基于微流控模型的致密油藏微观渗吸机制试验

针对目前岩心渗吸周期长、计量不准确且现有微观模型参数设计未涉及到致密储层典型喉道尺寸等问题,设计考虑不同喉道尺寸、孔隙形状、孔喉比、喉道与孔隙连接位置、配位数玻璃制成的喉道和孔隙双深度及硅-玻璃制成的均深刻蚀微流控模型,并通过高温氧化硅镀层实现流道内部润湿性一致,开展蒸馏水-油、油-异丙醇-蒸馏水型体系的一系列渗吸试验。结果表明:喉道中存在薄膜流动,且薄膜流动速度远快于渗吸弯液面移动速度,不规则渗吸界面是由喉道内表面粗糙度引起的,薄膜流动对孔喉渗吸效果影响显著;渗吸早期,宽喉道对于渗吸作用的贡献远大于窄喉道,润湿性增加有利于润湿相向扩径区域渗吸;薄膜流动避免了润湿相在喉道中的卡断现象,而是以间断薄膜流动形式继续向出口流动;较小的润湿角和迂曲度有利于渗吸作用,渗吸的距离更远,渗吸前缘更为均匀,配位数、孔隙形状及大小对渗吸影响较小,主要受孔隙与喉道接触位置的开口大小决定,润湿性决定渗吸在各种孔喉结构下的整体效果。

渤南区域中轻质油田相渗规律影响因素研究

相渗透率研究是油田开发方案编制和生产管理不可缺少的基础工作,在注水开发油田中,由于中轻质油田相对稠油油田具有较长的无水采油期或低含水期,而常规的非稳态实验中相渗数据点在中高含水饱和度处较为集中,因此采用此方法获取的相渗数据直接应用到中轻质油田生产动态分析及数模拟合中误差较大。针对以上问题,对渤南区域中轻质油田分别采用稳态与非稳态两种实验方法获取相渗数据并开展研究,结果表明:当地层原油黏度小于6 m Pa·s时,两种实验方法结果差异较大,宜采用稳态法;当原油黏度高于6 m Pa·s时,差异可忽略不计,宜采用非稳态法代替稳态法。研究发现,非润湿相黏度、沉积相特征、润湿性、温度等因素对中轻质油藏相渗曲线形态及含水上升规律都有不同程度的影响,在油田开发研究中应综合考虑。

利用IFT变化测量三相相对渗透率

本文描述不同界面张力（IFT）对三相相对渗透率影响的实验研究结果。报道三相中两相间低界面张力对三相相对渗透率影响的实验证明结果。 为建立界面张力可以系统控制的三相体系，用十六烷、正丁醇、水和异丙醇四种液体组成的体系。报道平衡相组分和IFT的测量，报告的四种流体组成的体系相特性表明：富水相可能代表“气”相，富正丁醇相可能代表“油”相，富十六烷相可能代表“水”相，因此，我们用油湿特氟隆人造岩心模拟流体在水湿油藏中流动。根据联合使用Welge／Johnson—Bossier—Naumann法和三相流理论推导得到的采收率和压差数据确定相饱和度和三相相对渗透率。报道了所测量的三相相对渗透率。 实验结果表明润湿相的相对渗透率不受IFT变化影响，而其它两相则明显受到影响。随着IFT的下降，相同饱和度的油、气相更易流动。对于油气IFT在0．03—2．3范围来说，我们发现IFT下降近100倍，油气相对渗透率增加约10倍。

基于MS-P方法的不规则管内流体的分布研究

提出了一种新的基于单角毛细管的模型。在该模型中,当非润湿相注入已经饱和润湿相的毛细管中时,不混溶的两相的分布是由一个特定的阈值压力所确定。利用Young-Laplace方程,推导和分析了不同管内流体间界面的曲率和弯液面的形状;并通过叠加单角毛管模型生成不同多边形毛管模型,研究边的多边形数和流体分布之间的关系,以及等边多边形毛管中润湿相的饱和度。在单角毛细管的基础上,研究了角的位置对于润湿相分布的影响;并分析了流体界面在角的相互影响的五个阶段分布特点。

低压气藏堵水技术研究

气井产水是很普遍的生产现象,具有很大的危害。通过堵水处理能有效降低产水量。而油井常规的堵水方法效果又不尽如人意,因此需要根据气井非润湿相(即气相)的特点,研究合适的气井专用堵水剂。

Development of Al-12Si-xTi system active ternary filler metals for Al metal matrix composites

