SCB experimental study on fracture mechanical properties of cement

被引：0
|
作者：
Chen L. [1 ,2 ]
Wang S. [2 ,3 ]
Zhang D. [2 ]
机构：
[1] School of Mining and Technology, Inner Mongolia University of Technology, Hohhot
[2] State Key Laboratory of Coal and CBM Co-mining, Jincheng Anthracite Mining Group, Jincheng
[3] Faculty of Earth Resources, China University of Geosciences, Wuhan
来源：
Natural Gas Industry | 2021年 / 41卷 / 09期
关键词：
Brittle-ductile fracture; Cementing; Deep coalbed methane well; Fiber oil-well cement (FC); Fracture energy dissipation; Mode I fracture toughness; Pure oil-well cement (PC); SCB test; Water immersion;
D O I：
10.3787/j.issn.1000-0976.2021.09.011
中图分类号：
学科分类号：
摘要：
A semi-circular bending (SCB) test was carried out to analyze the fracture mechanical properties of pure cement (PC) and fiber cement (FC) specimens used in coalbed methane (CBM) wells under the conditions of drying, water immersion and mineralized water immersion. The objective of this study was to provide a theoretical basis for optimizing the cementing material of deep CBM well, improving the durability of wellbore annulus structure and evaluating, and predicting the isolation capacity scientifically. Loading displacement-load curves and specimen fracture rates showed that the fracture type of PC specimen is brittle fracture while that of FC specimen is similar to the ductile fracture of metal. Under the same conditions, the fracture rate of PC specimen was about 10 times that of FC specimen. Under the conditions of drying, water immersion and mineralized water immersion, the fracture toughness of PC specimen is 0.53, 0.36 and 0.40 MPa•m0.5, and that of FC specimen is 0.49, 0.35 and 0.39 MPa•m0.5, respectively. The calculation results of material fracture energy dissipation showed the energy dissipation of FC in the whole process of compression fracture was about 20-30 times that of PC under the same condition of environmental media. Under dry condition, oil-well cement specimen preferentially fractured at the mineral grain boundary, which resulted in rough fractures or tortuous fracture paths. In the environment of water immersion and mineralized water immersion, however, the cement specimen fractured mostly along the mineral dissolution defects, so as to form straight cracks.
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页码：105 / 113
页数：8
相关论文
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