塔河油田井组注氮气提高采收率技术

塔河油田碳酸盐岩缝洞型油藏经过多年开发后底水锥进，水驱效果逐渐变差，剩余油主要以阁楼油的形式富集。为了提高油藏开发效果，2014 年塔河油田在A 单元探索多井缝洞单元井组注氮气先导试验，开展井组注气后一年间邻井受效逐渐显现，截至2015 年8 月已增油3×104 t，说明井组注氮气可以有效驱替井间阁楼油。试验结果表明，高注低采井组注气量高、见效慢、波及体积大，而低注高采井组见效快但是易发生气窜，井组注氮气采油技术是一种提高采收率的有效技术手段。

Enhancing oil recovery by nitrogen injection in well group of Tahe Oilfield

Over years of development, the carbonate fracture-cavity reservoirs in the Tahe Oilfield suffered bottom water coning,making the waterflooding effect become gradually poor, and the remaining oil is mainly enriched in the form of attic oil. For the purpose of improving the reservoir development effect, a pilot test of nitrogen injection in well group was conducted in the multiwell fracturecavity unit A of the Tahe Oilfield in 2014. The response of offset wells gradually appeared. As to August 2015, 3×104 t incremental oil had been obtained, showing that the nitrogen injection in well group can effectively displace the interwell attic oil. The pilot test results show that the well group of injection in high permeability layer and production from low permeability layer is characterized by high gas injection rate, slow response and large swept volume, whereas the well group of injection in low permeability layer and production from high permeability layer is characterized by fast response but easy gas breakthrough. The oil recovery technology of nitrogen injection in well group is an effective technique for enhancing the oil recovery.