A study of the properties of hydrophobically associating water-soluble polymers used in drilling fluids

Hydrophobically associating water-soluble polymers (HPAP) have been synthesized from acrylamide(AM), acrylate (AA), 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and hydrophobic monomer (AP) in aqueous solution by radical polymerization. New polymer drilling fluids are made up of HPAP, which is used as viscosifiers and encapsulation agents. Properties of this system are reported in this paper. Results indicate that this system has a high value of yield point to plastic viscosity (YP/PV≥0.7), high viscosity at a low-shear rate (LSRV≥30000mPa·s), excellent shear thinning behavior, good solid-carrying behavior, resistance to shear, good thermal stability (as high as 140℃) and salt resistance. The system has excellent behavior in high-density solution of NaCl and in calcium and magnesium rich saline solutions. Hence, HPAP also can be used in saltwater polymer drilling fluids.

SYNTHESIS AND CHARACTERIZATION OF A NOVEL FLUORINE-CONTAINING HYDROPHOBICALLY ASSOCIATING POLYMER

In this article, the synthesis and characterization of a novel fluoromonomer and its copolymer with acrylamide is reported. 2-perfluoroamyl-4-hydroxylquinoline 2 was synthesized from ethyl 2, 2-dihydroperfluoroheptanoate in high yields. The monomer 4 was then synthesized from 2 in two steps readily in high yields. Synthesis and characterization of copolymers of acrylamide (AM) and the fluoromonomer were investigated. The composition and intrinsic viscosity of these copolymers were studied. It was found that the rheological properties of aqueous solutions of polyacrylamide were modified significantly when a small proportion of the fluoromonomer 4 was incorporated on investigating the viscosity-concentration profiles, pseudoplasticity of these solutions and the effect of the presence of surfactant. These results could be explained by the hydrophobic association of the fluorocarbon segments in the aqueous solutions of these copolymers.

Synthesis and Solution Properties of Hydrophobic Associating Polymers

Acrylamide/2-acrylamido alkane sulfonic acid hydrophobic associating copolymers were synthesized by micellar copolymerization. Effects of hydrophobe content, polymer concentration, salinity and surfactant on rheological behavior of copolymers were investigated and the conformation of polymers in solution was studied by means of environmental scanning electronic microscopy and dynamic light scattering. The experimental results showed that in the dilute regime the hydrophobic parts could interact intramolecularly, while in the regime where the polymer concentration was higher than the critical association concentration, intermolecular hydrophobic association became predominant. Within the limit of the solubility, the critical association concentration of the polymer decreased with the increase of the salinity. The experimental results of the solution conformation indicated the presence of the three-dimensional network structure in deionized water and the size of the mesh in the network varied with the polymer concentration. In NaCl solution, above the critical association concentration, an increase in polymer concentration enhanced the intermolecular association and also enlarged the hydrodynamic radius. It would result in the improvement of the thickening power of polymers.

Rheological Properties of Hydrophobically Associating Polyacrylamide Solution

A temperature-resistant, salt-tolerant polyacrylamide, hydrophobically associating polymer （HAP）, was synthesized in the State Key Laboratory of Heavy Oil Processing. The rheological behavior of HAP solution was investigated by means of flow experiments in porous media and by using a HAAKE RS600 rheometer. The results of Nuclepore membrane filtration showed that filtration time increased sharply when the critical association concentration was reached. Shear rate had a greater impact on viscosity and shear stress with increasing HAP concentration. The HAP solution with a concentration of 100 mg/L （salinity 32,868 mg/L） exhibited negative thixotropy. However, at the same salinity the HAP solution showed thixotropy and its viscosity became greater when the polymer concentration increased to 1,500 mg/L. The flow experiments in cemented core samples indicated that the resistance factor and residual resistance factor of the HAP solution were 31.8 and 12 when polymer concentration and salinity were 1,500 mg/L, 32,868 mg/L at 85℃ respectively, which is favorable for flooding application. Such factors of partially hydrolyzed polyaerylamide 3530S were merely 3.14 and 1.71, so it could not be applied to polymer flooding in the oilfield with high temperature and high salinity.

