Abstract: With oil and gas exploration and development unfolded continuously, the targets for exploration and development are becoming more and more complicated. The wells with a long open-hole, a large temperature differential, and co-existence of a multiple of pressure systems pose a stern challenge for safety of cementing service and guarantee of cementing quality. A series of problems often appear in cementing service, such as extra retarded set and poor cementing quality, thus affecting safe and high-efficiency development of deep-layer oil and gas resources. Focusing on the technological bottleneck in long-cementing interval of deep well under the large temperature differential condition, CNPC developed special cement slurry fluid loss agents and retarders suitable for cementing under large temperature differential condition, following study of the cement hydrogen mechanism and molecular structural design of cement admixtures. Meanwhile, CNPC also designed a cement slurry system suitable for different temperature ranges. The systematic process technology for large temperature differential cementing was developed by integration of the latest applicable technologies, such as large temperature difference cement slurry system, high efficient flushing spacer, improving displacement efficiency, antichanneling cementing, and safe tripping-in of casing. The process technology has been successfully used for more than 1100 wells in the oil and gas fields of Tarim, Southwest, Changqing and Huabei as well as CNPC’s overseas oilfields in Central Asia, providing the necessary technology for simplification of wellbore structure, cost reduction and improvement of cementing quality. As exploration and development is extending into deep and complicated layers, cementing technology for long cementing interval under large temperature difference condition shows a prominent technological advantage, with a bright prospect for wide application.

摘要： 当前油气勘探开发对象日趋复杂，深井超深井钻井数量增多，长裸眼、大温差、多套压力系统并存井给 固井安全施工及质量保障带来严峻挑战，固井中易出现的超缓凝、固井质量差等问题，影响了深层油气资源的安全高 效开发。针对深井长封固段大温差固井技术难题，研究水泥水化机理，结合水泥外加剂分子结构设计，开发出了适用 于大温差条件固井的水泥浆降失水剂及缓凝剂，设计了适合不同温差范围的水泥浆体系。通过大温差水泥浆体系、高 效冲洗隔离液、提高顶替效率、平衡压力固井、套管安全下入等方面先进适用技术的集成，形成了大温差固井配套工 艺技术，在塔里木、西南、长庆、华北等油气田及海外中亚地区成功应用1100 多口井，为简化井身结构、降低成本、 提高固井质量提供了技术保障。随着勘探开发向深层和复杂地层的深入，大温差长封固段固井技术优势突出，应用前 景广阔。

关键词: 油气井固井, 长封固段, 大温差, 降失水剂, 缓凝剂, 水泥浆, 固井质量