聚合物驱在旅大油田的应用

渤海旅大油田为提高海上油田采收率,开展油田开发早期注聚的生产思路,扩大聚合物驱应用规模,决定在LD10-1油田A23井进行聚合物驱先导性试验。海上油田聚合物驱油从2003年在绥中36-1油田开始先导性试验,取得了良好的增油效果,适时推广到旅大油田。本文对聚合物驱在旅大油田现场工艺实施及配套应用进行了论述,并总结了实施过程中应注意的问题。     

Evaluation of modified cationic starch for impeding polymer channeling and in-depth profile control after polymer flooding

Premature polymer production in large quantities from flooding reservoirs is a serious problem commonly existing in some large oilfields in China. This is owing to polymer channeling through high permeability zones or pore passage. This paper presents a novel modified cationic starch, which can react with partially hydrolyzed polyacrylamide (HPAM) remaining in reservoir formation to form gels in-situ. The obtained gels can reduce polymer channeling and make successive injected water into mid-low permeability zones that achieve the purpose of deep profile control. The rheological property and the gel strength are examined. The singular sand-pack core-flood test results provide experimental evidence that the formed gel system is more effective in plugging high permeability pore passages. Moreover, the parallel core-flood test was conducted to simulate the process of in-depth profile modification in a heterogeneous formation. It has been found that this gel system can significantly enhance oil recovery and effectively reduce water-cut.     

The effect of polymer additives on the performance of a two-roll coater

The effect of polymer additives on the performance of a two-roll coater has been examined experimentally. The coater consists of a rigid steel roll and a deformable roll with polyurethane surface. Newtonian coating solutions and solutions with polymer additives were used as test fluids. Both forward and reverse coating operations were studied. It was found that for the forward coating operation, the shear-thinning behavior of the polymer solutions can reduce the coating thickness, but the fluid elasticity can increase the coating thickness significantly and can also destabilize the coating flow. For the reverse coating operation, a small amount of polymer additives can effectively increase the wipe ratio.     

乳液聚合瞬时乳胶粒大小和分布及其控制策略

乳液聚合中瞬时乳胶粒大小及分布与乳胶粒的形成和增长紧密相关,本文在苯乙烯,醋酸乙烯酯乳液聚合中考察了瞬时乳胶粒大小及分布。结果表明,在成核和稳定期乳胶粒增长速率较高,是控制乳胶粒大小及分布的关键阶段,由此提出了对于单体不同水溶性体系控制乳胶粒大小分布的策略,并以实验考核这些策略的合理性。     

Bound rubber theory and experiment

Adsorption of polymer on filler from bulk is known to result in a partial loss of polymer solubility (“bound rubber”). The existing theories of this phenomenon were critically examined, and the random adsorption model suggested by the author was found to provide the most complete explanation of available experimental data. Theory based on this model and containing one adjustable parameter (filler surface area per adsorption site) correctly predicts the change of molar mass distribution with adsorption on filler and satisfactorily describes the experimental dependence of fraction B of the filler-bound polymer on filler concentration and surface area and on M _w of the polymer, in both narrow and very broad molar mass distributions. No distinct effect on B of a moderate degree of branching of EPM, EPDM chains could be detected. It is concluded that the modification of the random adsorption model suggested by Shiga is not warranted, neither theoretically nor experimentally. © 1993 John Wiley & Sons, Inc.     

Study of autocorrelation function of polymer and polymer–nanocomposite solutions using dynamic light scattering method

Dynamic light scattering (DLS) of polymer and polymer–nanocomposite solutions has been performed to examine the effect in the morphology of polymer solution in presence of nanoparticles analyzing their correlation functions. The size of the nanoparticle was determined using UV–Vis absorption spectroscopy measurements. Analysis of the correlation functions of polymer solution shows existence of two modes, namely, fast and slow modes, along with the distinct values in their corresponding amplitudes and relaxation times. Interestingly, the fast mode of the solution was found to smear out, enhancing the slow mode when we grow nanoparticles into the polymer solution. Apart from the above study, the temperature variation study of both the solutions show that above and below room temperature, the polymer solution becomes more heterogeneous compared to the solution when nanoparticles are grown into it.     

Bonding of vapor deposited gold to glass using organosilane primers

Organosilane primers are known to improve adhesion of thin metal films deposited on inorganic and plastic surfaces. The present study demonstrated that the initial peel adhesion of vapor deposited gold to silane-primed glass substrate is greater than 3.5 N/cm estimated from cross-hatch test and thus is generally consistent with the earlier reports. The gold coated glass slides when examined using a more severe test (i.e. chemically bonding to a polymer, and subsequent peeling), however, exhibited poor adhesion in all cases except when the glass substrate was primed with an oligomeric organosilane primer. The successful primer (Dow Corning® 1205) was found to develop peel adhesion between vapor deposited gold and glass which was better than 17.5 N/cm.     

