文23储气库封堵井完整性保障技术

文23储气库属于枯竭砂岩气藏型储气库，建设前需要对无法再利用的老井进行封堵。为确保老井的封堵质量，保障储气库的完整性，引入挪威石油工业协会井筒完整性技术标准的井筒完整性设计理念，识别了文23储气库老井封堵前后的窜漏风险状况，设计了井屏障系统，研发了适用于高温气层的耐高温缓膨气密封封堵体系，制定了确保封堵老井井筒完整性的工艺，形成了以井屏障设计、施工和监控为基础的井筒完整性保障技术。文23储气库老井采用该技术进行封堵，现场施工成功率100％，老井封堵后的井筒完整性良好，经受住多轮次注采交变应力的长期作用。研究和现场应用结果表明，根据井筒完整性设计理念进行井筒完整性设计和施工，可以确保老井封堵后井筒长期的完整性，也可为类似储气库设计提供借鉴。 

Integrity Assurance Technologies for Plugged Wells in Wen 23 Gas Storage

As Wen 23 Gas Storage is a depleted sandstone gas reservoir, old wells that can no longer be reused need to be plugged before its construction. To guarantee the effectiveness of plugging old wells and assure the integrity of the gas storage, the design concept of wellbore integrity of the technical standard formulated by the Norwegian Oil Industry Association was adopted, and risks of channeling and leakage before and after plugging of the old wells in Wen 23 Gas Storage were identified. Furthermore, a well barrier system was drawn, a heat-resistant swelling-delayed gas-tight plugging system suitable for high-temperature gas layers was developed, and process designed to ensure the wellbore integrity of plugged old wells was created. Assurance technologies for wellbore integrity based on the design, construction, and monitoring of the well barrier were thus obtained and then applied to plug the old wells in Wen 23 Gas Storage. In addition to achieving a 100% success rate of field construction and favorable wellbore integrity after plugging, these wells also survived the long-standing action of alternating stresses during multiple rounds of injection and production. The research results and field application show that conducting wellbore integrity-oriented design and construction according to wellbore integrity can not only ensure the long-term wellbore integrity of old wells after they are plugged but also provide a reference for the design of similar gas storages.