THERMAL SCIENCE

International Scientific Journal

Thermal Science - Online First

online first only

Experimental study on the thermal damage characteristics of cement stone

ABSTRACT
Aiming at the problem of cement ring sealing failure during deep high-temperature shale gas exploitation, comprehensively considering the influence of the characteristics of multi-cluster fracturing of multiple horizontal wells and formation temperature, the cementing cement the southwest region is taken as the research object. After exposure to different temperatures (95°C and 135°C) and for different times (5, 10 and 20 times), axial and triaxial tests with different confining pressures (0, 5 MPa, 15 MPa and 30 MPa) were carried out. The research shows that: (1) the stress-strain curve of cement stone after heat treatment can be divided into four stages: compaction, elastic, yield and post-peak stage. As the confining pressure increases, the compaction phase disappears, the yield phase increases, and we see the transition from brittle to ideal plasticity after the peak; (2) as the temperature and number of thermal cycles increase, the cohesive force decreases significantly, and the internal friction angle shows a slight increase. The elastic modulus and the peak strength decreased.
KEYWORDS
PAPER SUBMITTED: 2020-06-18
PAPER REVISED: 2020-09-06
PAPER ACCEPTED: 2020-09-27
PUBLISHED ONLINE: 2020-10-31
DOI REFERENCE: https://doi.org/10.2298/TSCI200618317X
REFERENCES
  1. National Energy Administration. Shale Gas Development Plan (2016-2020). Beijing, China, 2016.
  2. Xia, Y. B., et al., Analysis of the technical difficulties of shale gas well cementing (in Chinese), Natural Gas Exploration and Development, 39 (2016), 1, pp. 74-76
  3. Xu, F., et al., Effect of the drilling fluid on hardness characteristics of tight sandstone, Current science, 115 (2018), 11, pp. 2015-2018.
  4. Qi, F. Z., et al., Analysis of Causes of Gas Well Annulus Pressure and Solutions (in Chinese), Meeting of Directors of Petroleum Drilling Institute, 2008, pp. 802-806.
  5. Saint-Marc, J., et al., Initial state of stress: the key to achieving long-term cement-sheath integrity. SPE Annual Technical Conference and Exhibition, Society of Petroleum Engineers, 2008.
  6. Sun, K. Zh., et al., Cementing Technology for Deep Shale Gas Horizontal Well in the Dingshan Block, Petroleum Drilling Techniques, 43 (2015), 3, pp. 55-60.
  7. Xu, F., et al., Effect of bedding planes on wave velocity and AE characteristics of the Longmaxi shale in China, Arabian Journal of Geosciences, 10 (2017), 6, pp. 1-10.
  8. Tao, Q., Chen, X. X., Causal analysis and countermeasures on B sustained casing pressure of shale-gas horizontal wells in the Sichuan Basin (in Chinese), Oil Drilling & Production Technology, 39 (2017), 5, pp. 588-593.
  9. Wang, L., et al., Experimental study on mechanical properties of oil well cement under high temperature (in Chinese), Journal of China University of Petroleum (Edition of Natural Science), 42 (2018), 6, pp. 93-100.
  10. Du, H., et al., Microstructure and Micromechanics of Wellbore Cements under Compression and Thermal Loading, American Rock Mechanics Association. 2015.
  11. Li, Z. Y., et al., Improvement of latex on mechanical deformation capability of cement sheath under triaxial loading condition (in Chinese), Acta Petrolei Sinica, 28 (2007), 4, pp. 126-129.
  12. Li, Z. Y., et al., Deformation Behavior of Oil-Well Cement Stone under Confining Pressure (in Chinese), Natural Gas Industry, 27 (2007), 9, pp. 62-64.
  13. Zheng, Y. Zh., et al., Mechanical behaviors of cement systems in different conditions (in Chinese), Natural Gas Industry, 37 (2017), 1, pp. 119-123.
  14. Xu, F., et al., Effect of confining pressure on the mechanical properties of thermally treated sandstone, Current science, 112 (2017), 6, pp. 1101-1106.