HJH-1型高温油井水泥缓凝剂的合成及其性能评价

以MA、AMPS、AM为原料合成一种高温油井水泥缓凝剂HJH-1,通过正交实验确定最佳合成条件为:m(MA)∶m(AMPS)∶m(AM)=21∶9∶8、引发剂加量8%(以单体总质量计)、反应温度90℃和反应时间6 h,并对其应用性能进行评价。结果表明,HJH-1型缓凝剂在140℃的高温环境下仍具有很好的缓凝效果,4%加量时稠化时间为300 min,初始稠度低于30 Bc,稠化线形良好,直角稠化时间小于20 min;稠化时间可调性好,温度和加量敏感性低,综合性能满足固井施工安全要求;此外,将低场核磁共振分析技术应用于塑性水泥浆的研究,测试水泥浆体初凝前的横向弛豫时间T2分布,进一步分析了在初始水化阶段水泥浆体中水的存在状态及该缓凝剂对水泥浆初始阶段水化过程的影响。     

WJ-1型缓凝剂对水泥浆早期水化过程的影响

针对油井施工高温环境下水泥浆缓凝技术的需要,以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)、马来酸酐(MA)和丙烯酰胺(AM)为单体合成了三元共聚物W J-1型缓凝剂.经正交实验得最佳合成条件:单体质量比AMPS:MA:AM =21:9:8、反应温度90℃、反应时间5h、∞(引发剂)=4％(占所有单体质量比).高温高压(120℃、73.9MPa)稠化时间表明其具有良好的缓凝性能.用低场核磁对比研究了纯水泥浆G和掺加缓凝剂的水泥浆GR的横向弛豫时间在不同时间点的T2值分布情况和T2总信号量随水化时间的变化.结果表明:在初始水化阶段的150min内,对比弛豫峰的变化发现,水泥浆GR的弛豫峰峰形和峰顶位置均无明显变化,水泥浆G的弛豫峰峰形变窄且峰顶位置向短弛豫方向偏移;随水化时间的进行,T2总信号量不断减小,反映了浆体中自由水转变为化学结合水的过程.     

改性纳米SiO2@AEPM聚合物耐温缓凝剂制备及性能评价

本文利用纳米材料自身的耐温性能，采用溶胶-溶液法在纳米SiO₂表面接枝一定的疏水聚合物单体AEPM，得到一种耐温缓凝剂SiO₂@AEPM，通过红外光谱、粒径分析及热重分析对其结构进行表征。并对SiO₂@AEPM加入后的水泥浆体系稠化性能及水泥石抗压强度进行评价，实验结果表明，SiO₂@AEPM缓凝剂的温度适用范围为110～200℃，200℃时SiO₂@AEPM缓凝剂体系的稠化时间为254min，在高温条件下，SiO₂@AEPM缓凝剂具有良好的缓凝性能。浓度为0.3%时，90℃养护168h的水泥石抗压强度达到48.5MPa,SiO₂@AEPM缓凝剂在高温条件下能够起到在延长水泥浆体系稠化时间的同时对水泥石强度无影响，可适用于温度大于100℃的大温差、超深井固井作业。     

油井水泥多功能高温缓凝剂的研究

为满足深井固井对油井水泥缓凝剂抗高温性能的需要,研制了多功能高温缓凝剂（MP）,并对MP的高温缓凝性能、降滤失性能进行了室内评价。结果表明：MP具有优良的抗温缓凝效果,稠化时间可调;稠化时间的重现性好;还能有效地降低水泥浆的失水量。此外,使用量热仪研究了MP对水泥浆水化反应速度的影响,发现MP使水泥浆的初始水化放热速率减小,水化诱导期延长,随着高温缓凝剂MP掺量的增加,水泥水化最高放热峰出现的时间按比例延长,缓凝性能线性关系良好。     

减水剂对水泥浆体横向弛豫时间曲线的影响

研究了初凝前的水泥浆体在质子共振频率23 MHz下的横向弛豫时间(72)分布,主要对纯水泥浆体和掺减水剂的水泥浆体在水化5,30,60,90,120min时的弛豫时间进行了测试和分析.结果表明:测试到的水泥浆体的弛豫时间分布曲线出现了3个T2弛豫峰;第1弛豫峰处于0.01 ms至0.20ms之间,与水泥浆体中的物理结合...     

