防气窜固井水泥浆体系的研究

固井后环空气窜是影响油田开发效果的重要因素。本文对目前的丁苯胶乳防窜水泥浆体系和纤维防窜水泥浆体系的防窜机理进行了分析和研究。在此基础上进行了防气窜水泥浆室内研究,对缓凝剂和抗高温材料进行试验和评价,优选出了微膨增韧胶乳防气窜水泥浆配方,满足固井水水泥浆防气窜的性能要求。     

高分散性丁苯胶乳的制备及其对水泥的改性

添加传统丁苯胶乳进行改性,大大提高了水泥的力学性能,但是改性后的水泥材料流动性能差,抗压性能损失较多。为了提高添加丁苯胶乳后水泥的流动性及降低抗压性能损失,本文对丁苯胶乳进行改性,以苯乙烯与聚丁二烯作为核层、带有苯环的对苯乙烯磺酸钠作为壳层,制备出核壳型丁苯（SSBR）胶乳。把新合成的SSBR胶乳加入水泥后,对水泥力学性能进行表征,由于SSBR胶乳中与磺酸根相连的是苯环刚性链,空间位阻效应明显,添加8% SSBR胶乳水泥浆的流变指数增大为0.898,分子链强度大,水泥石的7天抗压强度损失量为2.31%,损失不明显,同时抗折强度提高17%。对SSBR胶乳改性水泥石材料力学性能的作用机理进行探究,结果表明,SSBR胶乳填充作用明显,吸附作用较强,增大水泥浆流动性能,且胶乳粒子可以与Ca²⁺络合,形成三维网状空间立体结构,从而达到增强水泥石力学性能强度,提高水泥石韧性的目的。     

胶乳防窜水泥浆的室内研究与现场应用

对室内合成胶乳进行了粒径测试,室内研究了胶乳加量对水泥浆基本性能的影响,得出胶乳可有效改善水泥浆的失水性能,增强水泥石的韧性,提高水泥环的密封性,有助于提高固井胶结质量,据此优选出了胶乳防窜水泥浆体系,对其静胶凝强度发展、防窜性能等作了相关评价,其胶凝强度过渡很快,防气窜测试无气窜发生,具有良好的防窜效果。并介绍了该胶乳防窜体系在毛坝7井的现场应用。     

一种低黏韧性双防低密度水泥浆的室内性能研究

陆丰油田大位移井储层渗透率低、欠压稳，容易发生气窜，造成固井质量不佳，存在底部高温区域沉降稳定性差、易漏等固井技术难题。针对这些难点，室内筛选3M高强抗压中空玻璃微球来降低水泥浆密度为1.4 g·m^-3的同时可以提高水泥石的抗压强度，选用纤维与胶乳混合作为增韧材料，降低了水泥石的渗透率，有效达到目的层增韧防漏的效果。该增韧材料协同防窜剂CT-1和膨胀剂EXP-1，提高水泥石的胶结强度，具有防漏防窜的作用。由上述主要材料协同其他相关水泥浆添加剂构建了一套具有低黏韧性兼具防漏和防窜性能的低密度水泥浆体系，该低密度水泥浆体系具有良好的流变性，自由液为零，且水泥石上部密度和下部密度差值均小于0.03 g·m^-3，可以看出该韧性水泥浆体系具有优异的沉降稳定性能。低黏韧性双防低密度水泥浆具有良好的力学性能，抗压强度达28 MPa，弹性模量小于7 GPa，抗窜强度大于10 MPa·m^-2，且抗窜效果较普通低密度水泥浆抗窜能力提高了81.2%，说明该水泥浆具有较强封隔能力，可以有效提高固井质量。     

羧基改性丁苯胶乳多元水泥浆的研究

定向井、水平井等复杂结构井由于工艺的特殊性,对水泥浆性能提出了更高的要求。要求套管有更高的抗外挤强度,要增大水泥环二界面胶结强度,降低水泥浆滤液对油气层的污染,提高勘探开发的效果。以往的水泥浆体系都很难同时兼顾这些性能,因此在以往实验的基础上,研制出一种可以应用于复杂结构井固井作业的胶乳多元水泥浆。通过室内实验,优选出羧基改性丁苯胶乳(XSBR)、膨胀剂(BS500)、纤维材料(XW)经过复配制成胶乳多元水泥浆体系,该水泥浆具有零自由水、低失水、微膨胀、防气窜等特点,能够满足复杂结构井固井的要求,在复杂结构井固井中有很好的应用前景。     

