石油学报 ›› 2016, Vol. 37 ›› Issue (10): 1287-1292.DOI: 10.7623/syxb201610009

• 石油工程 • 上一篇    下一篇

油井水泥浆液-固态演变的结构与性能

程小伟1,2, 刘开强1, 李早元2, 郭小阳2   

  1. 1. 西南石油大学材料科学与工程学院 四川成都 610500;
    2. 西南石油大学油气藏地质及开发工程国家重点实验室 四川成都 610500
  • 收稿日期:2015-11-19 修回日期:2016-09-02 出版日期:2016-10-25 发布日期:2016-11-09
  • 通讯作者: 郭小阳,男,1951年5月生,1977年获西南石油大学学士学位,现为西南石油大学教授、博士生导师,主要从事固井材料与固井工程研究。Email:guoxiaoyangswpi@126.com
  • 作者简介:程小伟,男,1977年8月生,2002年获四川大学学士学位,2009年获西南石油大学博士学位,现为西南石油大学副教授,主要从事固井材料与固井工艺研究。Email:cxw0261@sina.com
  • 基金资助:

    国家重点基础研究发展计划(973)项目“固井工程用高耐蚀高韧性水泥基材料的研究与应用”(2016YFB0303602)、国家自然科学基金面上项目“基于多相渗透理论的环空气窜机理及应用基础研究”(No.51574203)资助。

Structure and properties of oil well cement slurry during liquid-solid transition

Cheng Xiaowei1,2, Liu Kaiqiang1, Li Zaoyuan2, Guo Xiaoyang2   

  1. 1. School of Materials Science and Engineering, Southwest Petroleum University, Sichuan Chengdu 610500, China;
    2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Sichuan Chengdu 610500, China
  • Received:2015-11-19 Revised:2016-09-02 Online:2016-10-25 Published:2016-11-09

摘要:

固井水泥浆“失重”对固井质量具有严重影响,而固井水泥浆在液-固态转变过程中的结构和性能变化与“失重”密切相关。因此,通过XRD测试、TG测试及机械性能分析仪对固井水泥浆的液-固态转变过程中的性能演变进行分析;并结合环境扫描电子显微镜(ESEM)及新的制样方法定点观察水泥浆液-固态过程中的微观形貌。研究发现:固井水泥浆在液-固态转变中,Ca(OH)2的生成速率明显增加,水化反应速率加快;随着水泥浆水化反应的进行,水泥颗粒被无定形的水化产物覆盖,使水泥浆颗粒之间相互支撑,让液-固态转变过程的水泥浆呈“骨架-孔隙结构”,降低水泥颗粒的流动性能;而随着水化反应的进一步进行,孔隙溶液中自由水量的降低,溶液中水化产物则结晶长大,降低了水泥浆中的孔隙率,使水泥浆的孔隙水压力不能有效传递,从而使水泥浆在液-固态转变过程中“失重”;并使水泥颗粒之间由物理键连接转变为化学键连接,增加水泥石抗压强度,降低水泥石的泊松比。

关键词: 液-固态转变, 微观结构, 力学性能, 水化产物, 失重

Abstract:

Weight loss of cement slurry has a significant impact on the cementing quality, and the variation of structure and properties in cement slurry during liquid-solid transition are closely related to weight loss. Consequently, this paper aimed to investigate the evolution of cement slurry properties during liquid-solid transition by tests using X-ray diffraction (XRD), thermogravimetry (TG) and mechanical analyzer. In combination with Environmental Scanning Electron Microscope (ESEM) and new sampling method, a fixed-point observation was conducted on the micro-morphology of cement slurry in the liquid-solid transition process. The research showed that during liquid-solid transition, the formation rate of Ca(OH)2 and the hydration rate were remarkably increased; as the hydration of cement slurry progressed, the cement particles were gradually covered by amorphous hydration products, thus forming a support structure among cement particles. For this reason, the cement slurry presents a skeleton-pore structure in the liquid-solid transition process, which can decrease the flowing property of cement particles. As the hydration process continued, the free water content in pore solution was reduced, while hydration products were crystallized and enlarged, which will reduced the porosity of cement slurry and block the effective transmission of water pressure in pores, therefore causing weight loss in the liquid-solid transition process. Meanwhile, the physical bonding between cement particles changed into chemical bonding, thus leading to an increase in compressive strength and a decrease in the Poisson's ratio of cement stone.

Key words: liquid-solid transition, microstructure, mechanical properties, hydration products, weight loss

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