缝洞型碳酸盐岩凝析气藏提高采收率关键技术

EOR technologies for fractured-vuggy carbonate condensate gas reservoirs

中国海相碳酸盐岩资源丰富,主要以缝洞型碳酸盐岩油气藏为主,占天然气探明储量的2/3以上。其中塔里木盆地缝洞型碳酸盐岩凝析气藏埋深达4 500~7 000 m,储层非均质性极强、储集渗流介质复杂多样、流体性质复杂、气藏静态描述工作难度非常大,为储量评价、开发方案设计及开发动态分析带来了诸多挑战。为此,为了进一步提高该类型油气藏的采收率,以动态补静态,采用静态与动态紧密结合的方式提高气藏描述精度,并在多年的动静态研究和开发实践基础上,创新形成了缝洞型碳酸盐岩凝析气藏提高采收率关键技术。研究结果表明:①基于地震反演信息、以三维数值试井为核心的沙漠强衰减区高精度缝洞体动静迭代动态描述技术;②缝洞型凝析气藏一井多靶点立体开发提高储量动用技术;③缝洞型凝析气藏气举降压提高采收率技术。结论认为,形成的技术体系较好解决了缝洞体精细描述、提高储量动用、降低废弃压力等开发方面的关键难题,实现了对断裂带及羽状破碎带储层的精细描述与开发关键指标的准确预测,有效井及高效井的部署成功率比规模建产初期提高了26%,为缝洞型碳酸盐岩凝析气藏的科学有效开发提供了有力的技术支撑和经验借鉴。

There are abundant marine carbonate rock resources in China, which are dominated by fractured-vuggy carbonate oil and gas reservoirs accounting for over two thirds of proved reserves. The fractured-vuggy carbonate condensate gas reservoir in the Tarim Basin is at a burial depth of 4 500-7 000 m with the characteristics of extremely strong reservoir heterogeneity, complicated and diverse reservoir seepage media, complex fluid properties and quite difficult static characterization, which brings many challenges to reserve evaluation,development plan design and performance analysis. In order to improve the recovery factor of this type of oil and gas reservoir, this paper takes the dynamic characterization to supplement the static characterization and combines the two to improve the accuracy. In addition,based on many years’ of dynamic and static research and development practice, the key EOR technologies for fractured-vuggy carbonate condensate gas reservoirs are innovatively developed, such as the high-accuracy dynamic characterization technology with dynamic and static iteration for fractured-vuggy body in the strongly attenuated area of desert by taking seismic inversion information as the basis and 3D numerical well test as the core, the multi-target tridimensional development technology in one well to improve reserve production of fractured-vuggy condensate gas reservoirs, and the gas-lift depressurization EOR technology for fractured-vuggy condensate gas reservoirs. In conclusion, this technological system better solves the key difficulties in the fine characterization of fractured-vuggy body,reserve production improvement and abandonment pressure reduction of well. What’s more, it realizes the fine reservoir characterization of fractured zones and feather-shaped fractured zones and the accurate prediction of key development indexes, and increases the deployment success rate of effective wells and efficient wells by 26% compared with that in the initial stage of large-scale productivity construction. To sum up, these technologies provide powerful technical support and reference experience for the scientific and efficient development of fractured-vuggy carbonate condensate gas reservoirs.