MgO作矿化剂对多孔轻质陶粒支撑剂结构和性能的影响

以山西忻州高铝煤矸石为主要原料,碳粉为造孔剂,采用常压烧结法,制备出了密度较低的石油压裂支撑剂,但造孔作用使得支撑剂的强度变低.为了能够在降低支撑剂密度的同时保证强度,添加MgO作矿化剂来改善支撑剂的强度.通过分析检测表明:引入适量的氧化镁做矿化剂,可促进液相烧结,对抑制莫来石晶粒长大有利,改善了支撑剂强度.当碳粉添加量为10wt％,氧化镁添加量为2wt％,烧结温度为1350℃时,获得的支撑剂性样品能最佳,体密度仅为1.35 g/cm3,视密度为2.41 g/cm3,35 MPa下破碎率为4.58％.     

低密度高强度覆膜陶粒支撑剂的制备与性能研究

以工业废料粉煤灰为主要原料,以MnO2和钾长石作为助熔剂,采用传统造粒方法和高温烧结技术,结合树脂覆膜的方法,制备了低密度高强度的树脂覆膜陶粒支撑剂.研究了MnO2的加入量、烧结温度、保温时间对陶粒支撑剂性能的影响规律,利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)对陶粒支撑剂中主要晶相和显微结构进行了分析.研究结果表明:当加入2wt％的MnO2时,显著降低了支撑剂的烧成温度,促进烧结提高了致密度.通过树脂覆膜大幅提高了支撑剂的性能,覆膜后,其52 MPa破碎率最多下降了87.3％,视密度也显著下降.     

白云石对焦宝石陶粒晶粒发育及性能的影响

以陶粒的新原料-焦宝石为主要原料,白云石为熔剂性辅料利用陶瓷烧结工艺成功制备了粒径425~850 μm满足35 MPa闭合压力下使用的支撑剂.重点研究了助熔剂白云石的不同添加量对焦宝石陶粒支撑剂晶粒发育及性能的影响.利用SEM和XRD分别对含有不同添加量的白云石的陶粒支撑剂进行了显微形貌和物相结构的分析,并多次测试了陶粒支撑剂的体密、视密和破碎率,结果揭示了白云石的添加有助于促进棒状莫来石晶粒的发育,同时在保证破碎率低于9%的前提下具有降低陶粒支撑剂体密/视密的作用.     

烧结温度对添加镁渣制备陶粒支撑剂性能的影响

采用山西阳泉铝矾土和煤矸石为主要原料,工业废弃物镁渣为添加剂,在1180～1350℃下烧结制备陶粒支撑剂.对比分析各温度下陶粒体积密度,视密度和破碎率的变化趋势,利用XRD和SEM对陶粒的物相及微观形貌进行了表征.探讨了烧结温度对添加镁渣制备陶粒支撑剂性能的影响,同时明确了最好性能陶粒支撑剂对应的最佳烧结温度.结果表明:烧结温度为1250℃时,陶粒支撑剂的体积密度为1.39 g/cm3,视密度为2.84 g/cm3,48 MPa闭合压力下破碎率为6.87％,52 MPa闭合压力下破碎率为8.64％.在该温度下,陶粒的性能较好,烧结致密度很高.     

高强度低密度陶粒支撑剂的研究

以铝矾土为原料,白云石为辅料,添加一定量的复合添加剂,经粉磨、成球和烧成,制备了性能优良的高强度低密度陶粒支撑剂,讨论了复合添加剂掺量及烧成温度对陶粒支撑剂材料性能的影响。结果表明,当白云石掺量为2%,复合添加剂的掺量为6%,烧成温度在1330℃时,制备出的陶粒支撑剂的视密度为2.61g/cm-3,体积密度为1.55g/cm-3,52MPa闭合压力下的破碎率为6.70%。     

烧结温度对煤层气井用陶粒支撑剂的影响研究

本文以阳泉铝矾土和煤矸石为原料,长石为烧结助剂,制备了适用于煤层气水力压裂开采的陶粒支撑剂.利用SEM和XRD,表征了不同温度下烧结的陶粒支撑剂的显微结构及物相组成;研究了烧结温度对陶粒支撑剂材料的抗破碎率、密度的影响.结果表明:样品结晶相为莫来石,刚玉和方石英,并随着温度升高,莫来石相含量逐渐增多,且结晶度也越来越好,在1450℃时,二次莫来石仍未转化完成;随着烧结温度的升高,样品密度与呈先上升后下降的趋势,破碎率呈现先降低后升高的趋势.1300℃烧结下的样品性能最好,体积密度为1.40 g/cm3,35 MPa下破碎率为7.06％.     

