidden defects of hydraulic concrete structures, seepage detection, the construction of in-situ sensing system, the combination of field detection and in-situ monitoring, the mechanism of crack, freeze and thaw, erosion and carbonization of hydraulic concrete structure, mechanism of combination aging; time-variation model of hydraulic concrete structure, theories and methods for health diagnosis of hydraulic concrete structures.

关键词： hydraulic concrete structure hidden trouble detection health diagnosis

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Field experiments on greenhouse gas emissions and nitrogen and phosphorus losses from rice paddy with efficient irrigation and drainage management

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Science china(Technological Sciences) 2011年第6期54卷 1581-1587页

作者： PENG ShiZhang1,2,YANG ShiHong1,2,XU JunZeng1,2 & GAO HuanZhi1,2 1State Key Laboratory of Hydrology-water resources and Hydraulic {3.,hohai University,nanjing 210098,china 2college of water Conservancy and Hydropower {3.,hohai University,nanjing 210098,china 1. State Key Laboratory of Hydrology-water resources and Hydraulic {3. Hohai University Nanjing 210098 China2. College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China

Greenhouse gas emissions,nitrogen and phosphorous losses through ammonia volatilization,leaching and surface drainage from rice paddy under efficient irrigation and drainage were analyzed based on field experimental data in order to reveal the eco-{3. impacts of efficient irrigation and drainage on rice *** results showed that total methane emission from rice paddy under the controlled irrigation was reduced by more than 80% and total nitrous oxide emission increased by 15.9% compared with flooding *** comprehensive global warming potentials(GWP) of methane and nitrous oxide were 62.23.gCO2 m-2 for rice paddy under the controlled irrigation,reduced by 68.0% compared with flooding *** to large reduction in seepage and surface drainages,nitrogen and phosphorous losses through leaching were reduced by 40.1% and 54.8%,nitrogen and phosphorous losses through surface drainage were reduced by 53.9% and 51.6% from rice paddy under efficient irrigation and drainage compared with traditional irrigation and *** loss through ammonia volatilization was reduced by 14.0%.Efficient irrigation and drainage management is helpful to mitigate greenhouse gases emission,nitrogen and phosphorus losses and their pollution on groundwater and surface water.

关键词： efficient irrigation and drainage nitrogen and phosphorus greenhouse gas ammonia volatilization paddy field

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