A new evaluation method of gel’s dynamic sealing characteristic in porous media

Water shutoff through injection wells is one of the most important techniques used for water injection profile control and modification in severely heterogeneous reservoirs, aiming at stabilizing oil production. It has been widely reported that the effectiveness and efficiency of water shutoffusing gel is mostly dependent on the gel dynamic sealing properties in the porous media. Firstly the gelation strength and gelation time of polymer gel were evaluated. Then, core flowing experiments were conducted before and after gelation in a 32 m long sand pack. In addition, water flooding core experiments were also carried out in a long core of 80 cm before and after injecting gel system to check the reliability of this evaluation method. The experimental results show that moderate-strength gel can be formed at 65 ~C. According to the integrated evaluation of the plugging coefficient, plugging strength and water breakthrough time, the gel particles are capable of migrating to a distance of 7.47 m from the injection point of the 32 m long sand pack during the water injection process after gelation. Based on sands gelation status and effluent analyses, the effective migration distance of the gel particles is 4-14 m. Through the core flooding experiments using the 80 cm heterogeneous core, it is evidenced that the gel can be formed in the deep reservoir （40.63% of total length） with the plugging strength as high as 6.33 MPa/m, which leads to extra oil recovery of 10.55% of original oil in place （OOIP） by water flooding after gel treatment.     

Synthesis and characterization of multi-walled carbon nanotube doped silica aerogels

Multi-walled carbon nanotube doped silica aerogels(MWCNT-SAs) were synthesized from a wet gel of well-dispersed MWCNT by one-step solvent exchange/surface modification and ambient pressure drying(APD). Waterglass was employed as a precursor to prepare wet gel. The content of MWCNT varied from 0 to 15% volume by wet gel. The surface group, thermal stability and microstructure of pure silica aerogel and MWCNT-SAs were investigated by FTIR, DTA, and TEM. Experimental results show that MWCNT-SAs are hydrophobic when the temperature is below 400 ℃, MWCNT-SAs exhibit a mesoporous network structure, and they achieve the largest scale with least shrinkage and lowest density when doped with 5 vol% MWCNT.     

Determination of the solvation film thickness of dispersed particles with the method of Einstein viscosity equation

The dispersion of a solid particle in a liquid may lead to the formation of solvation film on the particle surface, which can strongly increase the repulsive force between particles and thus strongly affect the stability of dispersions. The solvation film thickness, which varies with the variation of the property of suspension particles and solutions, is one of the most important parameters of the solvation film, and is also one of the most difficult parameters that can be measured accurately. In this paper, a method, based on the Einstein viscosity equation of dispersions, for determining the solvation film thickness of particles is developed. This method was tested on two kinds of silica spherical powders （namely M1 and M2） dispersed in ethyl alcohol, in water, and in a water-ethyl alcohol mixture （1：1 by volume） through measuring the relative viscosity of dispersions of the particles as a function of the volume fraction of the dry particles in the dispersion, and of the specific surface area and the density of the particles. The calculated solvation film thicknesses on M1 are 7.48, 18.65 and 23.74 nm in alcohol, water and the water-ethyl alcohol mixture, 12.41, 12.71 and 13.13 nm on M2 in alcohol, water and the water-ethyl alcohol mixture, respectively.     

Nano-silica particles enhanced adsorption and recognition of lysozyme on imprinted polymers gels

Molecular imprinting technology has a great potential to be used in protein separation and purification.In this work,lysozyme imprinted polyacrylamide gel was prepared with silica particles as a sacrificial template to generate macro-porosity for fast adsorption.The adsorption equilibrium time and adsorption capacity were 9 h and 56 mg/g respectively,which was 2 h less and 2.3-fold more than polymers without the sacrificial template.In order to test molecular imprinting polymers(MIPs)'selectivity,bovine serum albumin(BSA)was chosen as interferent for binary adsorption tests.In addition,the adsorption selectivity was further investigated using different molar ratios of lysozyme to BSA with fixed total concentration of proteins,as well as using various total concentrations of proteins with an equimolar ratio of lysozyme to BSA.It has been proven that the total concentration of proteins should be larger than1.5×10~(-7) mol/mL,when the molar ratio of BSA to Lyz is 1∶1,in order to effectively separate Lyz from the binary protein mixture.The macro-porous lysozyme molecularly imprinted polymers have less adsorption time,larger adsorption capacity,and better imprinting effect.     

