元坝地区复杂尾管固井难点与对策

Difficulties and Countermeasures for Complex Liner Cementing in Yuanba Area

川东北气田元坝地区尾管固井具有超深、高温、高压以及封固段超长、压力窗口狭窄、压稳与防漏矛盾突出等特点,固井后易出现气窜、顶部超缓凝,部分井封固段上部还有盐膏层,使用厚壁套管会使固井难度更大。经过多井次的探索和应用,在井眼准备、水泥外加剂以及现场施工工艺3个方面初步形成了深层天然气井固井配套技术,如采用新型的分段气窜预测模型,优选防气窜能力强的水泥浆体系等措施,在元坝1-1侧1井固井应用中取得了良好的效果,满足了气田开发对固井质量高标准的要求。

In Yuanba area of northeastern Sichuan gasfield, the liner cementing is characterized by some difficulties, such as ex-tra-deep depth, high pressure and temperature, extra-long isola-tion section, narrow pressure window, and an outstanding conflict of both pressure stabilizing and leakage proof. Meanwhile, gas channeling and super-retarding at the top may easily occur after cementing. In addition, there is an evaporite bed existing in the up-per section for some wells, which brings about a big difficulty to ce-menting when thick wall casing is used. In this study, the cement-ing in many wells is explored, the basic theory of cementing tech-nology used for deep gas wells is studied, and the cementing matching technology used for deep gas wells is formed in terms of borehole preparation, cement additive and site operation technolo-gy, which can meet the requirement of gasfield development to high cementing quality.