基于参数不确定性的井筒失效风险评价研究

Evaluation on Wellbore Failure Based on Parameter Uncertainty

目前井筒完整性的相关研究大都未考虑温度的影响,也没有成形的、针对套管和水泥环统一的失效风险评价方法。为此,以深水高温高压完井测试井筒为研究对象,基于参数不确定性影响进行研究,建立一套综合考虑套管和水泥环的井筒完整性失效风险评价方法。研究结果表明:所得评价方法对风险具有较高敏感性,提高套管强度会降低套管失效风险,而环空圈闭压力只重点影响封固井段风险;水泥环的抗压和抗拉失效分别造成固井界面微环隙和本体径向裂缝,弹性模量与泊松比分别主要影响水泥环的抗压与抗拉失效风险,可以通过增大水泥环材料韧性来提高水泥环密封。研究结论可为井筒完整性的保护和深水高温高压完井测试作业的顺利进行提供理论指导。

Most studies on wellbore integrity have not considered the influence of temperature,and there is no unified evaluation method for failure of casing and cement sheath.A study was conducted on the deepwater high-temperature and high-pressure completion test wellbore considering the influence of parameter uncertainty,and a method of evaluation on wellbore integrity failure considering the casing and cement sheath was established.The results show that the proposed method is highly sensitive to risks.The improvement of casing strength reduces the casing failure risk,while the annular trapped pressure only focuses on affecting the risk of cemented section.The compressive and tensile failures of cement sheath cause micro annulus at cementing interface and radial cracks on the cement sheath respectively.The elastic modulus and Poisson's ratio mainly affect the compressive and tensile failure risks of cement sheath respectively.The sealing of cement sheath can be improved by increasing the toughness of cement sheath materials.The conclusions provide theoretical guidance for the protection of wellbore integrity and the performance of deepwater high-temperature and high-pressure completion test.