含孔片状废旧PET增韧水泥基复合材料的制备及性能评价

废旧塑料高值化利用对促进塑料循环利用具有重要意义。从提高填充材料和基体的啮合强度出发,开发以含孔废旧塑料为增韧材料的增韧水泥基复合材料是废旧塑料高值化利用的有效途径之一。以含孔片状废旧聚对苯二甲酸乙二醇酯(PET)和水泥复合,制备了增韧水泥基复合材料,并考察其抗折强度、冲击性能和拉伸拔脱载荷,分析了其增韧机理。相比未用PET增韧水泥基体,增韧水泥基复合材料的冲击强度由14.6 J/m^2增加到36.7 J/m^2,增加了1.5倍,抗折位移也由0.66 mm陡增至7.4 mm,但抗折强度由7.67 MPa降低到2.85 MPa。上述结果表明,含孔废旧PET塑料片和水泥基体形成的互穿结构起到了传递、分散载荷的作用,使增韧水泥基复合材料由瞬态脆性破坏转变为渐进式韧性破坏,虽然水泥基体的抗折强度降低,但显著延长了水泥基体的弯曲断裂过程,使增韧后的水泥基复合材料具有更强的抵抗碎裂的能力。此外,在研究范围内,水泥基复合材料中废旧PET塑料片材越多,单位塑料片对复合材料的增韧贡献度越大,具有增韧“筷子效应”。     

丁苯胶乳复配乳化沥青防腐涂料制备及性能研究

为了有效控制建筑结构表层腐蚀问题,采用丁苯胶乳复配乳化沥青,同时添加复合型阻燃剂制备防腐涂料,并研究其抗酸碱盐腐蚀、抗剥落性能以及耐火阻燃性能。结果表明,选用7∶3的丁苯胶乳复配乳化沥青,固化剂用量16%,复合型阻燃剂用量5%,分散剂用量1%,成膜助剂用量3%,涂层厚度为100μm时,制备的防腐材料具有优良的耐水、耐盐、耐酸和耐碱性能,同时具备一定的耐火阻燃性能,但抗冻融循环性能较差。     

养护条件与聚灰比对增韧水性环氧水泥基涂层性能的影响及其机理

研究了养护条件和聚灰比对掺加水性聚氨酯增韧环氧水泥基涂层性能的影响。结果表明:当聚灰比为15%,经历自然养护7 d后80℃干养4 h的增韧环氧水泥基涂层钢筋电极,在3.5%NaCl溶液中浸泡28 d后腐蚀电流密度保持在0.15μA/cm~2以下,表明涂层耐腐蚀性能良好;按照标准试验方法测试涂层柔韧性、抗剥离、抗冲击及耐酸碱盐性能优异。扫描电镜结果表明环氧树脂包裹水泥水化产物形成了聚合物膜。应用电子能谱仪观察元素变化,分析了环氧交联度对水泥基材料性能影响的作用机理。     

油井水泥专用丁苯胶乳的实验评价

针对传统丁苯胶乳在油井水泥浆中适用性能差的问题,采用种子乳液聚合方法合成了一种油井水泥专用丁苯胶乳,并对其进行了微观结构和应用性能评价。该丁苯胶乳物理性能、红外及热失重分析结果表明：该丁苯胶乳乳液稳定性好,高温下分子结构稳定。丁苯胶乳水泥浆的应用性能结果和微观结构分析表明：该丁苯胶乳水泥浆API失水可控制在50 mL内,耐盐性能好,可解决传统胶乳水泥浆稠化实验"鼓包"、"包心"等问题;加有该丁苯胶乳的水泥浆早期强度发展快,胶凝强度过渡时间短;丁苯胶乳能细化水泥浆的孔径结构,提高水泥浆的胶结强度和形变能力,并且其水泥石的柔韧性比原浆水泥石提高了30%;此外,能够满足深井、超深井和气井等复杂井的固井作业要求。     