钢壳沉管自密实混凝土工作性能评价方法的对比试验研究

自密实混凝土目前尚无统一的工作性能评价方法。通过在室内开展500~850 mm扩展度范围的自密实混凝土工作性能指标的对比试验,从填充性、间隙通过性和抗离析性能三个方面对自密实混凝土的性能评价方法进行了讨论。结果表明:采用坍落扩展度U_SF、扩展时间T₅₀₀、L型仪测试通过率H₂/H₁和视觉稳定性指数A_VSI的综合评价指标可对自密实混凝土的工作性能进行较好的表征;U_SF和T₅₀₀对自密实混凝土的填充性可以进行比较好的评价;L型仪或J环试验对自密实混凝土的间隙通过性可以进行较好的评价;对现场混凝土的稳定性可先采用视觉稳定性试验(VSI)初步评价,需要定量评价时,可采用离析率筛析试验(GTM筛析法);对侧墙等竖向构件混凝土的抗离析性评价,除了采用GTM筛析法之外,必要时还需增加压力泌水试验。     

缓凝剂对水泥浆中自由水状态演变的影响

用低场核磁共振技术考察了HN-1型缓凝剂对水泥浆体中可蒸发水的横向弛豫时间(T2)及状态演变过程的影响。结果表明:在初始水化阶段的150 min内,水泥浆GR(添加缓凝剂HN-1的水泥净浆)的弛豫峰峰形和峰顶位置均无明显变化,水泥浆G(纯水泥净浆)的弛豫峰峰形变窄且峰顶位置从2.15 ms迁移至0.95 ms,说明缓凝剂HN-1主要通过改变水泥浆体中不同状态水的存留时间来改变其水化进程。随养护时间的延长,硬化水泥石W0.44和WR0.5中可挥发水弛豫峰分布范围分别从0.11~4.75 ms变为0.08~0.58 ms、0.24~4.23 ms变为0.11~2.35 ms,总体趋向于短弛豫时间,表明水泥石中毛细水逐渐向凝胶水和物理结合水转化,水泥石养护龄期延长至25 d时,其内部凝胶结构水含量超过90%。利用XRD考察了缓凝剂对水泥浆水化产物的影响,结果表明:缓凝剂只改变水泥浆水化过程,对最终水化产物晶型及晶型结构不存在任何影响。     

一步法合成α-MnO2/β-MnO2催化剂及其对甲苯催化氧化的性能研究

采用水热法在不同pH条件下制备了一系列MnO₂基催化剂,通过XRD、SEM、N₂吸脱附等手段对其进行了表征,并评价了它们对甲苯催化氧化反应的催化活性。表征结果表明,不同的pH本质上改变了s反应溶液的初始H⁺浓度,从而影响了所得样品的结晶环境,并赋予它们不同的晶相。甲苯的催化氧化评价结果表明,催化剂的催化性能与α-MnO₂的含量密切相关。当pH=11时所得到的MnO₂-11催化剂,具有最大的比表面积和最多的缺陷结构,使其具有最佳的催化活性（T₅₀=245℃和T₉₀=256℃）和优异的循环稳定性。     

一步法合成α-MnO2/β-MnO2催化剂及其对甲苯催化氧化的性能研究

采用水热法在不同pH条件下制备了一系列MnO₂基催化剂,通过XRD、SEM、N₂吸脱附等手段对其进行了表征,并评价了它们对甲苯催化氧化反应的催化活性。表征结果表明,不同的pH本质上改变了s反应溶液的初始H⁺浓度,从而影响了所得样品的结晶环境,并赋予它们不同的晶相。甲苯的催化氧化评价结果表明,催化剂的催化性能与α-MnO₂的含量密切相关。当pH=11时所得到的MnO₂-11催化剂,具有最大的比表面积和最多的缺陷结构,使其具有最佳的催化活性（T₅₀=245℃和T₉₀=256℃）和优异的循环稳定性。     

Ce掺杂对Ru/TiO2催化氯苯性能的影响

采用等体积浸渍法制备了单贵金属Ru/TiO₂和双金属Ru-Ce/TiO₂系列催化剂，测试了其对氯苯的催化活性，并通过N₂吸脱附、扫描电镜(SEM)、程序升温还原(H₂-TPR)进行表征，旨在考察稀土元素Ce掺杂对Ru/TiO₂催化氯苯性能的影响。结果表明，Ce的引入可使其在降低贵金属含量的基础上仍保持高的催化效率，且极大地提高了低温催化活性。0.4%Ru-1.0%Ce/TiO₂与0.4%Ru/TiO₂相比，其T₁₀和T₉₀分别降低了50℃和60℃。H₂-TPR表明引入Ce为催化剂提供了更多的表面氧空位，形成Ru-O-Ce增强了其氧化还原能力。掺杂Ce未改变Ru/TiO₂催化剂的结构形貌，仍保持介孔结构，但若负载量过多，会堵塞部分孔道，阻碍污染物吸附及反应，降低催化性能。     

