大庆油田低渗透油层注水伤害实验研究

Research on damage test of water injection in low permeability reservoir of Daqing Oilfield

通过天然岩心的注水伤害实验,总结出了低渗透率油层条件下,注入水中悬浮物粒径、悬浮物含量、含油量、硫酸还原菌含量与岩心渗透率下降幅度的关系。分析实验结果得出:①对于空气渗透率低于50×10-3μm2油层,要使注入水不对油层产生较大伤害,注入水中的悬浮物粒径应小于1.6μm,悬浮物含量低于3 mg/L,含油量低于8 mg/L,硫酸还原菌含量少于100个/mL;②按照注水标准严格控制注水水质,注入水对地层的伤害程度不明显,注25倍孔隙体积的注入水后,油层渗透率的下降率一般不会超过30%;③超标注水将会对油层造成伤害,伤害后的油层再注入达到水质标准的合格水,油层渗透率无法恢复。

Through the damage test of water injected into natural core, the relationship of grain size and content of soliquoid in the injected water, oil content, content of sulfuric acid redox cellunder and the permeability decreasing degree of core has beeu coucluded in the low permeability reservoir. The analysis of test result shows：① for the oil lavers with air perlueability lower thau 50×10^-3μm^2, the grain size soliquoid should be less than 1.6μm, content 3mg/L ,oil conteut 8mg/L, couteut of sulfuric acid redox cellunder 100 unit/mL ,respectively , so as to avoid the damage of injected water to oil layers;②quality of injected water should be rigorously controlled according to water inje：tion criterion, so the daluage of injected water to the forlnation will uot be district, and the decreasing rate of reservoir permeability will not surpass 30% after 25PV water was injected ;③super - standard injected water would cause damage to the formation, whose permeability could uot be resumed although normal water reaching the water quality criteria is inj, cted again.