关停井与报废井的井筒完整性

Well integrity of shut-in well & abandonment well

我国发布了废弃井及长停井处置指南与标准;挪威NORSOK D-010 V4标准有4种井:暂停井、暂时报废井、永久报废井、永久报废1个井段;美国加州油气监管局有对长停井、闲置井、遗弃井、报废井的监管法规。通过分析几种不同的分类标准法规,从内涵上梳理归纳为关停井与报废井2大类。研究了关停井与报废井的井筒屏障结构,列举了关停井(暂时报废井)和永久报废井2类井筒屏障的实例图解(共18个)并进行了分析说明。从这些实例中说明关停井与报废井是井筒生命周期内难以完全避免的,必须重视对它们的井筒完整性和井筒屏障及其组件的设计与应用并进行标准化、规范化管理;应根据各个具体井的实际状况设计"量身定制"井筒屏障及其组件并采取有关措施,以确保关停井与报废井的井筒完整性和关停、报废期间的安全,保护油气层、地下水和环境;要特别重视对渗透性地层、储集层、入流源的封隔封堵。每口关停井、报废井都要用多层套管、水泥环封堵环空,用多个水泥塞和机械封隔工具封堵管内;研究了水泥塞的位置、类型、施工方法、质量要求;指出了一些容易发生和忽视的问题,提出了检查、监测、处理意见,并用5个图例予以说明。

China has issued the disposal guideline and standard on abandonment well and inactive well. According to Norway’s standard NORSOK D-010 V4, there are 4 types of wells, i.e., suspension well, temporary abandonment of well, permanent abandonment of wells and permanent abandonment of a section in a well. The California Oil and Gas Regulatory Authority of America enacts the supervision regulations on inactive well, idle well, orphan well and abandonment well. In this paper, these classification standards and regulations were analyzed, and two categories (i.e., shut-in well and abandonment well) were classified and summarized based on the connotation. Then, the structures of well barriers in shut-in well and abandonment well were investigated, and 18 barrier schematics of shut-in well (temporary abandonment well) and permanent abandonment well were illustrated. It is demonstrated that shut-in well and abandonment well cannot be avoided completely in the service life of well, so it is necessary to focus on their well integrity & well barrier and the design and application of its elements and carry out standardized management. The well barrier of each specific well and its elements shall be customized based on its actual situation, and related measures shall be taken to ensure the well integrity of shut-in well and abandonment well and their safety in the periods of shut in and abandonment so as to protect oil and gas layers, underground water and environment. And attention shall be especially paid to the blocking and plugging of permeable formation, reservoir and inflow source. As for each shut-in well or abandonment well, the annulus shall be plugged with multi-layer casing and cement sheath, and the inside of the tubing shall be plugged by using multiple cement plugs and mechanical plugging tools. Finally, the position, type, construction method and quality requirement of cement plug were studied. In addition, some problems that are likely to occur and be ignored were pointed out, and the methods of design acceptance, monitoring and treatment were put forward and described based on 5 schematics.