考虑多因素的固井二界面胶结抗拉强度室内评价方法

A Laboratory Method for Evaluating the Bonding Tensile Strength of the Cement–Formation Interface Considering Multiple Factors

杨春和 王磊 曾义金 郭印同 杨广国 刘奎

YANG Chunhe WANG Lei ZENG Yijin GUO Yintong YANG Guangguo LIU Kui

岩土力学与工程国家重点实验室（中国科学院武汉岩土力学研究所），湖北武汉 430071 中石化石油工程技术研究院有限公司，北京 102206

State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei, 430071, China Sinopec Research Institute of Petroleum Engineering Co., Ltd., Beijing, 102206, China

受井壁表面粗糙度、钻井液残留和温压扰动等因素的影响，固井二界面是整个环空封隔的最薄弱环节，且极易发生张拉破坏导致环空密封失效，但已有的评价方法只能获得固井二界面的胶结剪切强度，不能很好地评价固井二界面抗拉破裂性能。为此，考虑岩性、界面粗糙度、钻井液残留、冲洗液清洗和水泥浆等主要因素，建立了一种固井二界面胶结抗拉强度室内评价方法，从冲洗效率、胶结细观结构、抗拉强度、破裂形貌等多个维度对固井二界面胶结抗拉性能进行了系统评价。研究结果表明，该评价方法科学合理、步骤清晰、简单适用、试验结果离散性小，不同因素下测试结果区分度好，进一步完善了固井二界面胶结强度评价方法，具有较高的推广应用价值。

Due to the influence of surface roughness of wellbore walls, residual drilling fluids, and temperature perturbation, the cement–formation interface is the weakest link in the whole annulus sealing system. Additionally, tensile fracture is prone to occur and can lead to annulus sealing failure. The existing evaluation methods, however, can only determine the bonding shear strength of the cement–formation interface and cannot adequately evaluate its bonding tensile property. Therefore, a laboratory method was established to evaluate the bonding tensile strength of the cement–formation interface. This method took into consideration the main factors such as lithology, interface roughness, drilling fluid deposit, flushing fluid washing, and cement slurry. It systematically evaluated the bonding tensile strength of the cement–formation interface from multiple perspectives, including the flushing efficiency, the mesoscopic structure of bonding, tensile strength, and fracture morphology. Results from the research suggest that the proposed method is scientific and reasonable, and it reveals clear steps, simple application, and small discreteness of test results, and the test results are discriminative under different factors. Hence, the method improves the evaluation method for the bonding strength of the cement–formation interface and merits dissemination.

国家自然科学基金项目“高强压裂交变荷载下深部页岩储层固井二界面密封失效机理研究”（编号：52104010）和“复杂环境下水泥环全生命周期密封理论与控制方法”（编号：U22B6003）、中国石化科技攻关项目“深层页岩气井固井水泥环失效机理与密封性评价方法研究”（编号：P21056）联合资助

https://doi.org/10.11911/syztjs.2023041