To improve the wettability of Al metal matrix composites（Al-MMCs） by common filler metals,Al-12Si-xTi（x=0.1,0.5,1,3.0;mass fraction,%） system active ternary filler metals were prepared.It was demonstrated that although the added Ti existed within Ti（Al1-xSix）3（0≤x≤0.15） phase,the shear strength and shear fracture surface of the developed Al-12Si-xTi brazes were quite similar to those of traditional Al-12Si braze due to the presence of similar microstructure of Al-Si eutectic microstructure with large volume fraction.So,small Ti addition（～1%） did not make the active brazes brittle and hard compared with the conventional Al-12Si braze.The measured melting range of each Al-12Si-xTi foil was very similar,i.e.,580-590 ℃,because the composition was close to that of eutectic.For wettability improvement,with increasing Ti content,the interfacial gap between the Al2O3 reinforcement and filler metal（R/M） could be eliminated,and the amount of the remainder of the active fillers on the composite substrate decreased after sessile drop test at 610 ℃ for 30 min.So,the wettability improvement became easy to observe repeatedly with increasing Ti content.Additionally,the amount and size of Ti（AlSi）3 phase were sensitive to the Ti content（before brazing） and Si content（after brazing）.

离心机法测定毛管压力特性曲线径向误差对精度的影响

众所周知,通过离心机法实验所获得的毛细管压力特性曲线其精确性很大程度上取决于原始资料的可靠性、岩样的均质性和数据的处理方法等,但确没有充分考虑到离心机方面的径向性质引起的系统误差。本文论述了径向误差可能比简要的数据处理引起的误差大。根据离心机转盘的几何形状和岩样的空间形态可以估计径向误差,精确的实验技术能减少径向误差,而且,在数据处理中,若适当地考虑离心机的径向性质,也能避免径向误差。

聚乙二醇400在氮化硅凝胶注模悬浮液中的应用(英文)

聚乙二醇 400(polyethylene glycol 400, PEG400)作为润湿剂用于制备高浓度氮化硅悬浮液,以简单的工艺,在降低料浆黏度的同时提高其固相含量。为表征润湿剂对高固相含量下氮化硅悬浮液的润湿特性,测试了其黏度及在润湿剂作用下的润湿性和吸附特性。结果表明:当悬浮液固相含量高达 60%(体积分数)时,在 PEG400 作用下其黏度可以显著降低。基于悬浮液中颗粒堆积形式,建立了等径密堆双球模型,阐释了 PEG400作用机理。

Gas–liquid two-phase flow in serpentine microchannel with different wall wettability

Gas–liquid flow in serpentine microchannel with different surface properties exhibits drastically different flow behavior. With water and air as working fluids, the method of numerical simulation was adopted in this paper based on CLSVOF(coupled level set and volume of fluid method) multiphase model. After verifying the reasonability of the model through experiment, by changing wall properties and Re number(Re<1500), the influences of contact angle and surface roughness on flow regime and Po number were discussed. Moreover, the difference of pressure drop between curve and straight microchannel was also calculated. Beyond that, the combined effect of curve channel and wall properties on flow resistance was analyzed. This paper finds that wall properties have great influence on gas–liquid flow in microchannels not only on flow regime but also flow characteristics. Meanwhile, the pressure drop in curve microchannels is larger than straight. It is more beneficial for fluid flowing when the straight part of microchannel is hydrophilic smooth wall and curve part is hydrophobic with large roughness.

Alkylpolyglycoside inducing poly (butylene terephthalate) non-woven graft copolymerization of chitosan

In order to improve the wettability and biocompatibility of the poly （butylene terephthalate） non-woven （PBTNW）, the method of surface modification is used to graft copolymerization of chitosan （CS） onto the PBTNW under alkylpolyglycoside （APG） inducing. The product is thoroughly characterized with the Fourier transform infrared spectroscopy （FrIR）, the electron spectroscopy for chemical analysis （ESCA）, the thermogravimetric （TG） and the scanning electron microscopy （SEM）. It is found that chitosan is successfully grafted onto PBTNW. In addition, the water contact angles, hemolysis tests and cytotoxicity evaluation tests show an improvement in wettability and biocompatihility as a result of graft copolymerization of chitosan. So the CS-grafted PBTNW exhibits greater superiority than the original PBTNW. The CS-grafted PBTNW can be a candidate for blood filter materials and other medical applications.