Lead removal from aqueous solution by employing natural brucite

The effect and mechanism of the removal of Pb^2 from an aqueous solution by using brucite as the adsorbent were studied. It was revealed that the increase in pH of brucite suspension, as a result of the release of magnesium hydroxide into the suspension, leads to a sharp rise of the adsorption amount of Pb^2 on brucite. The synergism of buffering and adsorption capacities of brucite is responsible for the removal of Pb^2 from the aqueous solution. The coexistence of Cu^2 with Pb^2 causes a decrease of their adsorption on brucite due to a competition for surface sites and brucite exhibits a higher adsorption capacity for Pb^2 than for Cu^2 . The percentage adsorption of Pb^2 on brucite could reach 96.38%, 97.20% and 94.09% respectively with the initial pH of the suspension pHi= 1,76 (initial Pb^2 concentration [Pb^2 ]i = 20μmol/L), 1.82 ([Pb^2 ]i=100μmol/L ) and 1.84 ([Pb^2 ]i = 500 μmol/L). It was concluded that brucite is a very efficient mineral adsorbent for Pb^2 removal from polluted acidic water.     

Low-cost preparation of mesoporous silica with high pore volume

Mesoporous silica materials with high pore volume were successfully prepared by the chemical precipitation method, with water glass and a biodegradable nonionic surfactant polyethylene glycol （PEG）. The obtained materials were characterized by transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, thermo gravimetric analyzer and differential scanning calorimetry （TG-DSC）, nitrogen adsorption-desorption measurements, and X-ray diffraction （XRD）. The results showed that the changes of the pore parameters depended on both the surfactant content and heat treatment temperature. When the content of PEG was 10wt% and the obtained PEG/SiO2 composite was heated at 600℃, the mesoporous silica with a pore volume of 2.2 cma/g, a BET specific surface area of 361.55 m^2/g, and a diameter of 2-4 μm could be obtained. The obtained mesoporous silica materials have potential applications in the fields of paint and plastic, as thickening, reinforcing, and flatting agents.     

Silicon isotope study of thermal springs in Jiaodong Region,Shandong Province

Based on δ30Si and δ32Si isotope geochemistry, the origin and evolutionary mechanism of thermal springs in Jiaodong region are studied. The mean value of δ30Si of dissolved silica of thermal spring water in Jiaodong is 0.1‰. Thermal spring water ages using δ32Si dating method range from 387a to 965a.     

Evaluation of the exploitation of nontraditional water resources—— Case study of Yantian District in Shenzhen

Yantian District in Shenzhen is a water deficient area. Water shortage has become a major obstacle to its further economic progress. Consequently, rational exploitation of nontraditional water resources(NWR)has been naturally adopted to increase local available water volume. The purpose of this paper is to analyse the exploitation of two kinds of NWR, namely wastewater reuse and seawater utilization, in Yantian District, and assess the contribution of each mode to deal with the water crisis. Two different nontraditional water supply systems respectively based on the reclaimed water and sea water were presented, and the effects of each system were evaluated in terms of technology, economy and environment. The result shows that both wastewater reclamation and reuse (WRR) and direct utilization of seawater (DUS) are of great importance to cope with the tight water resource situation in the district. The data indicate that the fresh water saved by WRR system and DUS system is 29 and 17 million m3/a respectively. Moreover, the BOD, COD, NH3-N and T-P reduced by the WRR system are 870, 2900, 725 and 87 t/a, respectively. Considering the integrated effectiveness, the development of WRR system, which is of specific significance to exploiting new water resource and save natural fresh water supplied from distant water diversion project, is the preferred methods used to solve the water shortage problem in Yantian District and recover the water environment as well as maintain the sustainable development of the city zone.     