Template Effect of Hydrophobically Associating Polymers on the Construction of Cuprous Oxide Micro Structure

To determine the template effect of hydrophobically associating copolymers（HACPs） on the morphology of nano/micro structures, six HACPs were synthesized and used as templates to biomimetically synthesize cuprous oxide（Cu2O）, an important semiconductor. This experiment showed a clear relationship between the associating state of the HACP molecules and the morphology of the Cu2O particles. Cu2O hollow spheres were preferentially prepared when the HACP molecules were in an intramolecular associating state. Furthermore, a Cu2O hexapod was easily obtained when the HACP molecules were in an intermolecular associating state. The morphologies of the Cu2O crystals prepared in the presence of the HACPs also confirmed this result.

井地过渡带对聚合物驱油剂性能影响研究

利用井地过渡带剪切模拟实验装置,以疏水缔合聚合物AP-P4为研究对象,研究不同吸水强度条件下,剪切后聚合物溶液的表观黏度、流变性、阻力和残余阻力系数、微观结构以及水动力学半径的变化情况。结果表明,经井地过渡带剪切后,随着吸水强度的增大,聚合物AP-P4溶液的黏度损失率高达61.4%,建立阻力系数和残余阻力系数的能力降低40.0%以上,但其建立残余阻力系数能力的降低幅度要比建立阻力系数能力的降低幅度小。聚合物溶液的储能模量和损耗模量降低,微观结构被破坏的越严重,水动力学半径越小。

疏水缔合聚合物乳化性能及分相特征

配制了不同的疏水缔合聚合物(HAP),分析了HAP含量、疏水单体含量和油相含量对于聚合物乳化性能的影响,探讨了连续相中疏水缔合结构与油滴的相互作用规律。实验结果表明,HAP乳化时,油滴与连续相中的缔合结构相互作用,形成新的分子链间网络节点,构成了新的三维网络结构,使乳状液增黏。HAP的乳化增黏幅度由连续相与分散相的性质共同决定,其中,HP-1乳状液表观黏度最高增幅为36%。随着HAP中疏水单体含量的增加,乳化增黏幅度逐渐上升;HAP含量一定时,随油相含量增大,HAP乳状液乳化增黏幅度先增大后稳定、稳定性增强,但富集相体积存在最大值。HAP乳化性能及分相特征取决于连续相中的疏水缔合结构与油滴相互作用。

基于油藏化学驱能耗分配原理的理想流度控制型驱油剂研究Ⅰ:聚/表二元复合驱油体系的渗流阻力调控机理及应用

针对驱油剂的深部流度控制能力与近井地带注入性之间的矛盾,提出了理想流度控制型驱油剂应满足低黏度配制/输送、近井地带低吸附量长期稳定注入和低浓度产出液的技术要求,同时,在渗流过程中能够在储层深部不同位置建立多级渗流阻力峰值,并且前缘后驱替相渗流阻力应始终保持在较低水平。基于固/液界面吸附作用与分子间相互作用的协同效应,设计了在渗流过程中具备动态改变体系组成和微观溶液结构,从而改变其渗流阻力特征的疏水缔合聚合物/阴离子型表面活性剂二元体系。相较于HP-1(1500 mg/L),表观黏度相近、组成不同的二元体系HP-1(1500 mg/L)/SDSB(150 mg/L)和HP-1(1500 mg/L)/SDSB(200 mg/L),在段塞注入及其后续水驱过程中可以在多孔介质的中、后部构建数值更高、空间分布更优的动态渗流阻力,说明二元体系具备运移增黏特征和延迟突破特征,其前缘的流度控制能力更强,并且渗流阻力在储层的空间分布更合理,从而延长了段塞整体突破时间,有利于提高波及体积和驱油效率。在相对稠油、强非均质性和水驱含水率为80%的渤海某油田油藏条件下,采用基本相同剂量、相近成本的化学剂工业产品进行的驱油实验表明:二元体系后续水驱突破之前驱油剂段塞渗流阻力的空间动态分布特征是影响驱油效率的关键因素,二元体系(AP-P4(1400 mg/L)/ZX-27(300 mg/L),黏度为6.4 mPa·s)比疏水缔合聚合物AP-P4(1750 mg/L,黏度为62.9 mPa·s)多提高10%的原油采收率。

