Wellbore stability is a key challenge for oil and gas industry since it adds a great deal of additional cost to the industry. Traditional wellbore stability models such as elastic and poroelastic models may not produce reliable stress field around a wellbore since they consider isothermal wellbore condition. During the drilling phase, the drilling fluid temperature is different from the formation temperature due to geothermal gradient and circulation of the fluid inside the wellbore. Therefore, the assumption of isothermal condition will not predict the correct wellbore stability condition, especially for high pressure and high temperature wells. Hence, consideration of a thermoporoelastic model in stress estimation is more appropriate. Although there are several thermoporoelastic models in the literature, they employ the assumption of local thermal equilibrium (LTE) in their modeling. However, thermal properties of phases in a porous medium are rarely similar. This dissimilarity evokes the validation of LTE assumption. The local thermal non-equilibrium assumption ignores additional pore and thermal stresses in the porous medium caused by temperature variations of the fluid and solid phases. Under pure heat conduction, LTE is valid if thermal boundary conditions in a medium is constant or thermal conductivities of phases are similar according to Vadasz (2005) 1. Hence, using a local thermal non-equilibrium (LTNE) approach is required to establish each phase temperature, and update thermoporoelastic model accordingly. In this paper, the effects of induced thermal stresses on wellbore stress resolution and LTNE on thermoporoelastic model around a wellbore during drilling phase are investigated in low and high permeable formations. The LTNE thermoporoelastic model developed herein is a transient model considering conductive and convective heat transfers.

井筒稳定性是石油和天然气行业面临的主要挑战，因为它给行业增加了许多额外成本。传统的井眼稳定性模型（例如弹性和多孔弹性模型）可能不会在井眼周围产生可靠的应力场，因为它们考虑了等温井眼条件。在钻井阶段，由于地热梯度和井筒内流体的循环，钻井液温度与地层温度不同。因此，等温条件的假设将无法预测正确的井筒稳定性条件，尤其是对于高压和高温井而言。因此，在应力估计中考虑热多孔弹性模型更为合适。尽管文献中有几种热多孔弹性模型，他们在模型中采用了局部热平衡（LTE）的假设。但是，多孔介质中各相的热性质很少相似。这种差异引起了LTE假设的验证。局部热不平衡假设忽略了由于流体和固相温度变化而在多孔介质中产生的附加孔隙和热应力。根据Vadasz（2005）1，在纯热传导下，如果介质中的热边界条件恒定或相的热导率相似，则LTE有效。因此，需要使用局部热非平衡（LTNE）方法来建立每种相温度，并相应地更新热多孔弹性模型。在本文中，在低渗透率和高渗透率地层中，研究了在钻井阶段诱导热应力对井眼应力分辨率的影响以及对井眼周围的热孔隙弹性模型的LTNE的影响。本文开发的LTNE热多孔弹性模型是考虑传导和对流传热的瞬态模型。