特低渗非均质油藏水窜后提高波及效率研究

Researches on Improving Sweep Efficiency After Water Breakthrough in Ultra-low Permeability Heterogeneous Reservoir

针对特低渗油藏水驱开发易窜流、调剖治理效果差等问题,开展了特低渗非均质油藏治理窜流、提高波及效率的室内模拟实验。层内非均质储层模型调剖驱油实验表明,特低渗非均质油藏调剖后水驱与中高渗油藏相比后续注入压力高,难以提高波及效率;水驱后直接转注天然气,气体继续沿水窜通道流动;但采用调剖后天然气驱,不仅后续注入压力低,且能够提高采收率约7.8%,气驱后还可间歇注气进一步提高采收率约9.6%。因此,特低渗油藏水窜后应采用调剖后气驱的调剖驱油方式,可有效扩大驱油剂的波及体积,提高采收率。

Focusing on the water channeling and the bad results of profile control in ultra-low permeability reservoir,the laboratory simulation experiments were conducted to study the anti-channeling and expanding sweep volume methods.The experiments of profile control and oil displacement were run in the reservoir models with interlayer heterogeneity,which shows that,the water injection pressure after profile control is higher than that in mid-high permeability reservoir,and it is difficult to improve the sweep efficiency in ultra-low permeability reservoir.Gas flows along water channeling path when injected directly after water flooding.Injecting gas after profile control can not only reduce the subsequent injection pressure but also improve the recovery by about 7.8%.The recovery can be improved by about 9.6%in the intermittent gas injection process after gas flooding.Therefore,injecting gas after profile control can be used after water channeling in ultra-low permeability reservoir to effectively expand sweep volume and improve the recovery.