一种带保护层的套管及其环空密封性

A new casing with protective layer and its annular sealing performance

针对高套管压力井出现的环空密封失效问题,设计一种能够减轻高套管交变内压力对水泥环的挤压破坏的套管,并将其命名为抗压及保护型套管(compression resistance&protection casing,CRP套管)。建立井筒的多层厚壁圆筒模型,分析水泥环内壁的最大径向应力和位移;建立试验设备验证设计的工程可行性,并通过控制温压模拟实际井筒工况。计算结果表明相较于常规套管,CRP套管水泥环内壁的最大径向应力和位移的降低幅度分别为20.75%~26.66%和33.3%~76.8%,理论上可以保护水泥环密封完整性;试验中CRP套管能够使水泥环多承受19.4 MPa的套管压力,证明了该套管良好的工程可行性。

Aiming at the failure of annulus sealing integrity in high casing pressure wells,a new casing was designed to reduce the crushing failure of cement sheath caused by the alternating high casing pressure,which is named as compression resistance&protection casing(CRP casing).A multi-layers thick wall cylinder model of the wellbore was established to calculate the maximum radial stress and displacement of the inner wall of the cement sheath.Then,an experimental facility was built to verify the engineering feasibility of the CRP casing under actual wellbore pressure and temperature conditions.The calculation results show that,comparing with the conventional casing,the maximum radial stress and displacement of the inner wall of cement sheath in the wellbore using the CRP casing can be decreased by 20.75%-26.66%and 33.3%-76.8%,respectively,which indicates the CRP casing can effectively protect the cement sheath.The experimental results demonstrate that the CRP casing can make the cement sheath bear more casing pressure of 19.4 MPa.