Studies of Physical State of Water in Maize from Northeast China (cv. Huangmo 417) During Drying at Subzero Temperatures

In northeastern provinces of China, maize is one of the main sources of income in agriculture. After harvest, the grain is kept under subzero conditions for 3-4 months. Studies have been undertaken to assess the feasibility of drying at subzero temperatures during storage. Using a combination of NMR and MRI enabled a better understanding of physical states of water in the cv. Huangmo 417 during drying at subzero temperatures. The studies showed two water components with different relaxation times (long and short T₁) that were found when temperature was lowered from +25 to -30°C. T₁ was a minimum when the temperature was reduced to -20°C. T₂ was found to be much shorter than T₁. This was an indication that water mobility was decreasing at the same time as the temperature. The results from MRI revealed the location of frozen water in different areas of the maize kernel during subzero drying. This approach to characterizing the states of water in maize under subzero conditions will assist in devising drying strategies for northeastern China.     

1H NMR Imaging Study of Molecular Mobility in Silica-Filled, TBBS-Sulfur Vulcanized Cis-Polyisoprene

The interactions of silica in zinc-activated, sulfur-vulcanized cis-1.4 polyisoprene were characterized at the 75% cure state using ¹H NMR imaging spectroscopy. Variables examined included silica loading, mixing conditions, and presence of additives, including a coupling agent and polyethylene glycol. Rheometer curves indicated a decrease in cure rate and cure state as silica was increased. ¹H NMR imaging showed an increase in the T₂ relaxation times, and a decrease in the proton spin density N(H) as the filler load increases. Mixing conditions did not affect the cure rate, cure state, or the average T₂ relaxation time; however, the distribution of relaxation times broadened with poor mixing. The presence of a coupling agent increased the cure rate and cure state, as well as decreased the T₂ relaxation times as compared with samples with the same silica level, but without coupling agent. Polyethylene glycol (PEG) had slightly higher average T₂ relaxation times, and a slightly broader distribution as compared with the sample without PEG added.     

缓凝剂对补偿收缩胶凝体系水化放热的影响

采用等温量热法,研究了酒石酸和硼酸这2种缓凝剂对掺氧化钙型膨胀剂与氧化钙-硫铝酸钙复合型膨胀剂的水泥净浆的诱导期结束时间、主放热峰出现时间及其最大放热速率、不同时间累计放热量等方面的影响.结果表明:与掺膨胀剂水泥净浆相比,缓凝剂均明显推迟补偿收缩胶凝材料体系的诱导期结束时间和主放热峰出现时间,减少最大放热速率和24 h内累计水化热,72 h总水化热略低.对氧化钙型膨胀剂水泥体系,硼酸比酒石酸缓凝效果好.     

NMR diffusion and relaxation studies during cement hydration—A non-destructive approach for clarification of the mechanism of internal post curing of cementitious materials

Internal post-curing of hardening cement pastes by addition of alginate spheres, which contain 98% of water, is studied by non-destructive ¹H NMR measurements of transverse relaxation time and self-diffusion. The onset and amount of water transition from the alginate gel used as additive with temporary delayed release of water to cement pastes was observed continuously during the dormant and accelerated period of cement hydration. During hydration, the water transition from the alginate into the cement matrix as well as the development of pore size is monitored quantitatively by studying the time dependence of characteristic peaks in the transverse relaxation time distribution. Comparison between samples without and with internal post curing shows that the addition of alginate gel does not influence the pore size in the micropore region. NMR diffusion studies demonstrate that the physically bound pore water has sufficient mobility to ensure homogeneous distribution of water from the alginate source into the surrounding cement matrix during the dormant and accelerated period.     

NMR studies of hydrating cement: A spin-spin relaxation study of the early hydration stage

The early stages of cement hydration were investigated by proton spin-spin relaxation time (T_c) measurements because these experiments can be performed much faster (in several seconds) than the characteristic time for a change in hydration evolution. In addition, comparing the free induction decays of nuclear magnetization and its spin echoes allows the separation of solid-like and liquid-like proton groups. The values of T₂ and the associated magnetization fractions were monitored for cement pastes with different water/cement ratios in the first 20 hours of hydration.

