Abstract The hydraulic fracturing process involves high pump pressure and large displacement, which increase the risk of debonding on the interface of the cement sheath and rock formation. Therefore, in this study, a three-dimensional numerical calculation model of casing-cement sheath-formation assembly was established, and the failure mechanism of the bonding surface caused by fracturing due to fluid migration was investigated. The effects of the cement sheath’s Young’s modulus and Poisson’s ratio, bonding strength, perforation azimuth angle, and non-uniform in-situ stress on the anti-debonding ability of the cement-to-formation interface were analyzed. Finally, the following conclusions were drawn: The calculation results show that the failure of the bonding surface is greatly affected by the bonding strength, and its anti-debonding ability significantly increases linearly with increasing bonding strength. Furthermore, while increasing the Young’s modulus improves the anti-debonding ability, the Poisson’s ratio of the cement sheath and the perforation azimuth angle have little effect. Under non-uniform in-situ stress, the anti-debonding ability decreases with the increase of the difference between the horizontal and vertical in-situ stress. Thus, the non-uniform in-situ stress accelerates the failure of the bonding surface.

中文翻译：

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页岩气井水力压裂水泥-地层界面脱粘数值模拟

摘要 水力压裂过程泵压大、排量大，增加了水泥环与岩层界面脱粘的风险。为此，本研究建立套管-水泥护套-地层组合三维数值计算模型，研究流体运移压裂导致胶结面破坏机理。分析了水泥环的杨氏模量和泊松比、结合强度、射孔方位角和非均匀地应力对水泥-地层界面抗脱粘能力的影响。最后得出以下结论： 计算结果表明，结合面的破坏受结合强度的影响很大，并且其抗脱粘能力随着粘合强度的增加而显着线性增加。此外，提高杨氏模量在提高抗脱胶能力的同时，水泥环泊松比和射孔方位角影响不大。在非均匀地应力下，抗剥离能力随着水平和垂直地应力差值的增大而降低。因此，不均匀的原位应力加速了结合表面的失效。抗脱粘能力随着水平和垂直地应力差的增加而降低。因此，不均匀的原位应力加速了结合表面的失效。抗脱粘能力随着水平和垂直地应力差的增加而降低。因此，不均匀的原位应力加速了结合表面的失效。