国内地下储气库钻完井技术现状分析

国内已投入运行的储气库暴露出了环空带压问题，严重地影响了储气库安全平稳运行。为此，详细介绍了国外储气库建设在注采井寿命、钻井方式及井型、井身结构、钻进工艺、固井、完井、老井封堵和注采等方面采用的最新理念和技术。针对国内在建和拟建地下储气库的基本情况，着重分析了环空带压、井身结构、钻井施工、固井、老井处理、关键工具和装备以及规范和标准等方面存在的主要问题。结果认为：①国内储气库建设各方逐渐接受了储气层采用大尺寸井眼且储层专打的井身结构理念；②钻井应以提高固井质量为核心，把套管丝扣气密封检测、弹性水泥浆、IBC测井等先进技术应用于技术套管和生产套管固井；③要高度重视地下储气库注采井和老井的井筒完整性管理。最后指出应建立适合国内地质特点的储气库钻完井工程设计和施工技术规范；需专项研究低压储气库钻井防漏堵漏和储层保护等技术并研制油套管氦气气密封检测等装备与工具。

Drilling and completion technologies for the underground gas storage (UGS) in China : A state-of-the-art appraisal

Both research and construction of underground gas storage (UGS) started late in China, and the annular abnormal pressure in drilling has brought about trouble in normal operation of those in service UGSs. In view of this, this paper first introduces in detail the newest ideas and advanced techniques associated with international UGS in terms of life spans of injection and production wells, drilling methods and well types, well structure, drilling technology, cementing and completion, plugging, injection and production of mature wells, and so on. Then, this paper analyzes the basic information of those UGS projects planned or under construction, focusing on such major issues as circular abnormal pressure, well structure, drilling operation, well completion and cementing, processing of mature wells, important tools and equipments, as well as the involved criteria and regulations. The following conclusions are drawn. (1) The new concept of casing program specially designed for gas reservoirs with large size bore holes being adopted has been gradually accepted by all the participators of UGS project construction. (2) Cementing quality is the core of drilling operation so the advanced techniques like air tight seal inspection, elastic cement, isolation scanner are used for intermediate and production casings in well cementing. (3) Great attention should be paid to the well integrity management of injection, production and mature wells in the USG construction. On this basis, the following proposals are presented. (1) Design codes and technical regulations should be established for well completion in UGS projects based on domestic geological conditions. (2) Special studies should be conducted on the technologies for loss circulation control and reservoir protection as well as the development and research of special equipment and tools for helium leak check in casing strings.