疏水缔合聚合物强化泡沫室内实验研究

多轮次吞吐稠油储层非均质性加剧,传统氮气泡沫封堵强度难以满足油藏调剖需求。利用疏水缔合聚合物PDR-1对氮气泡沫进行强化,研究了疏水缔合聚合物强化泡沫的机理,评价了强化泡沫的稳泡定性、封堵强度、改善非均质性能和驱油性能。实验结果表明,PDR-1能够与高温起泡剂FCY-2形成混合胶束,具有向气液界面聚集的趋势,同时利用缔合作用大幅提高泡沫液相和气液界面的黏弹性,从而延长了强化泡沫析液半衰期;强化泡沫能够有效封堵大孔道、改善非均质,提高驱油效果,100℃时阻力因子为466.2,综合驱油效率提高29.43百分点;温度越高,PDR-1提升泡沫性能的幅度越小。疏水缔合聚合物强化泡沫体系的研究可为稠油开发的提质增效提供技术支撑。

疏水缔合聚合物高效溶解方法研究进展

疏水缔合聚合物在提高采收率领域中展现出巨大应用潜力,但其疏水基团结构特征使溶解性成为关注焦点。综述了近年来疏水缔合聚合物高效溶解的研究进展,分析了面临的挑战及未来的发展方向。重点介绍了添加化学试剂屏蔽疏水基团的缔合作用,采用筛网切割和胶体研磨等方式增加水与聚合物颗粒的接触面积,以及通过改变聚合物自身溶解性、提高溶液质量浓度或温度、优化搅拌器类型及搅拌方式以增大体系熵变等方法加速疏水缔合聚合物的溶解。化学方法虽然能够快速溶解疏水缔合聚合物且不损害其性能,但其使用成本和环境影响仍需考量。而物理方法尽管经济有效,但可能导致溶液的机械降解和热降解,进而影响增黏性能和驱油效果,同时还需要解决机械设备的运输、能耗以及空间限制问题。因此,研发新型环保溶剂和优化工艺设备对于实现疏水缔合聚合物高效溶解具有重要意义。此外,综合考虑多种高效溶解方法的协同作用,依据实际应用情况进行调整,以期扩大疏水缔合聚合物的规模应用。

增溶改性疏水缔合聚合物的溶解机理及性能

目的疏水缔合聚合物的溶解性制约了在油气开采领域的应用。为了满足油气开采的需要和实现低成本化,研制了疏水缔合聚合物APO,并通过主客体包合技术实现聚合物的增溶改性。方法通过对聚合物结构的设计,提升聚合物的性能,以丙烯酰胺(AM)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)和疏水单体十八烷基聚氧乙烯甲基丙烯酸酯(OEMA)为原料,采用自由基水溶液聚合的方法,合成了疏水缔合聚合物APO,再利用β-环糊精独特的空腔结构进行主客体包合作用来提高其溶解性能。结果25℃下,β-环糊精与聚合物APO的物质的量比为2∶1时,溶解时间由85 min缩短至45 min,聚合物APO在一价及二价盐水中粒径分别降低19.59%和11.50%。结论该聚合物具有好的耐盐性能,β-环糊精能促进聚合物APO的溶解性,减少聚合物用量,实现油气开采的低成本化。

环糊精功能化疏水缔合丙烯酰胺聚合物的制备与性能评价

以十六烷基二甲基烯丙基氯化铵(C_(16)DMAAC)为疏水单体、烯丙基环糊精(A-CD)为环糊精功能化单体,与丙烯酰胺(AM)通过自由基共聚作用制备了环糊精功能化疏水缔合丙烯酰胺聚合物P(AM/A-CD/C_(16)DMAAC)。采用红外光谱和电子扫描电镜对P(AM/A-CD/C_(16)DMAAC)的结构进行表征。并考察了聚合物的水溶性、粘浓性质、特性粘数和粘均分子量。发现聚合物具有良好的空间结构和溶解特性,临界缔合浓度为1600mg/L,粘均分子量达5.5×10^(6)g/mol,聚合物具备作为三次采油的应用潜能。