羧基丁苯胶乳水泥浆的制备及性能研究

羧基丁苯胶乳是一种稳定且含有表面活性剂水溶液的聚合物粒子分散体。作为水泥的添加剂,用于改进水泥砂浆或混凝土的性能,它既要求改性后的水泥材料抗压强度、抗张强度、耐水、耐候性能好,同时又要求胶乳的粘结力强,并与水泥易掺混,在常温下可快速成膜。因此在研究过程中不仅要考虑到胶乳乳液聚合过程,还要考虑到许多影响胶乳性能和最终用途的因素,从而使改性的水泥砂浆可适用于不同的领域。本文综合运用表面活性剂技术、外加剂复配技术以及水泥石物相微观分析测试技术,研究了羧基丁苯胶乳对不同体系的水泥石力学性能的影响。实验结果表明,在羧基丁苯胶乳适当加量下的,使油井水泥浆流变性、强度、稠化时间、和降失水性能都有很大的改善,有助于水泥环在后续施工过程中维持长期有效层间封隔。     

丁苯橡胶对水泥水化过程及水泥石微观结构的影响

用多种实验手段研究了在普通硅酸盐水泥中掺入丁苯橡胶乳液对水泥水化过程的影响，并用扫描电镜分析了掺入丁苯橡胶后水泥石微观结构形态的改变，从而探讨了丁苯橡胶改善水泥石物理力学性能的机理。     

Influence of PP fiber and SBR latex on the mechanical properties of crumb rubber mortar

This article presents a new kind of rubber mortar modified by polypropylene fiber (PP fiber) and styrene‐butadiene rubber latex (SBR latex). The mechanical properties of this crumb rubber mortar were investigated in the research, including the compressive strength, flexural strength, flexural toughness, and flexural elasticity modulus. The test results showed that the flexural toughness index of the rubber mortar was seen to enhance by about 50–100% with the addition of PP fiber and SBR polymer latex. Due to the addition of PP fiber and SBR latex, the flexural elastic modulus of rubber mortar could further reduce by 4–27%. The three‐phase composite dispersion model of this rubber mortar was put forward. Furthermore, it was observed from scanning electron micrograph that the interfacial transition zone between the rubber particles and cement paste was enhanced by the SBR latex, and the interleaving of polymer films and rubber particles strengthen the flexibility and toughness of the mortar. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40591.     

Effects of carboxylated styrene-butadiene latex nanoparticles on channeling leakage and pore structure of oil well cement

The exploitation efficiency of oil and gas resources depends on the cementing quality. In cementing engineering, interlayer migration occurs in the underground gas layer with cement hole as the main channel, which seriously threatens the sealing integrity of cement casing and leads to the failure of cementing operation. To improve the gas migration control ability of oil well cement (OWC), two carboxylated styrene-butadiene latex nanomaterials styrene butadiene latex containing itaconic acid and sodium p-styrene sulfonate (SBSI) and styrene-butadiene latex containing methacrylic acid and sodium p-styrene sulfonate (SBSM) were synthesized. The effects of SBSI and SBSM with different carboxyl structures on the gas migration control ability and pore structure of cement were investigated. The results show that the latex is densely packed on the cement matrix through the dissociation and adsorption behavior of carboxyl groups, and the smaller particle size and lower adsorption are more conducive to the formation of the film. The introduction of latex effectively shortened the transition time of cement gel state and significantly reduced the permeability of interlayer material migration. Compared with OWC, the transition time of cement containing SBSI and SBSM latex (SBSI/OWC and SBSM/OWC) decreased from 28 to 18 and 17 min, respectively, and the filter loss decreased from 60 to 40 and 36 mL, respectively. The isolation effect of the latex film on the interlayer gas and the provision of mechanical support have greatly improved the gas migration control ability of the cement and ensured the cementing quality. In addition, the refinement of cement pore structure caused by latex brings better rheological and mechanical properties to cement. This study clarified the change of latex in the gel transition stage of OWC from liquid to solid and revealed the mechanism of latex on the internal structure change of cement. It broadens the application range of latex nanomaterials in the field of OWC and provides a new possibility for the use of OWC in high temperature and high salt environment.     