掺锰超轻支撑剂的制备及性能研究

在保证支撑剂高强度的条件下，尽可能降低支撑剂的视密度是页岩气清水压裂技术开发的关键。本工作以低品位铝矾土、微米SiO2为主原料，水玻璃、纳米SiO2、氧化锰为辅料，用等离子动态烧结和后期高温烧结法制备方法制备超轻支撑剂，探讨了不同氧化锰掺杂量和不同烧结时间对其物相成分、体积密度、视密度和承压69 MPa下破碎率的影响。并基于经典PKN压裂模型模拟超轻支撑剂在裂缝中沉降与运移规律进行研究。结果表明，成功制备了视密度为1.639 g/cm3，在69 MPa下破碎率8.91%的超轻支撑剂，其最佳氧化锰掺杂量为7.5wt%，最佳烧结温度和烧结时间为950℃和2 h。超轻支撑剂比常规支撑剂在水平方向上运移了更长的距离，支撑剂在裂缝内部的分布也相对更均匀，可以满足中深油井的清水压裂要求。     

V2O5掺杂对莫来石晶须增强型陶粒支撑剂的性能影响

以高岭石质煤矸石为主要原料,V2O5为添加剂,于1400 ℃下制备了莫来石晶须增强的陶粒支撑剂,讨论了V2O5促进莫来石晶须生长机制及其添加量对支撑剂样品性能的影响.结果表明:随着V2O5的加入,支撑剂样品的主晶相莫来石逐渐生长形成莫来石晶须;当V2O5添加量为1wt％时,试样的性能最佳;体积密度1.25 g/cm3,视密度2.69 g/cm3,52 MPa闭合压力下的破碎率5.18％.     

基于煤层气井用陶粒支撑剂的制备

以煤矸石和铝矾土为主要原料,采用50∶50和60∶40质量配比,再添加2wt％长石添加剂,在不同温度烧结制备了煤层气井用的20/40目经济型陶粒支撑剂.通过X射线衍射(XRD)和扫描电子显微镜(SEM)对陶粒的物相组成和显微形貌进行表征.实验结果表明:所制备的陶粒的视密度均低于3.0 g,/cm3,体积密度低于1.5 g/cm3,属于低密度范畴;当煤矸石与铝矾土配比为50∶50时,烧结温度在1400 ～ 1500℃制备的支撑剂,在35 MPa闭合压力下的破碎率均低于9％的行业标准(SY/T 5108-2014).     

添加陶粒砂废料对制备支撑剂的影响

陶粒支撑剂废料,混合铝矾土粉、黏土为原料,采取逐步添加的方法研究了废料的加入量对支撑剂性能的影响。结果表明,其半成品体积密度增高,同一烧结温度下,成品体积密度也增高,破碎率增大,强度降低。     

Sintering mechanism of high-intensity and low-density ceramic proppants prepared by recycling of waste ceramic sands

Waste ceramic sands were effectively used to prepare the high-intensity and low-density ceramic proppants, realising the recycling of the waste ceramic sands. The technology involved the pelletising in an intensive mixer, in which the waste ceramic sands and other starting materials were added, and followed by heat-treatment under different sintering conditions. The sintering temperature, holding time and heating rate were optimised by investigating the crystalline phase, microstructure, density and breakage ratio of the obtained proppants. The results showed that the proppants sintered at 1260°C for 2?h with a heating rate of 5°C?min^–1 under air atmosphere exhibited high crush resistance and low density, with the breakage ratio of 8.5% under 52?MPa closure pressure and bulk density of 1.65?g?cm^–3. The proppants prepared by bauxite, waste ceramic sands and sintering aids are promising candidates as high-intensity and low-density fracturing proppants in future applications.     

Effects of sintering temperature on microstructure,properties, and crushing behavior of ceramic proppants

Ceramic proppants with excellent performance were successfully prepared by second grade bauxite. The phase structure and the microstructure were investigated via X-Ray diffraction and scanning electron microscopy. The results suggested that bulk density and apparent density constantly increased, while the breakage ratio gradually decreased with the increasing in sintering temperature. When the sintering temperature reached to 1500°C, the breakage ratio obtained lowest value of 3.6% under 52 MPa closed pressure, which satisfied the requirement of Chinese Petroleum and Gas Industry standard. Furthermore, the mode of fracture for ceramic proppants was transformed from intergranular fracture into transgranular fracture and open pores had larger influence than closed pores for breakage ratio of ceramic proppants.     

Effects of CaCO3 additive on properties and microstructure of corundum- And mullite-based ceramic proppants

Corundum-mullite ceramic proppants have been successfully synthesized using raw materials of natural bauxite and solid waste coal gangue, CaCO₃, as additive. The influences of calcium carbonate additive on phase composition, microstructure, and mechanical performances were systematically investigated. The results indicate that the addition of CaCO₃ promotes the formation of liquid phase at lower temperature during sintering process, which is beneficial to the densification of the samples and the reduction of sintering temperature. Moreover, the mullite grains become finer and finer with the content of CaCO₃ additive increasing, which improves the toughness and strength of the samples via a grain refinement strengthening mechanism. The ceramic proppants exhibit optimal performances with additive of 5 wt.% at 1350°C, and the breakage ratio under 52 MPa closed pressure is the lowest. Additionally, the sintering temperature is dropped by 150°C compared with the samples without adding calcium carbonate.     