疏水缔合聚合物压裂液的制备及性能评价

随着非常规油气资源开发的迅速发展,水力压裂技术的压裂液性能成为提高油气产量的关键因素。通过合成阳离子型疏水缔合聚合物PDAH,并将其应用于压裂液体系中,系统评价了其在不同条件下的黏弹性、携砂性和静态滤失性能。研究结果表明,新压裂液体系在室温下剪切速率为0.1s^(-1)时黏度达到503 mPa·s,而在100℃、剪切速率为1 000 s^(-1)时黏度仍保持在262 mPa·s,显示出良好的黏弹性能。携砂性实验表明,该体系在低流速条件下能有效携带和分布支撑剂。静态滤失性实验结果显示,30 min内滤失量稳定在18.7 mL,形成的滤饼厚度约为2.1 mm,表明该压裂液体系具有优秀的滤失控制能力。成本效益分析表明,随着压裂液成本增加,油气产量提升,但成本效益比逐渐降低,需要平衡成本和效益以实现最佳组合。该研究为非常规油气藏水力压裂技术提供了新型压裂液体系,具有重要的研究意义和应用价值。

Viscoelastic rheological property of different types of polymer solutions for enhanced oil recovery

The capability of hydrophobic association polymer(HAPAM) to displace oil is different from that of hydrolyzed polyacrylamide(HPAM) because they have different rheological properties.The viscoelasticity of five polymers was measured using Physica MCR301 rheometer and was compared.The five polymers include three HAPAMs with relative molecular mass of 1 248×104(TypeⅠ),750×104(TypeⅡ),and 571×104(Type Ⅲ) separately and two HPAMs with relative molecular mass of 1 200×104 and 3 800×104 respectively.The experiment results indicate that the viscoelasticity of HAPAM is better than that of HPAM.The storage modulus G' and the loss modulus G″ for HAPAM solutions are also larger than those for HPAM.Comparing the rheological curves of different HAPAM types,it is found that the viscosity of typeⅡ and type Ⅲ is almost same at different shear rates while the viscosity of type I is the lower than that of Types Ⅱ and Ⅲ.The storage modulus G' and the loss modulus G″ for three types of HAPAM were measured in low oscillation frequency range,and the results show that G' is greater than G″ for all three different types of HAPAM,but their loss modulus is almost same,and the G' is in the order of type Ⅱ>type Ⅲ>type I.In addition,the G' and G″ increase with aging time for all three HAPAM solutions were stayed at different days.The viscoelasticity of type Ⅰ reaches the highest value when aging time is 9 d at 45 ℃,but it is 7 d for type Ⅱ and type Ⅲ.The different viscoelasticity properties can be attributed to self-organization supermolecule networks which is formed by hydrophobic association of HAPAM molecular and molecular chain entanglement.

基于长链疏水单体的新型疏水缔合聚合物的分子动力学模拟

为了探究不同疏水单体对聚合物类减阻剂耐盐性能的影响,采用分子动力学模拟方法研究了3种不同的疏水长链型疏水单体与亲水的丙烯酰胺(AM)、丙烯酸(AA)、2-丙烯酰胺基-2-甲基丙磺酸(AMPS)共聚形成的疏水缔合聚合物在盐溶液中的减阻性能和聚集行为。结果表明:3种疏水单体均能提高共聚物与水的相互作用,其中疏水长链由亲水的烷氧基链、烷基链和芳环类疏水基共同组成的疏水单体性能最优异。3种疏水单体均能提高共聚物的回转半径,且链长更长并带有芳环类疏水基的疏水单体使共聚物的流体力学半径更大;此外,聚合物疏水链的疏水缔合有利于促进共聚物通过氢键进行分子间交联,形成聚合物链之间的空间网络结构,增加聚合物链的刚性。减阻性能测试验证了分子动力学模拟结果的正确性。

