低渗非均质油藏注气提高采收率实验研究

Experimental Research on Improving Recovery of Low Permeability and Heteroneous Reservoir by Gas Injection

针对长庆油田某区块低渗透裂缝性油藏裂缝发育、非均质性严重的特点,通过实验研究了注入时机对氮气驱油效率的影响,优选氮气驱注入方式并对气液比和段塞大小进行了优化。实验结果表明:N2注入时机对原油采收率有较大影响,N2注入时机应尽早。气液交替注入方式更有利于低渗油藏特别是非均质油藏的开发。气液比和段塞大小对氮气驱开发效果均有显著影响,优选结果是气液比1∶1,氮气段塞个数为5。

As to the obvious charateristics of fracture abundance and severe hetorogeneity in certain block of fracture reservoir with low permeability of Changqing oilfield, the effect of injection time on nitrogeon flooding efficiency were studied with physical experiments, the injection ways of nitrogeon flooding and the gas-liquid ratio coupled with the size of slugs were optimized. The experimental results show that the injection time of N2 has significant effect on the oil recovery. That the N2 should be injected in the early stage of water producing. By the way of gas alternating liquid injection can be more infavor of the development of low-permeability reservoir, especially for that of heterogeneous reservoir. The gas-liquid ratio and the size of nitrogeon slug also have siginificant effect on the oil recovery, and the optimum gas-liquid ratio and the number of slug are respectively 1：1 and 5.