烷基酰胺丙基甜菜碱的一锅法合成及表面性质

以三种脂肪酸、N,N-二甲基丙二胺及氯乙酸钠为原料,通过一锅法合成了三种烷基酰胺丙基甜菜碱。在脂肪酸与N,N-二甲基丙二胺的酰胺化反应过程中,最佳反应温度为160℃,优化反应时间为9 h条件下,脂肪酸反应转化率>95%。进一步加入氯乙酸钠进行季铵化反应,优化反应温度为70℃,反应时间为4 h。在上述反应条件下,通过一锅法合成了月桂酸基、油酸基和芥酸基三种甜菜碱表面活性剂,收率>80%。三种甜菜碱均具有良好的表面活性,随烷基链增长,临界胶束浓度降低。此外,三种表面活性剂的临界胶束浓度受Na^(+)、Ca^(2+)和Mg^(2+)影响较小,表现出优异的抗离子能力。

海水基聚丙烯酰胺高温冻胶体系的研制与性能评价

南海A油田注气开发中,油井气油比急剧增大,气窜明显,为此开展了海水基高温冻胶封窜体系研究。选用非离子聚丙烯酰胺(NPAM)和酚醛体系作为主剂和交联剂,探索增大聚合物浓度、加入除氧剂和高温稳定剂3种方式增强冻胶高温稳定性效果;形成了海水基高温冻胶体系配方,并考察了其对天然气的耐受性和封堵能力。结果表明:尽管采用高浓度聚合物能够增强冻胶热稳定性,但在125℃下,即使采用高浓度(0.8%)NPAM,冻胶老化48 h后脱水率在90%以上;除氧剂的加入也难以显著改善冻胶热稳定性;高温稳定剂可明显增强冻胶的耐温性,是构筑海水基高温冻胶体系的关键组分。优化形成的海水基高温冻胶体系配方为:0.4%NPAM+0.3%乌洛托品+0.3%间苯二酚+0.8%稳定剂。该体系在125℃下的成胶时间为10~12 h,60 d内仍能维持较好冻胶状态,不破胶;弹性模量大于1500 mPa,脱水率小于10%。冻胶能在高温高压环境下与天然气稳定共存,不破胶;冻胶能对岩心形成良好封堵,稳定残余阻力系数210,封堵率99.5%,且耐冲刷性较强。

Surfactant induced reservoir wettability alteration:Recent theoretical and experimental advances in enhanced oil recovery

Reservoir wettability plays an important role in various oil recovery processes.The origin and evolution of reservoir wettability were critically reviewed to better understand the complexity of wettability due to interactions in crude oil-brine-rock system,with introduction of different wetting states and their influence on fluid distribution in pore spaces.The effect of wettability on oil recovery of waterflooding was then summarized from past and recent research to emphasize the importance of wettability in oil displacement by brine.The mechanism of wettability alteration by different surfactants in both carbonate and sandstone reservoirs was analyzed,concerning their distinct surface chemistry,and different interaction patterns of surfactants with components on rock surface.Other concerns such as the combined effect of wettability alteration and interfacial tension （IFT） reduction on the imbibition process was also taken into account.Generally,surfactant induced wettability alteration for enhanced oil recovery is still in the stage of laboratory investigation.The successful application of this technique relies on a comprehensive survey of target reservoir conditions,and could be expected especially in low permeability fractured reservoirs and forced imbibition process.

Effects of Shear Fracture on In-depth Profile Modification of Weak Gels

Two sand packs were filled with fine glass beads and quartz sand respectively. The characteristics of crosslinked polymer flowing through the sand packs as well as the influence of shear fracture of porous media on the indepth profile modification of the weak gel generated from the crosslinked polymer were investigated. The results indicated that under the dynamic condition crosslinking reaction happened in both sand packs, and the weak gels in these two cases became small gel particles after water flooding. The differences were： the dynamic gelation time in the quartz sand pack was longer than that in the glass bead pack. Residual resistance factor （FRR） caused by the weak gel in the quartz sand pack was smaller than that in the glass bead pack. The weak gel became gel particles after being scoured by subsequent flood water. A weak gel with uniform apparent viscosity and sealing characteristics was generated in every part of the glass bead pack, which could not only move deeply into the sand pack but also seal the high capacity channels again when it reached the deep part. The weak gel performed in-depth profile modification in the glass bead pack, while in the quartz sand pack, the weak gel was concentrated with 100 cm from the entrance of the sand pack. When propelled by the subsequent flood water, the weak gel could move towards the deep part of the sand pack but then became tiny gel particles and could not effectively seal the high capacity channels there. The in-depth profile modification of the weak gel was very weak in the quartz sand pack. It was the shear fracture of porous media that mainly affected the properties and weakened the in-depth profile modification of the weak gel.

音乐神经反馈改善大学生阈下抑郁状态研究

阈下抑郁是指达不到抑郁症诊断标准的以抑郁心境为主的心理亚健康状态,适度干预可以改善其状态,降低病情发展风险。本文针对音乐神经反馈改善大学生阈下抑郁状态展开研究。24名阈下抑郁大学生参与本次试验,其中16名为试验组成员。采用基于频谱分类的解压类音乐对16名试验组成员进行10 min/d,周期为14 d的音乐神经反馈刺激,8名对照组成员不做任何刺激。本文提取并分析受试者脑电信号的相对功率、样本熵、复杂度共3个特征参数。研究结果表明,经音乐神经反馈刺激后,试验组人员的α、β、θ节律相对功率增大,δ节律相对功率减小;样本熵和复杂度均显著提高,且差异具有统计学意义(P<0.05);对照组特征参数差异均无统计学意义。试验组经音乐神经反馈刺激后,抑郁自评量表(SDS)得分减少,表明抑郁情绪得到改善。本研究结果表明,音乐神经反馈刺激可以改善阈下抑郁情绪,今后或可为大学生情绪自我调节提供一种有效的新思路。

Experiment and simulation study on construction of a three-dimensional network model

The construction of a network model is one of the key techniques in organic com-bination of microscopic flow experiment and simulation. The construction method of a three-dimensional network model is presented on the basis of CT scanning images in this paper. A series of CT slice images describing microscopic pore structure and fluid distribution of actual rock is obtained with the help of the in-dustrial microfocus CT system. Based on the extraction of pore space skeleton, pore and throat information, the corresponding network model is established, and the conversion from three-dimensional CT image information to pore-throat size distribution and topological information is also achieved. The feature of this me-thod lies in the fact that complicated pore space of rock may be characterized by pores and throats with a simple shape while keeping the geometry and flow char-acteristics. It is indicated that the calculated results of porosity, permeability, rela-tive permeability curve and microscopic remaining oil distribution match very well the experimental results of water flooding and polymer flooding. This network model may fairly well characterize the rock microscopic pore-throat size and topo-logical characteristics.

Supramolecular vesicles of cationic gemini surfactants modulated by p-sulfonatocalix[4]arene

Supramolecular binary vesicles were constructed by host-guest complex formation between p-sulfonatocalix[4]arene and three cationic gemini surfactants, which were identified by UV-vis, dynamic laser scattering, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, and surface tension experiments. The critical aggregation concentration of gemini surfactants decreased pronouncedly by a factor of ca. 1000 owing to the complexation of p-sulfonato-calix[4]arene.