Evaluation of fracture mechanical properties of set cement in CBM wells by the indentation method

被引：0
|
作者：
Zhang D. [1 ,2 ]
Chen L. [1 ,3 ]
Wang S. [1 ,4 ]
机构：
[1] State Key Laboratory of Coal and CBM Co-Mining, Jincheng Anthracite Mining Group, Jincheng, 048012, Shanxi
[2] Shanxi Jincheng Anthracite Mining Group Co., Ltd., Jincheng, 048006, Shanxi
[3] School of Mining and Technology, Inner Mongolia University of Technology, Hohhot, 010051, Inner Mongolia
[4] Faculty of Earth Resources, China University of Geosciences - Wuhan, Wuhan, 430074, Hubei
来源：
Natural Gas Industry | 2020年 / 40卷 / 03期
关键词：
CBM well; Deep; Fracture toughness; High-toughness cement; Impact resistant; Indentation method; Sealing capacity of annulus; Set cement; Well cementing;
D O I：
10.3787/j.issn.1000-0976.2020.03.014
中图分类号：
TU52 [非金属材料]; TV4 [水工材料];
学科分类号：
0805 ; 081503 ;
摘要：
The sealing capacity of wellbore annulus has to satisfy stricter requirements under complex working conditions, such as high-pressure injection fracturing of deep coalbed methane (CBM) well, multi-stage fracturing of horizontal well and CO2 geological sequestration. The original appearance damage characteristics of set cement in CBM wells was characterized and the effects of the fracture mechanical properties of set cement on the failure of annulus sealing were studied by analyzing the downhole cementing situations of CBM wells in the Jincheng mining area of the Qinshui Basin on the basis of field observation. The damage situations of the cement sheath in the wellbore annulus of CBM wells were investigated. The Vickers hardness and fracture toughness tests were conducted on the original set cement samples of CBM wells using the indentation method. The change laws of hardness and fracture toughness under different loads were analyzed. The main wellbore sealing failure forms of CBM wells include the fluid channels which are generated by the cracking of the first and second interfaces of cement sheath and the high-angle vertical fractures and fault blocks which are formed by the brittle fracturing of cement sheath. Due to the high brittleness of set cement, the hardness decreased firstly and then increased with the increase of indenter load. The high brittleness of existing cementing slurry systems is a key intrinsic factor leading to the sealing failure in the stages of perforation and fracturing. The fracture toughness increased gradually with the increase of indenter load, and then maintained at 0.71 MPa·m1/2 in the late stage when the crack resistance was poorer. Radiation cracks were formed in set cement under the impact of perforating projectile. During the fracturing, the injection of high-pressure fluid led to the instability and propagation of radiation cracks and the formation of vertical fracture channeling and fault blocks.
引用
收藏
页码：115 / 122
页数：7
相关论文
共 22 条
  • [1] Nelson E.B., Guillot D., Well Cementing, (2006)
  • [2] Palmer I., Coalbed methane completions: A world view, International Journal of Coal Geology, 82, 3-4, pp. 184-195, (2010)
  • [3] Chao J., Li J., Liu G., Et al., Analysis of the influence of cement sheath failure on sustained casing pressure in shale gas wells, Journal of Natural Gas Science and Engineering, 66, pp. 244-254, (2019)
  • [4] Li J., Gong N., Li Z., Et al., Progress in studying cement sheath failure in perforated wells, Drilling Fluid & Completion Fluid, 33, 6, pp. 10-16, (2016)
  • [5] Zheng Y., Xu B., Pu J., Et al., Mechanical behaviors of cement systems in different conditions, Natural Gas Industry, 37, 1, pp. 119-123, (2017)
  • [6] Wu Z., Liu S., Geng Y., Et al., Evaluation technology for isolation capacity of cement sheath in HTHP high-sulfur gas wells, Oil Drilling & Production Technology, 38, 6, pp. 787-790, (2016)
  • [7] Guo X., Gu T., Li Z., Et al., Corrosion mechanism of hydrogen sulfide on well cement under water wet environments, Natural Gas Industry, 35, 10, pp. 93-98, (2015)
  • [8] Omosebi O., Maheshwari H., Ahmed R., Et al., Experimental study of the effects of CO<sub>2</sub> concentration and pressure at elevated temperature on the mechanical integrity of oil and gas well cement, Journal of Natural Gas Science and Engineering, 44, pp. 299-313, (2017)
  • [9] Liu J., Liu S., Liu H., Effect of carbon nanotubes on micro mechanical properties of well-cementing cement stone by nanoindentation technique, Bulletin of the Chinese Ceramic Society, 38, 4, pp. 1263-1268, (2019)
  • [10] Yan S., Yan S., Wu Y., Et al., Effect of functional materials on mechanical properties of hardened cement paste, Oil Drilling & Production Technology, 40, 2, pp. 174-178, (2018)
123