元坝气田超深酸性气藏完井投产关键技术

元坝气田是中石化继普光气田后在四川盆地发现的又一个千亿立方米级储量的大型气田,也是国内目前埋藏最深的海相碳酸盐岩酸性气藏。其主力储层上二叠统长兴组具有超深、高温、高含硫、富含CO_2、气水关系复杂等特征,完井作业面临的工程地质条件复杂,井型及完井方式多样,作业难度大。为此,中石化西南石油工程有限公司通过攻关研究及实践,形成了完井试气及地面控制、深度酸压改造、元坝超深小井眼井筒处理、微牙痕上扣及气密封检测、安全管控等一系列完井投产关键配套技术,攻克了气田开发过程中的管柱防腐、储层深度酸化压裂、高产测试、安全管控等世界级完井投产工程技术难题,成功应用近40口井,为该气田34×10~8 m~3天然气产能建设目标的完成提供了重要的技术支撑。

Key technologies for well completion and commissioning of ultra-deep sour gas reservoirs in the Yuanba Gasfield,Sichuan Basin

The Yuanba Gasfield is another large gas field with reserves of a hundred billion cubic meters that was discovered by Sinopec after the Puguang Gasfield in the Sichuan Basin. At present, it is the deepest marine carbonate sour gas field in China. Its principal reservoir, the Upper Permian Changxing Fm is characterized by ultra depth, high temperature, high sulfur content, high CO₂ content, and complex gas–water relationship. Therefore, well completion is faced with complicated engineering geological conditions, diverse well types and well completion modes and high-difficulty operation. In view of this, Sinopec Southwest Petroleum Engineering Co., Ltd. carried out technical research and practice. As a result, a series of key well completion and commissioning technologies were developed, including well completion testing and ground control, in-depth acid fracturing stimulation, ultra-deep slim-hole wellbore processing, micro-tooth mark make-up and air tightness detection, and safety control. Based on these technologies, the worldwide technical difficulties of well completion and commissioning in the process of gas field development are settled, such as string corrosion prevention, in-depth acid fracturing, high-yield testing, and safety control. These technologies have been applied successfully in nearly 40 wells, providing an important technical support for the realization of 34×10⁸ m³ annual gas production capacity construction in the Yuanba Gasfield.