Retardation effect of styrene-acrylate copolymer latexes on cement hydration

Interactions between styrene-acrylate latexes and cement are investigated with emphasis of the charge properties of the polymer particles by means of calorimetry, adsorption measurement, and confocal laser scanning microscope. Three latexes with varied surface charges of polymer particles were prepared by respectively using methacrylic acid (MAA), sodium styrene sulfonate (SSS) and methyl poly(ethylene glycol) methacrylate (MPEGMA) as water soluble monomers during synthesis. It is found that the polymer latexes retard cement hydration in two manners, namely the delaying effect represented by a delayed hydration peak and the slowing down effect characterized by a reduced main hydration peak during the acceleration period. The delaying effect is closely related to the concentration of carboxylic groups existing in the latex, while the depression effect of hydration rate is majorly caused by the adsorption of polymer particles on surface of cement grains and proportional to the total charge density of polymer particles.     

Hypothesis for Reinforcement of Portland Cement by Polymer Latexes

Vinylidene chloride and styrene-butadiene copolymer latexes are used commercially to reinforce portland cements. Although the technology is well developed, the mechanism of reinforcement is not well understood. A hypothesis is proposed to explain this reinforcement, i.e. (1) latex substitutes for all or part of the water to give the same fluidity at a lower water/cement ratio; (2) latex particles coalesce around each unhydrated (or slightly hydrated) cement grain and aggregate particle to form an interpenetrating network of polymer throughout the structure; (3) microcracks form throughout the structure to relieve the strain introduced by the shrinkage of the portland cement that occurs when the relative humidity falls below 100%; and (4) a propagating microcrack intersects the interpenetrating polymer network to form microfibers spanning the microcrack, sometimes so effectively that propagation is halted, but always so that the microcrack is held together. This hypothesis was supported by scanning electron microscopy of latex-modified cement specimens, as well as by other experiments. More work is needed to determine how each part of the hypothesis contributes to the physical properties of latex-modified cement.     

一种新型吸水性胶棉的制备及应用

以聚乙烯醇、淀粉和甲醛为主要原料,加入少量的羧基丁苯橡胶乳剂,通过简单的工艺,制成一种高强度、高弹性、高吸水性、耐酸、耐碱的新型吸水性胶棉。最佳条件为:m(PVA)∶m(淀粉)∶m(甲醛)∶m(丁苯胶乳)=5∶3∶3.4∶1。此种胶棉可用来制作环保型白板书写教具的板擦。     

Microstructure of Hardened Cement Paste—A New Interpretation

Morphological features of hydrated portland cement paste exhibited on carefully polished surfaces have been critically examined using backscatter mode scanning electron microscopy. A new interpretation and classification of such features is proposed. The microstructure is seen to consist of distinct grains of the order of 10 μm and larger ("phenograins") set in a cellular groundmass of smaller particles and pores. Most of the phenograins are dense pseudomorphs of the larger cement grains, but some are large calcium hydroxide crystals, and in some cements a few may represent inert filler grains added to the cement. The phenograins that are pseudomorphs of cement particles may be solid, gapped, or hollow; and, at a given age, various stages of hydration are represented in different grains. While many pseudomorph phenograins consist of a simple core of unhydrated material surrounded by a uniform shell of hydration product, more complex and irregular structures are also found. Relationships between these features and earlier classifications of cement hydration product particles are discussed, and implications with respect to difficulties in image analysis of hardened cement paste are examined.     

On the properties of freshly made Portland cement paste. Part I. Origins of the colloidal behaviour of cement paste

A freshly made Portland cement paste is a very unusual fluid. It behaves like a colloidal suspension, although cement particles are much coarser than conventional colloid size. The origins of this colloidal behaviour of a cement paste have been traced to high density and high viscosity of the paste itself. Its high density and viscosity hinder the sedimentation of cement grains and allow for the colloid behaviour to develop.     

Rheology of latex-modified grouts

The rheology of grouts containing latex was investigated. The two latex additives used were carboxylated styrene-butadiene and acrylic. The influences of superplasticizer, fly ash, and blast furnace slag on the rheology of latex-modified grouts were addressed. Shear stress-shear rate curves were determined for a variety of mix proportions. The time-dependent behaviour of selected grouts was also studied. It was determined that the yield stress and apparent viscosity are influenced by latex content and that the grouts are shear thinning at low water/cement ratios. Latex imparts stability and thixotropy in grouts. Partial replacement of cement with either fly ash or slag diminishes the effect of latex on rheology.