Flocculation of kaolin suspension with cationic polymer

Flocculation experiments have been carried out using cationic polymers and kaolin suspensions. The effects of polymer dosage, kaolin concentration, pH, agitation, molecular weight and charge density of polymer, concentration of polymer solution, and addition of inorganic salt were systematically examined. It was found that two optimal points of polymer dosage exist between 0 to 8 × 10^?3 kg/kg-kaolin. The flocs formed at each optimal dosage are different from each other in shape and in size. It is concluded that these two kinds of flocculation are respectively caused by the neutralization of the surface charge of the particles due to the adsorption of free polymer and by the incomplete neutralization owing to the presence of polymer droplets.     

Morphology of Polypropylene in Relation to Dye Diffusion

Diffusion coefficients of disperse dyes in polypropylene were found to be influenced by extrusion temperature and spherulite size. The assumption that sites in unmodified polypropylene do not exist is questioned. A correlation was observed between the number of polymer chain ends and saturation values for certain dyes and a polar interaction mechanism was proposed for such systems. The concept of fixing dye in the polymer by crystallizing the polymer was examined and found to be possible.     

The Effect of Comonomers on the Foaming Characteristics of Polypropylene

In the process of polypropylene (PP) polymerization, different kinds of PP are produced depending on the differences in the structural changes with the arrangement of comonomers. Each kind of PP has distinct properties, which arise from differences in the fundamental chain bonding structure of each polymer and affect not only the mechanical properties but also the foaming characteristics of each resin. Therefore, the fundamental foaming characteristics require experimental investigation. We examined the effects of PP polymerization on the foaming rate and solubility in the microcellular foaming process.     

Polymerization of methane

Plasma polymerization of methane in a magnetically enhanced capacitively coupled bell jar reactor operating at a frequency of 10 kHz is reported. Dependence of polymer deposition rate on monomer feed rate (F), composite power parameter (W/FM), electrode temperature, and electrode cleanliness have been examined. Such functional properties as wettability, adhesion, and thermal stability of the polymer are found to depend on the composite power parameter (W/FM) of the plasma. The permeability studies indicate highly crosslinked nature of the polymer. ESCA studies reveal codeposition of electrode material with the polymer under high W/FM conditions, potential applications of plasma polymer of methane are suggested.     

Investigating buried polymer interfaces using sum frequency generation vibrational spectroscopy

This paper reviews recent progress in the studies of buried polymer interfaces using sum frequency generation (SFG) vibrational spectroscopy. Both buried solid/liquid and solid/solid interfaces involving polymeric materials are discussed. SFG studies of polymer/water interfaces show that different polymers exhibit varied surface restructuring behavior in water, indicating the importance of probing polymer/water interfaces in situ. SFG has also been applied to the investigation of interfaces between polymers and other liquids. It has been found that molecular interactions at such polymer/liquid interfaces dictate interfacial polymer structures. The molecular structures of silane molecules, which are widely used as adhesion promoters, have been investigated using SFG at buried polymer/silane and polymer/polymer interfaces, providing molecular-level understanding of polymer adhesion promotion. The molecular structures of polymer/solid interfaces have been examined using SFG with several different experimental geometries. These results have provided molecular-level information about polymer friction, adhesion, interfacial chemical reactions, interfacial electronic properties, and the structure of layer-by-layer deposited polymers. Such research has demonstrated that SFG is a powerful tool to probe buried interfaces involving polymeric materials, which are difficult to study by conventional surface sensitive analytical techniques.     

Effects of crystallization on dispersion of carbon nanofibers and electrical properties of polymer nanocomposites

Polymer nanocomposites filled with low volume fractions of carbon nanofibers (CNFs) were prepared by melt‐compounding. Three types of polymers with different crystallization behavior, i.e., weakly‐crystallized low density polyethylene (LDPE), strongly crystallized high density polyethylene (HDPE) and amorphous polystyrene (PS), were selected as matrices for the nanocomposites. The effects of polymer crystallization on the dispersion of CNFs were examined. Optical and electron microscopic examinations revealed that the dispersion of CNFs in the nanocomposite matrices was strongly depended on the crystallization behavior of polymer matrices. The CNFs were found to disperse uniformly in weakly crystallized LDPE and amorphous PS matrices, but agglomerated in HDPE due to its strong crystallization tendency. Such a distinct dispersion behavior of CNFs in polymers had a profound effect on the electrical properties of the nanocomposites investigated. The PS/CNF nanocomposites exhibited the lowest percolation threshold. The HDPE/CNF nanocomposites showed the largest percolation threshold due to the CNF agglomeration within the amorphous phase of HDPE. POLYM. ENG. SCI., 48:177–183, 2008. © 2007 Society of Plastics Engineers     

