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针对由井眼崩落造成的椭圆形井眼的井壁稳定问题,基于岩石力学、弹塑性力学等相关理论,通过建立不同椭圆度井眼的有限元计算模型,采用Mohr-coulomb塑性准则作为其本构模型,在利用圆形井眼稳定性理论对有限元计算模型验证的基础上,获得了不同椭圆度井眼的围岩应力和应变,从而得出了椭圆度与井壁应力与应变的关系。结果表明,随着椭圆度的增大,塑性区变大,即高应力区向远处岩层深入,且椭圆形井眼在最小地应力方向应力更加集中。
Aiming at the wellbore stability of oval wellbore caused by wellbore collapse, based on the related theories of rock mechanics and elasto-plastic mechanics, the finite element model of different ellipticity boreholes and the Mohr-coulomb plasticity criterion Model, the stress and strain of the surrounding rock of different oval boreholes were obtained based on the verification of the finite element model by using the theory of circular wellbore stability. The relationship between the ellipticity and the stress and strain of the wellbore was obtained. The results show that with the increase of ellipticity, the plastic zone becomes larger, that is, the high stress zone goes deeper into the rock formation, and the stress of elliptical wellbore in the direction of the minimum stress is more concentrated.