【作者】 赵春花；

【导师】 孙德军；

【作者基本信息】 山东大学 ， 胶体与界面化学， 2014， 博士

【摘要】 随着石油开采的不断进行,深层油气资源储量在能源中所占的比例越来越大。为了解决能源短缺、满足我国能源的需求,高效地勘探和开采深层油气资源已成为亟待解决的问题。基于深层油气资源开发中面临的高温、高盐等苛刻环境,作者通过大量的文献调研发现具有高电荷、高温下易与粘土吸附的磺酸基、羟基、胺基等强水化基团的水溶性聚合物能够维持和控制钻井液在高温、高盐条件下的滤失性和流变性能,因此研究高温、高盐下该类具有特定结构及功能基团的水溶性聚合物分子物理化学性质的变化及其与粘土颗粒之间的相互作用,能够为调控钻井液的各项性能及合成新型钻井液处理剂提供理论指导,有利于发展适用于深井和超深井的高性能钻井液技术,也是保护油气层、提高油气产量、提高油气勘探开发综合经济效益、满足环保等多方面的必然要求。近年来,为了提高钻井液的抗温抗盐性能,该领域的研究主要集中在具有特定结构及功能基团的新型水溶性聚合物分子的合成,以及室温下该类水溶性聚合物分子的物理化学性质及其与粘土颗粒之间的相互作用,得到了该类水溶性聚合物的物理化学性质随浓度、pH值、无机盐浓度、温度等因素变化的规律,深刻认识了这些因素对水溶性聚合物与粘土颗粒之间的相互作用的影响。尽管如此,我们注意到仍有许多问题需要进一步深入探讨：(1)低分子量的聚醚胺在粘土颗粒上的吸附机理与其分子结构的关系,以及在高温、高盐下聚醚胺对粘土颗粒分散体系稳定性的影响；(2)温度对低分子量聚醚胺与粘土颗粒之间的相互作用的影响,进而对端胺聚醚与粘土混合分散体系流变学性质的影响；(3)低分子量的磺化共聚物分子与无机盐的相互作用及其导致的聚合物分子构型、亲疏水性、界面活性以及乳化性能的变化；(4)仍需大量新的表征方法探讨具有高电荷、高温下易与粘土吸附的磺酸基、羟基、胺基等强水化基团的水溶性聚合物的结构与溶液特性的关系及其在水溶液中的聚集行为发生的机理。基于上述背景,本文选择了两类钻井液中常用的低分子量的水溶性聚合物一端胺聚醚和苯乙烯磺酸-马来酸酐共聚物(PSSMA)。首先,初步探讨了不同结构的端胺聚醚在蒙脱土颗粒上的吸附机理及其对粘土分散体系稳定性的影响,进一步考察无机盐加入或高温处理后端胺聚醚／粘土混合分散体系稳定性的变化并分析其原因。在此基础上,发现了端胺聚醚与蒙脱土混合体系的温敏凝胶化现象,考察了不同温度下端胺聚醚/蒙脱土混合分散体系流变学性能的变化并尝试解释了该混合体系出现溶胶-凝胶转变的机理。第四章探讨了无机盐诱导PSSMA分子构型、亲疏水性、界面活性以及乳化性能的变化,制备出钙离子敏感的Pickering乳液。丰富了高温高盐下聚合物分子物理化学性质变化的研究,提出了聚合物性质改变的可能机理,明确了聚合物性质的改变对粘土分散体系胶体稳定性的影响。本文的主要内容包括以下三个部分：1.端胺聚醚对蒙脱土悬浮液胶体稳定性的影响对比研究了含有相似数目氧乙烯基团(EO)的端胺聚醚JeffamineM1000(M1000)和聚乙二醇PEO在蒙脱土颗粒上的吸附及对粘土体系胶体稳定性的影响。首先,我们利用总有机碳分析仪测定了M1000和PEO在蒙脱土颗粒上的吸附等温线,结合文献和实验给出了两者在蒙脱土颗粒上的吸附机理。通过X射线粉末衍射、Zeta电位、流变、沉降观察和透射电子显微镜(TEM)等手段表征了M1000和PEO对蒙脱土分散体系影响的异同,并且利用相互作用势能曲线解释了M1000和PEO的吸附构象对粘土分散体系抗盐性的影响。实验结果证实,M1000分子主要以末端的极性胺基通过静电作用吸附在粘土颗粒表面,使得EO基团伸向体相溶液中,从而在粘土颗粒表面形成浓密堆积的类似蘑菇的构象,提高了粘土分散体系的抗盐性并维持了高温老化处理后粘土分散体系的稳定性和流变学性能。相应地,PEO分子主要通过氢键作用吸附在粘土颗粒上,并采取平躺的构象,不能有效地提高粘土分散体系的抗盐性,而且还会导致高温老化处理后的粘土分散体系发生桥联絮凝,恶化了高温处理后粘土分散体系的流变学性能。这种聚合物末端结构的不同导致胶体分散体系性质的改变,可以用来指导分散体系胶体稳定性的调控,而且在特殊的应用领域如钻井液和水处理有着潜在的应用前景。2.端胺聚醚与蒙脱土混合体系的温敏凝胶行为的研究通常聚合物与粘土的混合体系表现为低温粘度增大而高温粘度降低的特点,而端胺聚醚与蒙脱土的混合体系则表现出相反的粘温效应,即低温粘度降低而高温粘度增大。当端胺聚醚和蒙脱土按照一定比例混合时,会出现温敏凝胶化的现象。在较低的温度时,吸附在粘土颗粒表面上的聚氧乙烯(PEO)或聚氧丙烯(PPO)嵌段的溶解性较好,能够有效地伸展并提供空间位阻作用,使得粘土分散体系稳定,形成低粘度的溶胶。随着温度的升高,PEO或PPO嵌段发生去水化,在水中的溶解性降低,伸展的PEO或PPO嵌段逐渐发生卷曲；当超过临界转变温度时,粘土分散体系由溶胶转变为凝胶,对应的表观粘度增大,且这种溶胶-凝胶的转变是可逆的。此外,随着端胺聚醚分子中EO或PO基团的数目增多,该溶胶-凝胶转变的临界温度升高。根据对胶体颗粒之间的相互作用力的定性分析,发现端胺聚醚修饰的粘土颗粒的相互作用势能曲线上存在着一个较弱的吸引势能(第二极小值)。随着温度的升高或者端胺聚醚分子量的降低,空间稳定层的厚度减小,吸引势能的势垒增加,导致端胺聚醚与蒙脱土的混合体系在远离0温度条件下发生溶胶-凝胶的转变,由于该吸引势能的势阱较浅,所以混合体系溶胶-凝胶转变具有可逆性,这一特性使得此类温敏智能凝胶体系在钻井堵漏过程中有着巨大的应用前景。3.钙离子诱导PSSMA形成可逆的纳米聚集体及其响应的Pickering乳液磺化聚合物由于其电荷密度高,不受分散介质pH值的影响,以及良好的降滤失效果被广泛应用于油气钻探方面,而由高温高盐导致的磺化聚合物去水化和聚集会引起深井钻探时钻井液性能的恶化,因此研究高温、高盐下磺化聚合物物理化学性质的变化具有重要意义。本章研究了苯乙烯磺酸-马来酸酐共聚物(PSSMA)与钙离子的结合对该结合引起的分子尺寸、亲水性和界面活性的变化。利用动态光散射、低温透射电镜、荧光芘探针和动态界面张力仪等手段对加入氯化钙后磺化聚合物水溶液的性质进行了表征。随着钙离子浓度的增加,PSSMA分子的尺寸先减小后增大,当超过临界钙离子浓度0.2mol/L时,在水溶液中形成纳米聚集体,其平均粒径在10-40nm。用纯水稀释后,PSSMA纳米聚集体又重新溶解。基于PSSMA纳米聚集体的这一特性,我们成功制备了钙离子响应的Pickering乳液。当钙离子浓度较高时,形成的PSSMA纳米聚集体颗粒能够吸附在油水界面上,有效地降低界面张力,从而形成稳定的纳米尺度的Pickering乳液；而通过简单的纯水稀释,体系中钙离子浓度下降,PSSMA纳米聚集体又解离为单个的聚合物分子,使得聚集体颗粒从油水界面上脱附,导致乳液的稳定性快速下降。低温透射电镜和动态界面张力证实了PSSMA纳米聚集体在乳液滴表面的吸附。乳液的显微镜照片也清楚地表明了乳液的稳定性与钙离子浓度之间的关系。因此认为制备的Pickering乳液是钙离子浓度响应的,为调控乳液稳定性提供了一种新的方法。更多还原

