元坝气田长兴组生物礁气藏特征及开发对策

四川盆地元坝气田是世界上已发现埋藏最深的高含硫碳酸盐岩气田,上二叠统长兴组生物礁气藏具有埋藏超深,礁体小、散、多期,储层薄、物性差、非均质性强,流体分布复杂,直井产量低等特点;气藏开发面临礁相白云岩储层时空展布规律研究需不断深化,小礁体精细刻画与薄储层定量预测困难,水平井部署与优化设计影响因素众多,长水平段水平井长穿优质薄储层难度大等诸多难题。为实现对该气田的高效开发,开展了生物礁储层分布规律与发育模式研究、小礁体精细刻画与薄储层定量预测、条带状小礁体气藏水平井优化设计、超深薄储层水平井轨迹实时优化调整等技术攻关。相关系列攻关成果有力地支撑了元坝气田的开发建设,建成了我国首个超深高含硫生物礁大气田,混合气产能可达40×10~8m~3/a。该气田的成功投产,一方面奠定了我国在高含硫气田开发领域的领先地位;另一方面,对保障"川气东送"沿线六省两市70多个城市的长期稳定供气,对促进中西部产业结构调整和沿江区域经济发展也具有重大意义。

Characteristics of the Changxing Fm biohermal gas reservoir in the Yuanba Gasfield,Sichuan Basin and development countermeasures

Located in the Sichuan Basin, the Yuanba Gasfield is the deepest high-sulfur carbonate gas field among those discovered in the world. Its biohermal gas reservoir of the Upper Permian Changxing Fm is characterized by ultra depth, multi-stage small and scattered reef, thin reservoir, poor physical properties, strong heterogeneity, complex fluid distribution, and low production of vertical wells. The development of the biohermal gas reservoir is subject to many difficulties. For example, it is necessary to deepen the studies on time-space distribution laws of reef dolomite reservoirs; it is difficult to characterize small reefs precisely and predict thin reservoirs quantitatively; the deployment and optimization design of horizontal wells are influenced by multiple factors; and the difficulty for horizontal wells with long horizontal sections to run through high-quality thin reservoirs is high. In order to develop the Yuanba Gasfield efficiently, therefore, it is necessary to carry out a series of technical researches on the distribution laws and development models of biohermal reservoirs, precise characterization of small reefs, quantitative prediction of thin reservoirs, optimization design of horizontal wells in banded small reef gas reservoirs, and real-time trajectory optimization and adjustment of horizontal wells in ultra-deep thin reservoirs. These research results provide a powerful support for the development and construction of the Yuanba Gasfield. Based on these technologies, China's first ultra-deep high-sulfur large biohermal gas field was built with a mixed gas annual production capacity of 40×108 m3. The successful commissioning of the Yuanba Gasfield lays a basis for the leading position of China in the field of high-sulfur gas field development. In addition, it is of great significance to the long-term stable gas supply in 70 cities of six provinces and two municipalities along the "Sichuan-to-East China Gas Transmission Pipeline", as well as to the industrial structure adjustment in central–western China and the economic development along the Yangtze River.