低渗透复杂油气藏提高采收率技术研究

Study on enhanced oil recovery technology for low permeability complex oil and gas reservoirs

针对低渗透复杂油气藏勘探开发难度大,采取常规提高采收率措施无法达到良好效果的问题,为进一步提高低渗透复杂油气藏的采收率,开展了注CO_(2)吞吐提高采收率的技术研究。室内试验结果表明,随着注气压力的升高、焖井时间的延长以及岩心渗透率的增大,注CO_(2)吞吐提高采收率的效果更加显著,而随着吞吐周期的增加,采收率逐渐降低。室内试验得到的最优施工参数为注气压力25 MPa,焖井时间6 h,吞吐周期3个。岩心渗透率越高,吞吐效果越好。现场应用结果表明,区块内4口油井实施注CO_(2)吞吐提高采收率技术措施后,日产油量由5.1 t/d显著提升至12.6 t/d,含水率由65.0%降低至33.4%。注CO_(2)吞吐措施能够有效提高低渗透复杂油气藏的采收率。

The exploration and development of low-permeability complex oil and gas reservoirs is usually difficult,and conventional measures to improve oil recovery are often unable to achieve good results.In order to further improve the oil recovery of low-permeability complex fault block reservoirs,the research on CO_(2)huff and puff technology to improve oil recovery is carried out.The laboratory test results show that with the increase of gas injection pressure,soaking time and core permeability,the effect of CO_(2)huff and puff is better,and with the increase of huff and puff cycles,the recovery factor decreases gradually.The optimal construction parameters obtained from indoor experiments are gas injection pressure of 25 MPa,soaking time of 6 h,and three cycles of huff and puff.The higher the permeability of the core,the better the huff and puff effect.The on-site application results show that after implementing the CO_(2)huff and puff technology measures to improve oil recovery in four oil wells in the block,the daily oil production is significantly increased from 5.1 t/d to 12.6 t/d,and the water content is decreased from 65.0%to 33.4%.CO_(2)huff and puff measures can effectively improve the recovery efficiency of low permeability complex fault block reservoirs.