Investigation on adsorption and regeneration performances of multi-walled carbon nanotubes by supercritical water technique

In this paper,adsorption and regeneration characteristics of multi-walled carbon nanotubes (MWNTs) used as adsorbent were investigated for the removal of 1,3-benzenediol (BDO) from water by the supercritical water (SCW) technique. FTIR,XPS,SEM and dispersion stability tests were used to characterize the structure and surface morphology of CNTs. The results showed that CNTs surfaces were slightly activated and strongly etched in supercritical water system. The adsorption capacity of SCW-treated CNTs was higher than that of raw CNTs. The adsorbed amounts for treated CNTs and raw CNTs samples at the same initial concentration of 60 mg/L were ca. 16.42 and 7.30 mg/g,respectively. The BDO adsorption of treated CNTs was due to the physical adsorption. The experimental data fit Freundlich isotherm model better than Langmuir one. The loaded adsorbent could be efficiently desorbed and regenerated by SCW technique. Therefore,SCW is a promising and environmentally friendly technique for the improvement of adsorption and regeneration of CNTs.     

The Setting Chemistry of Glass Ionomer Cement

The setting chemistry of glass ionomer cement was imestigated by using mechanical determination of compressive strength at predetermined intervals,and measurement of structure changes of correspondling fracture sample by means of IR spectra and differential scanning calorimetry（DSC）.Zinc polycarboxylate cement was used as a comparison sample.The compressive strength of glass ionomer cement（GIC） increases with aging.IR spectra and DSC of corresponding fracture sample show the structure changes of the matrix and interface layer comprising of silica gel during the predetermined intervals studied.however,no significant changes occur in the zinc polycarxyolate cement.Hence the structure changes of the matrix and/or interface layer are responsible for compressive strength increasing with aging.The structure changes include the crosslink density,the ratio of complex form to ionic form,the content ratio of Al-PAA to Ca-PAA,the forming and maturing process of the interface layer comprising of silica gel.     

Characteristics of Membrane Fouling in an Anaerobic-（Anoxic/Oxic）^n-MBR Process

The characteristics of membrane fouling and cleaning, in a hybrid MBR process, was investigated. Under the condition of sub-critical flux operation, a characteristic three-stage trans-membrane pressure （TMP） profile is observed as time passes. The initially extended period of slow pressure rise, followed by a somewhat faster rise, is then sup- planted by a sudden transition to rapid pressure rise. Membrane cleaning experiments and SEM examination make it apparent that the rapid TMP rise is mainly caused by the accumulation of a surface cake layer, which is a reversible fouling that can be removed by tap water washing. Fouling caused by a gel layer, which is an irreversible fouling, can be removed efficiently by chemical cleaning. NaC10 can oxidize the gel layer, which is formed mainly of macromo-lecular organic substances. The HC1 can remove inorganic particles formed by Ca^2＋, Mg^2＋ ions etc. The sequence of chemicals used in membrane cleaning has an influence on the cleaning result. The effect of the NaC1O＋HC1 cleaning procedure is superior to that of the HCI＋NaC1O one. Particle size distribution measurements （PSD） reveal that fine particles are inclined to deposit or attach on the membrane surface, or in the membrane pores, and caused rapid fouling.     

Physical modeling of a sidetrack horizontal well production to improve oil recovery

The scaling criteria of physical modeling of a horizontal well production are discussed. A scaled experimental model was designed and realized. The experiments of a sidetrack horizontal well production have been carried out in the system, and the production curve variation is analyzed. The oil recovery of a sidetrack horizontal well production is compared with that of a vertical well, and the effect of factors such as sidetrack drilling time, water driving rate and the length of horizontal section on oil recovery are discussed. The production of a horizontal well changed both the fluid flow direction and pressure distribution in the reservoir; as a result the remaining oil in the dead oil region is recovered, and the ultimate oil output is raised.     