Results show that already at the time of the first measurement, i.e. six minutes after mixing dry white cement powder with water, a quasi steady state is reached with protons distributed in three groups: loosely bound water (in the gel coatings and interstital spaces between coated clinker grains with T₂ of several ms), tightly bound water (T₂ 100μs) and water/hydroxyl protons in crystalline structure (T₂ 10 μs). The values of T₂ and their associated magnetizations are fairly constant during the first several hours with the solid-like components only slowly growing at the expense of the liquid one. The fraction of the loosely bound water as well as the absolute value of its T₂ increases with increasing w/c ratio. These data indicate that although nothing vigorous is happening in the dormant period of cement hydration there is a continuous growth of the solid matrix.     

Preparation,characterization, and retarding mechanism of high temperature resistant amphoteric ion polymer oil well cement retarder Poly-AAMD for HTHP application

The amphoteric ion polymer cement retarder Poly-AAMD was synthesized by aqueous solution polymerization, the chemical structure, molecular weight, and thermal stability was studied. As a result, the M_n and M_w are 1.3 × 10⁴ and 4.7 × 10⁴ g/mol, respectively, and the initial decomposition temperature is 260°C. Then, the effects of retarder Poly-AAMD on the application performance of cement slurry, such as settlement stability, thickening time, compressive strength, and rheological properties, were investigated. Especially, the thickening time of cement slurry with 1.2 and 1.5 wt% retarder Poly-AAMD is 312 and 316 min at 220°C, the compressive strength is larger than 14 MPa at 24 h. Compared to conventional retarders, the temperature resistance has been improved to 220°C. Simultaneously, the initial hydration process of cement slurry was studied by low field NMR based on the T₂ value. Moreover, the hydration products of cement slurry with retarder Poly-AAMD were analyzed depends on the qualitative and quantitative analysis methods, the type and content of hydration products were confirmed by the methods of X-ray diffraction analysis (XRD), scanning electron microscope (SEM), thermogravimetric analysis (TG), and differential thermal analysis (DTG). Finally, the retarding mechanism of retarder Poly-AAMD was further studied depends on the results of adsorption amount and Zeta potential.     

烧结烟气脱硫灰作水泥缓凝剂的试验研究

以天然石膏作对比,研究了烧结烟气脱硫灰作为缓凝剂对水泥性能的影响。试验表明,烧结烟气脱硫灰用作水泥缓凝剂是可行的,但是脱硫灰在延长水泥凝结时间,提高水泥的力学性能方面的作用效果不如天然石膏。试验中确定脱硫灰的最佳掺加量为7%。脱硫灰作水泥缓凝剂时,起缓凝作用的水化产物可能是3CaO.Al2O3.CaSO3.11H2O,而非AFt、AFm。     

硼砂/三乙醇胺复合缓凝剂对磷酸钾镁水泥水化硬化性能的影响

磷酸钾镁水泥(MKPC)的速凝特性限制了其在更多工程领域的应用发展，有效延长凝结时间是其工程化应用的关键技术之一。本研究使用硼砂/三乙醇胺复合缓凝剂，深入研究了其对磷酸钾镁水泥凝结时间、抗压强度、物相组成、微观形貌、孔结构和水化放热等特性的影响，并探讨了缓凝机理。结果表明：在保障7 d抗压强度大于20 MPa条件下，复合缓凝剂的使用，可实现26～100 min的凝结时间调控；三乙醇胺分子包覆MgO颗粒，发挥阻水作用，从而显著降低水化反应的标准水化放热速率与标准水化放热量，达到缓凝效果；试样中K-鸟粪石含量的减少与大于10 nm孔隙体积的增加是削弱抗压强度的主要原因。     

The influence of VTES on the hydration process of C3S

This paper investigated the hydration process of tricalcium silicate (C₃S) in which a small amount of vinyltriethoxysilane (VTES) was added by using the techniques of ¹H NMR, ²⁹Si MAS-NMR and XRD. In comparison with the hydration process of C₃S without adding any additives, not only the average molecular weight of hydrated calcium silicate in C₃S paste, but also the ordering of the silicon nuclei in it increased. This indicates that the VTES has joined effectively into the real hydration process of C₃S. These results imply some possible reasons why the intrinsic properties of low porosity hardened cement paste (HCP) in which a small amount of VTES was added could be improved. Besides, it has been found that in early stage hydration of C₃S with or without VTES, Ca(OH)₂ crystal in the paste appears earlier than Q₁ which shows that in the first several hours of hydration, there only exists Si(OH)₄ and other basic salts and no dimer and polymer of silicate anion when Ca(OH)₂ crystal begins to form.