阳离子型聚合物稠化剂的合成与性能评价

以丙烯酰胺、30%丙烯酰胺/甲叉双丙烯酰胺(29∶1)、甲基丙烯酰氧乙基三甲基氯化铵、十六/十八烷基二甲基烯丙基氯化铵为主要合成单体,聚合引发剂为水溶性2,2-偶氮二(2-甲基丙基脒)二盐酸盐,合成疏水缔合型阳离子聚合物稠化剂(PASM)。对产物进行结构表征及性能测试,结果表明,稠化剂PASM的临界缔合浓度为0.5%,分子量为417.3×104,耐Na+和Ca2+能力强,并且随着矿化度的增加,起初体系的粘度呈现出上升趋势,表现出优异的增稠性能。低浓度使用状态下即可达到较好的防膨效果,悬砂性能优异,经过硫酸铵破胶后无残渣,破胶液不会对地层造成二次伤害,具有广阔的工业化前景。

耐高温低伤害清洁水性稠化剂的制备及性能

以丙烯酰胺、丙烯酸、十八烷基二甲基烯丙基氯化铵和十八烷基甲基丙烯酸酯为原料制备了一种疏水缔合聚合物(AAOS),再使用低分子醇(乙二醇、丙三醇、正丙醇)、表面活性剂(椰子油脂肪酸二乙醇酰胺、十二烷基硫酸钠)、聚乙二醇(PEG)、聚乙烯醇缩丁醛(PVB)和疏水缔合聚合物(AAOS)配制了一种自交联耐高温清洁水性稠化剂(FPM-1)。对FPM-1的形貌、溶解性、表观黏度、耐盐性、流变性进行了测试。结果表明,质量分数为0.30%的FPM-1水溶液能显著增强AAOS聚合物分子间的疏水缔合交联作用,增大聚合物的流体力学体积。FPM-1水溶液为高黏弹性流体,悬砂性能好;质量分数为0.27%的AAOS在水中的溶解时间为7 min,最终表观黏度为90 mPa·s,质量分数为0.60%的FPM-1(具有等效聚合物含量)在水中的溶解时间仅需3 min,且最终表观黏度为165 mPa·s。在90℃、170 s^(-1)条件下剪切1 h后,质量分数为0.27%的AAOS水溶液的表观黏度为51 m Pa·s,质量分数为0.60%的FPM-1水溶液表观黏度为77 m Pa·s;质量分数为1.40%的FPM-1水溶液在180℃、170 s^(-1)条件下剪切1 h,最终表观黏度为53 mPa·s;质量分数为0.60%的FPM-1在5×10^(4)mg/L矿化度盐水中黏度保持率为60%。FPM-1体系能显著提高聚合物的黏度和溶解速度,具有低的表/界面张力,有利于破胶液的返排和回收再利用。FPM-1水溶液具有优异的耐盐、耐高温、耐剪切性能。

双网络结构冻胶堵剂在高温高盐下的性能研究

针对塔河油田高温、高盐等缝洞油藏堵水困难的技术难题,构建了双网络结构的冻胶堵剂体系。以N-(3-二甲胺丙基)甲基丙烯酰胺(DMAPMA)和氯乙酸钠(ClCH2COONa)为原料合成甜菜碱单体TCJ,与单体甲基丙烯酰氧乙基三甲基氯化铵(DMC)和N-(3-二甲氨基丙基)甲基丙烯酰胺(DMAPMA)共聚合成疏水缔合聚合物CDD。采用矿化度为22×10^(4)mg/L的实际地层水,以0.8%(AM/AMPS)聚合物FZ、1.2%酚醛交联剂、0.15%CDD和0.05%特种交联剂CN-10在130℃条件构建互穿双网络结构冻胶CDD-FZ。冻胶性能测试结果表明,双网络冻胶CDD-FZ,仅3 h就能成胶并且成胶强度为H级,最大屈服应力为326.42 Pa,突破压力为88.19MPa/m,30天脱水率1.14%,较传统单层网络结构冻胶具有更高的强度、耐盐性、耐温性和耐稀释性。该研究填补了塔河油田耐温抗盐高强度堵水冻胶的技术的空白,具备较好的实际应用前景。