【Abstract】 With the ongoing exploration of oil, the proportion of oil and gas resources in deep strata is becoming larger and larger. In order to meet the increasing demand for oil energy, the efficient exploration and exploitation of oil and gas resources in deep strata are of particular importance. Based on investigation of a large number of related literatures in detail, the water-soluble polymer with-SO3H,-NH2, or-OH groups are usually used to effectively regulate and control the rheology and filtration loss under high-temperature and high-salinity. Therefore, the investigation of the physical and chemical properties of the above polymer molecules in solution under high-temperature and high-salinity and their effects on the colloidal stability of montmorillonite suspensions is the key technology to design and produce the high-temperature resistant water-based drilling fluids. It is very important for the development of the ultra-deep drilling technology and the application of oil consumption in such a large demandent country. What is more, it could accelerate the speed of China’s oil and gas exploration and development, to ensure self-sufficiency ratio of oil and gas resources in China and the country’s energy security.Recently, researchers focus on the developing new drilling fluid additives with good performance through polymerization with molecular structure design. They also studied the effects of polymer concentration, pH, salt concentration and temperature on the physical and chemical properties of the above polymer molecules in solution at room temperature and their influences on the colloidal stability of montmorillonite suspensions. However, there are still some problems in the following aspects. Firstly, the adsorption mechanism of polyetheramine on montmorillonite particles and its influences on the colloidal stability of montmorillonite suspensions are not fully understood. Secondly, the effect of temperature on the rheology behaviors of aqueous solutions containing polytheramine and montmorillonite particles should be studied in detail. Thirdly, the influences of high-salinity on the properties of sulfonated polymers are not clear. Finally, more methods should be explored to investigate the effects of high-temperature and high-salinity on the properties of water-soluble polymer in solutions.Based on the above discussion, in this dissertation, two kinds of water-soluble polymers with low molecular weight, polyetheramine and styrene sulfonic acid maleic anhydride copolymer (PSSMA) are investigated. First, the adsorption mechanism of polyetheramines on montmorillonite particles and their effects on the colloidal stability of montmorillonite suspensions after high temperature treatments or in