缝洞型油藏超深井注氮气提高采收率技术

塔河碳酸盐岩油藏非均质性强，溶洞是最主要的储集空间，裂缝主要起连通通道作用，储集体中流体以管流模式为主，储集体类型复杂导致对剩余油分布认识不清，前期主要依靠弹性和水驱开发，采收率较低。目前塔河油田缝洞型油藏注水开发后期面临挖潜困难、剩余油储量难以动用的情况，注氮气驱油工艺的提出为解决这一难题提供了思路和方法。通过对注入气源的选择、地面注入工艺的优化、井口及管柱优化，成功实现了气水混注降压工艺及多轮次注气—机抽生产转换作业，节约了成本，提高了生产时效，减少了施工风险。该研究为碳酸盐岩油藏注气提高采收率工作提供了新的借鉴。

Ultra-deep wells in fractured-vuggy reservoir nitrogen injection EOR technology

Tahe carbonate reservoir shows strong heterogeneity. The cavern is the primary reservoir space while fracture is mainly plays a role of connecting channel in this reservoir. The fluids in reservoir are mainly taking the form of pipe flow model. Complex reservoir type lead to the remaining oil distribution is unclear and early development mainly relies on elastic drive and water flooding with low recovery efficiency in this oilfield. At present, this fractured-vuggy reservoir within later stage of water flooding faces the difficulties of potential tapping and remaining oil reserves difficult to use, and nitrogen injection for oil flooding process provides an ideas and methods to solve this problem. Through injecting gas source selection, optimization of injection process on the ground and wellhead and string optimization, the technique successful realizes the gas-water mixed injection pressure decreasing technology and multi-turn gas injection and machine pumping switching. The implementation of this technology saves the cost, and improves production efficiency and reduces the safety risk. The research provides a new idea and method for gas injection enhancing oil recovery efficiency of carbonate reservoir.