井下二次分离同井注采技术在特高含水区块适用性分析

Applicability analysis of downhole secondary separation with injection-production technology in the same well in ultra-high water-cut block

针对含水率超过99%的采油井,为进一步降低同井注采井的地面产液量,基于井下一次分离同井注采技术,利用两个水力旋流器串联,形成井下二次分离同井注采技术。通过室内实验得出,新型水力旋流器分离效率更高,分流比为15%~45%时,最大分离效率达到98.5%。现场试验验证了井下二次分离同井注采技术可行性,可将特高含水井的产液量降低至15%以内,实现了特高含水井组复产。同时,结合油藏工程,通过对注采层系优化设计,改变注水方向,对常规注采驱替“死角”进行了有效驱替,提高了采油井采收率,减少地面注水,极大地降低采油成本,为实现特高含水区块经济有效动用探索了一种新的模式。

For production wells with water cut of more than 99%,in order to further reduce the surface liquid production of the injection-production wells in the same well,two hydro-cyclones were connected in series to form the downhole secondary separation with injection-production technology in the same well based on the downhole primary separation with injection-production in the same well.The indoor experiment showed that the separation efficiency of the new hydro-cyclone was higher.When the separation ratio was from 15%to 45%,the maximum separation efficiency reached to 98.5%.Field tests have proved the feasibility of downhole secondary separation with injection-production technology in the same well,which could reduce the liquid production of ultra-high water cut wells to less than 15%,so as to realize the re-production in ultra-high water-cut well groups.At the same time,combined with reservoir engineering,by optimizing the design of injection-production strata,changing the water injection direction,the“dead corner”occurred in the conventional injection-production displacement has been effectively displaced to improve the recovery of oil production wells,reduce surface water injection,and greatly reduce the oil production cost,so as to explore a new model for realizing the effective and economic production in ultra-high water-cut blocks.