Effective reduction of sintering temperature and breakage ratio for a low‐cost ceramic proppant by feldspar addition

The second grade bauxite and feldspar were used to synthesize ceramic proppant materials. Phase structure and microstructure of the samples were studied by X‐ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. It was found that the feldspar, as a sintering aid, was beneficial to generate liquid phase during the sintering process. The formed liquid phase, not only promoted the densification of the samples, but also reduced the sintering temperature. With the content of feldspar increasing, the sintering temperature gradually decreased. When the content of feldspar was 4 wt.%, the breakage ratio of the samples was reduced to the lowest level of 2.2% at 1400°C under 52 MPa closed pressure, which met the requirement of Chinese Petroleum and Gas Industry Standard (SY/T 5108‐2014). Moreover, the sintering temperature was reduced by 100°C compared with the proppants without adding feldspar.     

Basic principle,progress, and prospects of coal gangue ceramic proppants

Ceramic proppants are preferred in hydraulic fracturing because of their high strength, good sphericity, and excellent acid corrosion resistance. Bauxite is the main raw material of ceramic proppants, but with the increasing depletion of bauxite resources, substitutes for bauxite need to be sought. Coal gangue is a solid waste that is rich in SiO₂ and Al₂O₃, making it a potential substitute for the preparation of ceramic proppants. The use of coal gangue to prepare ceramic proppants can reduce the cost of ceramic proppants and benefit environmental protection. Studies on using coal gangue to prepare ceramic proppants have been conducted and achieved progress, but further improvement can still be obtained. Here, the basic principle, progress, and prospects of coal gangue ceramic proppants are reviewed. First, coal gangue ceramic proppants are divided into two categories, namely, proppants prepared using coal gangue as an auxiliary material and proppants prepared using coal gangue as the main material. Second, the progress of research of coal gangue ceramic proppants is summarized from the perspective of additives, and the influence of different kinds of additives on the sintering temperature and performance of proppants is discussed. Lastly, the future prospects of coal gangue ceramic proppants are presented.     

压裂支撑剂的覆膜改性技术

针对油气田开发对压裂支撑剂的性能要求愈来愈高的产业重大需求,油田化学领域运用现代化学理论与技术,开展了一系列卓有成效的压裂支撑剂化学覆膜改性研究和产品研发,为油气工业的快速发展做出了突出贡献。本文从化学和工程两个视角,系统阐述了压裂支撑剂化学覆膜改性的研究方向。化学角度,主要研究方向包括：在支撑剂表面涂层构成化学覆膜、通过化学手段科学改变支撑剂表面特性、化学涂层与改性并举。工程角度,大致分为三个重要研究方向：一是通过在石英砂、陶粒等支撑剂表面涂敷覆膜来提升支撑剂强度;二是通过在石英砂、陶粒等支撑剂表面涂敷覆膜来降低整个支撑剂的相对密度（如自悬浮涂层技术等）;三是石英砂、陶粒等支撑剂表面涂敷覆膜实现堵水疏油的功能。本文还简要阐述了树脂覆膜支撑剂、疏水支撑剂、憎水憎油支撑剂、自悬浮支撑剂、自聚型支撑剂、无机聚合物涂覆支撑剂以及功能性支撑剂等主要产品的特性。展望支撑剂未来的发展趋势,提出支撑剂应向多功能、高性能、小尺寸和智能化方向发展以及开发出更加适合无水压裂的支撑剂和原位生成型自支撑压裂体系。     

SiC纳米线增强反应烧结碳化硅陶瓷的性能研究

以单晶SiC纳米线作为增强体,碳化硅-碳为陶瓷基体,在1550℃下,采用反应烧结制备碳化硅基陶瓷复合材料(SiCnf/SiC).结合X射线衍射、万能试验机和扫描电镜等检测和分析,研究SiC纳米线对复合材料的微结构和力学性能的影响.研究表明:与未加入SiC纳米线的反应烧结碳化硅陶瓷相比,添加SiC纳米线的复合陶瓷的抗弯强度和断裂韧性都得到显著的提高,抗弯强度提高了52％,达到320 MPa(SiC纳米线含量为12wt％),断裂韧性提高了40.6％,达到4.5 MPa· m1/2(SiC纳米线含量为15wt％);反应后的SiC纳米线仍然可以保持原有的竹节状结构,且随着SiC纳米线的加入,复合陶瓷的断口可以观察到SiC纳米线拔出现象.但由于SiC纳米线“架桥”的现象,添加过量的纳米线会降低复合陶瓷的密度和限制复合陶瓷力学性能的提高.同时还讨论了SiCnf/SiC的增强机理.