Adsorption of poly (4‐sodium styrene sulfonate) on kaolinite clays

The adsorption of polymer on clay particles has great importance in many industrial applications. This work aimed to study the adsorption of anionic polymer, poly (4‐sodium styrene sulfonate), on kaolinite clay surfaces. Three different Egyptian kaolinite clay samples were used. The kaolinite clays were saturated with sodium or calcium cation. It was found that the Freundlich isotherm is applicable for this polymer adsorption on kaolinite. The parameters of the Freundlich equation are very close, indicating a comparable nature for the binding behavior between the different samples of kaolinite and the adsorbed polymer. The adsorption process was examined at different pH values (3, 6, and 9 ± 0.1) to cover the range below and above the point of zero charge of kaolinite surfaces. It was found that, below this point, the polymer adsorption increased, while above it the polymer adsorption decreased. The polymer adsorption on calcium kaolinite was higher than that of sodium kaolinite at the same pH value. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1712–1719, 2006     

INVESTIGATIONS ON TRANSITION TO TURBULENCE IN PIPE FLOW OF NEWTONIAN AND VISCOELASTIC FLUIDS**

The linear stability analysis of fully developed pipe flow of a second order and a “contravariant” Maxwell-type fluid predicts stability against twodimensional infinitesimal disturbances of rotational symmetry.

A sinuous perturbation, superposed on the pipe flow of aqueous polymer solutions, produces distinct regions of instability, dependent on disturbance amplitude and frequency.

A broad region of Reynolds numbers is found for natural transition to turbulence with laminarization effect of polymer additions in two extremely different cases of inlet conditions.     

Zum abbau von polymerlösungen durch kapillarscherung. Einfluß der kapillarlänge und strömungsform auf den abbau

The dependence of shear degradation of polymer solutions on capillary length at constant shear stress is investigated with solutions of poly(isobutylene) (M_vis=6,1 · 10⁶) in toluene. We examined concentrations of 0.1, 0.25, 1 and 4% and found the degradation to increase with capillary length. In 0,1% solution we found a decreased efficiency of degradation, due to a change in the structure of solution. Flow instabilities, which appear above a critical shear rate D in polymer solutions and pretend a loss in viscosity, are not caused by shear degradation. This result supports our interpretation of unstable flow of polymer solutions as slip flow (spurt).     

碳纤维增强树脂基复合材料性能的研究

以不同含量的二乙烯三胺(DETA)固化的环氧树脂为基体,制备了碳纤维增强树脂基复合材料。通过扫描电镜和红外光谱分析了T-300型碳纤维表面形貌和基团组成。通过拉伸实验、冲击实验对复合材料的力学性能进行了表征;通过紫外老化实验对复合材料的耐候性进行了表征;通过扫描电镜和热重分析对复合材料的断面形貌和耐热性进行了表征。结果表明:碳纤维增强树脂基复合材料具有良好的耐候性、力学性能、而且还具有质量轻、高比强度等一系列优异的性能。     

Shear yield behavior of calcium carbonate–filled polypropylene

The rheological properties of calcium carbonate-filled polypropylene has been examined using a Rheometrics dynamic analyzer RDAII. The study included a steady shear test, a transient stress growth test, and a dynamic oscillatory shear flow. Yield behavior was observed in all kinds of rheological tests for highly filled compounds when the volume loading exceeded a critical value at about 20%. The empirical Cox-Merz rule, which is usually applicable to an unfilled polymer, was found to be invalid for highly filled compounds. The modified Cox-Merz rule, in which the apparent viscosity versus the shear rate is equal to the complex viscosity versus the frequency-amplitude in the nonlinear region, was found to be valid only for highly filled compounds. The viscosity and the apparent yield values appear to increase with increasing volume loading of filler particles. The surface treatment of fillers, which presumably reduces the interaction between filler particles and the extent of agglomeration, results in major viscosity reductions and decreases in apparent yield values. The yield values determined from various tests are not the same. The results are interpreted in terms of a system forming a filler network due to weak inter-particle forces. The yield stress resulting from the breakdown and recovery of the network is thus dependent on the characteristic time of the individual test.     

Study of structural evolution during controlled degradation of ultrathin polymer films

The structural aspects of polyacrylamide thin films annealed at degradation threshold temperature have been studied as a function of annealing time using in situ X-ray reflectivity technique in vacuum. We observe significant decrease of thickness and increase of density with annealing time for all the films. The dynamical behavior of the changes was modeled in terms of two distinct exponential decay functions, following our earlier observation of two different time scales for the chemical modification pathways, and was found to be in excellent agreement with the data. The diffusion coefficients of the polymer chains corresponding to the two modes are found to be different by an order of magnitude. It was found that the two dynamical modes correspond to the formation of two degradation products at two different rates. The larger time constants for both the modes in case of thickness reduction compare to the chemical changes was explained in terms of inter-chain entanglement and attachment of the polymer with the substrate.