the presence of salts are studied. Second, by investigating the rheology behavior of montmorillonite dispersion with polyetheramine under different temperatures, thermogelling in polyetheramine/montmorillonite suspensions are studied in detail. In addition, the physical and chemical properties of PSSMA molecules in the presence of Ca2+ions are investigated systematically, including the aggregation of PSSMA molecules and the interfacial activity.The present dissertation includes three topics.1. Colloidal properties of montmorillonite suspensions modified with polyetheramineA systematical evaluation of a polyetheramine (Jeffamine M1000) and polyethylene oxide (PEO), which have a similar number of ethylene oxide units and molecular weight, on modulating colloidal stability of montmorillonite suspensions exposed to high temperature (120℃,16h) or salt conditions are performed. A varied of methods including measurement of adsorption, X-ray diffraction (XRD), zeta potential, transmission electron microscopy (TEM), settlement experiments and rheology measurements are used to illustrate the difference. Results indicate that M1000molecules adsorb onto the particles mainly through electrostatic interaction and adopt a densely packed mushroom configuration on the clay surface. Because of the adsorption properties of M1000, the salt tolerance is improved slightly (from10mmol/L to50mmol/L NaCl) and the colloidal stability of the high temperature treated suspensions is maintained. Meanwhile, PEO molecules adsorb onto clay via hydrogen bonding and take a compact conformation on the clay surface, which could not improve the salt tolerance effectively and leads to a weak bridging flocculation at high temperature. Thus, this finding not only provides some new guidance on modulating the colloidal stability of dispersion but also would be very useful in specific applications, such as drilling fluids and water treatment.2. Thermoreversible gelation in montmorillonite suspension containing polyetheramineMost types of structured complex fluids tend to decrease in viscosity with increasing temperature. However, in polyetheramine/montmorillonite mixed system the polymer-liquid affinity is strongly influenced by temperature, and as a result, unusual behaviors occur in the microstructure of dispersions upon heating. At low temperature (5℃), water is a good solvent for PEO and PPO chains of polyetheramine molecules adsorbed on montmorillonite particles, and the dispersion is a stable, low-viscosity sol. With the increase of temperature, water becomes a progressively worse solvent for PEO and PPO chains. Beyond a critical temperature (Tc), there is a sharp transition in microstructure from a stable sol to a volume-filling gel. The sol-gel transition is reversible, which requires each component to be present in certain percentage. Remarkably, the gelation occurs under