Displacement behavior and mechanism of long-term water flooding in sandstone oil reservoirs

Sandstone oil reservoirs with huge bottom water and high permeability are generally developed with high flow rate.After long-term water flooding(LTWF),the water flooding characteristics are quite different from that of original reservoir.In this paper,the effects of the PV number,viscosity,and displacement rate during LTWF are studied through experiments.The mechanism is analyzed based on analysis of changes in oil composition,rock mineral composition and wettability.The oil-water relative permeability curves,oil recovery and wettability were obtained with new experiments methods,which avoids the oil metering error by measuring oil and water separately.The research indicates that when the viscosity increases,the water phase permeability decreases,the residual oil saturation increases,and the water content rate increases earlier.A higher water flooding rate results in a higher ultimate recovery.A higher asphaltene content results in a higher viscosity and more oil-wet reservoir conditions.After LTWF,the wettability tends to water-wet,which is more favorable for heavy oil recovery.Moreover,LTWF reduces the clay content,which creates a more water-wet surface and a larger reservoir pore throat environment.This research provides insightful characteristics of offshore sandstone oil reservoirs,which can be used to enhance oil recovery.

Ti-6Al-4V合金β→α相变中晶界α相形成机制的相场模拟

使用相场模型研究了Ti-6Al-4V合金在β→α相变过程中晶界α相(αGB)的形核及晶界润湿生长过程。通过耦合Thermo-Calc热力学数据与相场模型模拟出的组织与实际形貌一致。结果表明,特殊构造的噪声项使β/β晶界处失稳,并促进α相在晶界上的形核。相变初期析出的α相颗粒较多的情况下生成的αGB形貌为连续的平滑状;反之,较少的α初始核会导致不连续αGB的生成,模拟结果揭示了实验中不同形貌αGB的形成机制。晶界润湿由不完全润湿到完全润湿可以是一个连续过程而不需其它反应即可实现。随噪声时间从50 s延长到80 s,αGB晶界润湿速率越来越快,且α相的体积分数逐渐增大;随噪声强度由0.05增大到0.11,反应速率也逐渐加快,而α相体积分数可能先增大后减小。噪声时间与强度对αGB形貌影响的规律与实验观察到的不同条件下的αGB形貌一致,可为晶界α相及合金的疲劳性能的控制提供信息。

Water wettability in nanoconfined environment

Water confined in nanoscale space behaves quite differently from that in the bulk.For example,in biological aquaporins and in carbon nanotubes,the traversing water molecules form a single file configuration.Water would stay in vapor state in extremely hydrophobic narrow nanopores owing to the physicochemical interactions between the water molecules and the surface of the nanopore.A spontaneous wet-dry transition has been identified in both biological and artificial nanopores.The nanopore is either fulfilled with liquid water or completely empty.Based on this mechanism,the wetting and dewetting processes inside nanopores have been further developed into highly efficient nanofluidic gates that can be switched by external stimuli,such as light irradiation,electric potential,temperature,and mechanical pressure.This review briefly covers the recent progress in the special wettability in nanoconfined environment,water transportation through biological or artificial nanochannels,as well as the smart nanofluidic gating system controlled by the water wettability.

Thermal-induced transformation of wetting behaviors on laser-textured SiC surfaces

Thermal-induced transformation of wetting behaviors on laser-textured silicon carbide （SIC） surfaces was discussed in this work. To investigate the transformation, a quenching experiment was conducted and an X-ray diffractometer was used to measure the residual stress. The experimental results demonstrate that the significantly enhanced hydrophilicity was induced by the increasing thermal residual stress of SiC materials after the aqueous quenching. It was found that the decrease in the contact angle increased with the increasing quenching temperature. Quenching at 350℃ led to the change of contact angle from 89.28° to 70.88° for the smooth surface, while from 72.25° to 33.75° for the laser-textured surface with depth 8 μm. Further, the surface hydrophobicity was enhanced by the release of thermal residual stress after quenching, thereby leading to an increase in the contact angle over time. The transformation of wetting behaviors on laser textured SiC surfaces can be achieved mutually by the aqueous quenching method.

Interactions between natural biofilm,substratum surface wettability,and mussel plantigrade settlement

Mytilus galloprovincialis is a major fouling organism in the inter-tidal zone.However,the interactions between M.galloprovincialis plantigrade settlement,biofilm characteristics,and surface wettability remains unknown.Here,we examined M.galloprovincialis plantigrade settlement responses to marine biofilms(BFs)on surfaces of varying wettability.No significant difference in mussel settlement was observed on young BFs(7 d)on surfaces of differing wettability;while settlement decreased on older BFs(14,21,and 28 d)formed on low compared to high wettability surfaces.Surface wettability affected BF characteristics.The standardized harmonic mean and water contact angles values were not correlated with diatom density and chlorophyll a concentration,but were correlated with bacterial density,dry weight,and thickness.Denaturing gradient gel electrophoresis revealed that bacterial community structure differed on BFs on surfaces of varying wettability.Thus,surface wettability affects biofilm characteristics,and the subsequent changes in BF characteristics may be responsible for the variation in biofilm-inducing activity of M.galloprovincialis plantigrade settlement.