Well integrity of shut-in well & abandonment well

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.