孔隙型碳酸盐岩储层注气注水提高采收率试验

Experiments on gas and water injection for enhanced oil recovery in porous carbonate reservoir

关键词:  油藏  孔隙型碳酸盐储层  混相驱  非混驱  水驱效率

Key words:  reservoir  porous carbonate reservoir  miscible flooding  immiscible flooding  water flooding efficiency

摘要:

中东地区部分碳酸盐岩储层类型以孔隙型为主,裂缝不发育,气测渗透率低,流体物性较差。以中东某油田S油藏为例,开展注气和注水可行性试验研究,并探讨其提高采收率的微观渗流机制。结果表明:受物性特征影响,储层注伴生气驱最小混相压力高,地层条件下不易达到混相驱替,但整体上岩心注烃类气驱效率要高于水驱效率,尤其当达到混相条件时,气驱效率明显提高;注烃类非混相驱油效率也相对较高,主要是由于储层原油黏度较高,气驱使原油体积膨胀,黏度降低,进而改善流动性;试验采用的水驱和气驱方式在微观上主要动用大孔隙中的可动流体,可考虑优化驱替方式进一步提高驱油效率。

Abstract:

In Middle-East area, there are some porous carbonate reservoirs with low permeability, few fractures and relatively poor fluid properties. Taking S reservoir as example, the gas and water injection experiments were carried out, and microscope seepage mechanism of EOR was researched. The results show that under formation conditions, miscible associated gas flooding is not achieved easily because of high minimum miscible pressure. The flooding efficiency of hydrocarbon gas injection is higher than that of water injection, especially in the condition of miscible flooding. The immiscible flooding efficiency of gas injection is relatively high, because gas flooding makes oil volume expanse and viscosity decrease, and then oil mobility is improved. In the experiments, water injection and gas injection mainly displace mobile oil in micropore, so changing displacement manner should be considered to improve flooding efficiency further.