Sediment yield computation of the sandy and gritty area based on the digital watershed model

The Yellow River is well known as a sediment-laden river, which is the main reason that it cannot be controlled as easily as other rivers. Many researchers, such as Qian Ning et al., have found that the sediment load of the Yellow River comes mainly from the sandy and gritty area of the Loess Plateau. Therefore, it is very important to simulate the sediment yield in this area. This paper proposes a method to compute the sediment production in the sandy and gritty area based on the digital watershed model. The suggested model is calibrated and validated in the Chabagou basin, which is a small catchment in the study area. Finally, the model simulates the sediment yield of the sandy and gritty area in 1967, 1978, 1983, 1994 and 1997, which represents a high water and high sediment year, a mean water and mean sediment year, a high water and low sediment year, a low water and high sediment year, and a low water and low sediment year separately. The simulation results, including the runoff depth and erosion modulus, can well explain the "low water and high sediment" phenomena in the Yellow River basin. The total amount of the sediment production and its distribution generated by the model is very useful for water and soil conservation in the sandy and gritty area of the Loess Plateau.     

Physical and Chemical Properties of Sediments in Huainan Segment of Huaihe River

The chemical and physical properties of nitrogen and phosphorus as well as their concentrations in the overlying water, pore-water and sediments in Huainan segment of the Huaihe river were analyzed. The chemical forms of phosphorus in sediments were differentiated by a sequential fraction method. The results revealed that the NH4^ -N content in pore-water of 6 surface sediments is obviously higher than that in overlying water, indicating that there is a dynamic tendency of releasing NH4^ -N from sediment into overlying water. Chemical compound of nitrogen differs among segments of the river, while phosphorus has no such difference. Calcium bound phosphate (Ca-P) and iron bound phosphate (Fe-P) accounts for 60 % of the total phosphorus, and occluded-P (O-P) accounts for less than 20 %. Our findings indicate that 1) industrial waste water and domestic sewage have contributed to the excessive nutrient salts in Huaihe river, 2) decreased water flow during low water periods, and the interaction between sediments and overlying water disturbed by transport ships accelerate nutrient salt releasing into overlying water, which results in eutrophication of the river.     

Numerical Analysis of Effect of Water on Explosive Wave Propagation in Tunnels and Surrounding Rock

Based on the application of practical engineering, propagation processes of explosive waves in rock with water well and tunnel are simulated by ANSYS/LS-DYNA software. The evolution of damage in rock is presented. The effect of water on the damage of the concrete slab in a tunnel is compared with damage inflicted without water. The numerical simulation illustrates that water plays an important role in the evolution of damage of the concrete slab in a mine tunnel. In the presence of water in the rock the concrete slab is damaged more severely than without water in rock. The effect of water location in the rock is also considered. It is found that the concrete slab in the tunnel shows various degrees of damage as a function of the different locations of water. Attenuation laws of stress waves over time-space in rock with water are also obtained. Numerical results indicate that, under blast loading, there are three zones in the rock： a crushed zone nearby the explosive charge, a damaged zone and an elastic zone. The conclusions of numerical analysis may provide references for blasting designs and structure protection.     

Effect of solids on pulp and froth properties in flotation

Froth flotation is a widely used process of particle separation exploiting differences in surface properties. It is important to point out that overall flotation performance（grade and recovery） is a consequence of the quality and quantity of the solid particles collected from the pulp phase, transported into the froth phase, and surviving as bubble-particle aggregates into the overflow. This work will focus on studying these phenomena and will incorporate the effects of particle hydrophobicities in the 3-phase system. Solids are classed as either hydrophilic non-sulphide gangue（e.g. silica, talc）, hydrophilic sulphide（e.g. pyrite）, or hydrophobic sulphide（e.g. sphalerite）. Talc is a surface-active species of gangue that has been shown to behave differently from silica（frother adsorbs on the surface of talc particles）. Both are common components of ores and will be studied in detail. The focus of this work is to investigate the role of solids on pulp hydrodynamics, froth bubble coalescence intensity, water overflow rate with solids present, and in particular, the interactions between solids, frother and gas on the gas dispersion parameters. The results show that in the pulp zone there is no effect of solids on bubble size and gas holdup; in the froth zone, although hydrophilic particles solely do not effect on the water overflow rate, hydrophobic particles produce higher intensity of rates on water overflow and bubble coalescence, and many be attributed to the water reattachment.     