significantly better than0temperature, which nearly equals the lower consolute solution temperature for PEO and PPO chains in water. Tc is strongly influenced by the chain length of PEO and PPO. The longer the PEO chains, the higher the Tc for gelation. We attribute the onset of thermogelling to the secondary minimum in the interparticle potential that can develop in the case of short stabilizing moieties and moderate solvent conditions. Owing to the modulating of the microstructure upon heating, this finding provides theoretical basis and guidance for filed application of the plugging principle and technology of gel sug.3. Ca2+ion responsive Pickering emulsions stabilized by PSSMA nanoaggregatesSulfonated polymers are a variety of strong water-soluble anionic polyelectrolytes with high charge density, good dispersion property in aqueous solution, without pH control and good surface and interfacial activities. They are often used in oil and gas drilling, whose dehydration and aggregation frequently brings about the difficulty of losing control of drilling fluid filtration at the elevated temperatures and salt concentrations. Therefore, the investigations of the physical and chemical properties of the sulfonated polymer molecules in solution under high-temperature and high-salinity are important. This topic is mainly focused on the interaction between Ca2+and Poly (4-styrenesulfonic acid-co-maleic acid) sodium salt (PSSMA) molecules and its effect on the physical and chemical properties of PSSMA molecules. Results from dynamic light scattering (DLS) and cryo-transmission electron microscopy (cryo-TEM) indicate that the formation of PSSMA nanoaggregates is strongly dependent on Ca2+concentration. The PSSMA copolymer only aggregates above a critical Ca2+concentration (0.2mol/L) with an average diameter of10-40nm. After dilution with water, PSSMA nanoaggregates are rapidly redissolved again. Based on the properties of PSSMA nanoaggregates, Ca2+ion responsive Pickering emulsions were successfully prepared. At high Ca2+concentrations, the emulsions with high stability against coalescence can be prepared with the size in the submicrometer range as determined by DLS. Cryo-TEM and dynamic interfacial tension results confirm the adsorption of PSSMA nanoaggregates at the interface, which is the key to the stability of the emulsions. More importantly, rapid demulsification can be achieved by dilution with water on demand. It is because that upon dilution with water, PSSMA nanoaggregates undergo a transition from stable nanoaggregates to individual polymer chains, which leads to interfacial desorption of nanoaggregates and rapid demulsification of emulsions. Thus, this finding presents a new manipulation on emulsion stability and is expected to provide a useful guidance in the field of oil recovery, food science, environment protection and so on.更多还原