Chemieal Strueturcs and Adsorptive Behaviors of Superplastieizers on β-C2S

The chemical structures of four types of superplasticizers （SPs） and their adsorptive behaviors on β-C2S were investigated. The adsorption properties of SPs on β-C2S were measured and the relationship between the adsorption quantity and the specific surface of β-C2S was analyzed. The experimental results show that the adsorption quantity increases with the surface area increase of β-C2S, but the adsorption quantity per surface area is similar, which means that the main adsorbent is β-C2S itself. Polycarboxylic ester （PCE） showed the highest adsorption amount on β-C2S, followed by β-naphthalene sulfonates （NSF） and formaldehyde-acetone condensates sulfonates （FAS）, amino sulphonate （AS） showed the least adsorption amount on β-C2S. PCE affected the surface potential of β-C2S particles in water differently in comparison with other types of SPs. The adsorption capacity of SPs on β-C2S is determined by factors such as molecular structure, functional groups and molecular weight of SPs.     

STUDY ON THE HYDROLIZATION OF THE Na_2O-CaO-P_2O_5-SiO_2 BIOLOGICAL GLASSES

The bio-glass in the Na_2O-Ca_2O-P_2O_5-SiO_2 system involved in this paper is highly bio-active.The hydrolization of this glass with calcium phosphateand low silica is studied.The structure-compositicon-property relation of the glass is discussed by means ofIR spectrum,DTA and SEM.This study shows that:(a)the structure of the glass is mainly chain-like orlayer-like;(b)the glass is separated into a calciumphosphate-rich phase and a silica-rich phase;(c)thechain-or layer-like structure and the separation hareadvantages with hydrolization.     

Production and Properties of a Thickener with Ability of Suspending Sand

To overcome the shortcomings of pouring sands, a thickener with the ability to suspend sands was developed. It is mixed with sands to form densified slurry, and can insure the sands against deposition, jamming pipelines and dehydration. The chemical structure of the thickener is introduced in this paper and the production process is studied. The main processes include immersion, decomposition, dilution and addition of additives. In order to produce a thickener with high viscosity to suspend sands, key factors must be controlled in each process： the immersion time is 2 h; the mass fraction of formaldehyde is 0.01% and mass of NaCO3 accounts for 15% of dry material; the water temperature is 65 ℃ in summer and 72℃ in winter and the decomposition time is 2 h in the reaction; the densified decomposition solution should be diluted to 1% mass fraction; the additives of calcium ions and pH indicators must be added to the diluted liquid; the mass fraction of CaCl2 is 0.048% and the pH value of the solution is 7.5. The thickener is a gel with three-dimensional network structure, a liquid with non-Newtonian behaviour and the characteristics of pseudo-plastic material, a solution with little resistance and the ability to revive its oral primary viscosity. It has been successfully applied in Shendong Mines and has great value and wide-spread prospective use.     

Adsorption behavior of Pb^2＋ and Cd^2＋ ions on bauxite flotation tailings

The adsorption behavior of Pb^2＋ and Cd^2＋ ions on bauxite flotation tailings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings. The adsorption percentage of Pb^2＋ and Cd^2＋ ions as a function of adsorbent dosage, solution pH value and shaking time were determined by batch experiments. The maximum adsorption percentage of 99.93% for Pb^2＋ ions and 99.75% for Cd^2＋ ions were obtained by using bauxite flotation tailings as adsorbent. The methods, such as zeta potentials, specific surface area measurements and the analysis of adsorption kinetics, were introduced to analyze the adsorption mechanisms of the Pb^2＋ ions on bauxite flotation tailings. The isoelectric point of bauxite flotation tailings shifts from 3.6 to 5.6 in the presence of Pb^2＋ ions. The specific surface area of bauxite flotation tailings changes from 12.57 to 20.63 m^2/g after the adsorption of Pb^2＋ ions. These results indicate that a specific adsorption of the cation species happens on the surface of bauxite flotation tailings. Adsorption data of Pb^2＋ ions on the surface of bauxite flotation tailings can be well described by Langmuir model, and the pseudo-second-order kinetic model provides the best correlation for the adsorption data of Pb^2＋ and Cd^2＋ ions on bauxite flotation tailings.