Experimental research on compatibility of water and sewage mixed injection for reservoir flooding in QK17-2 Oil Field

Water and sewage mixed injection for reservoir flooding is commonly used in offshore oilfield with middle and high water cut.Since June 2009 the operation of water sewage mixed injection in QK17-2 oil field,the acidification valid period from 9 months down to 3 months.Experiment research on compatibility of the produced water and the fresh water was conducted to analyze the change of injection water quality after mixing.The results show that: the mixing liquid has certain calcium carbonate scaling tendency with different proportion of fresh and produced water.And the calcium ion concentration decreased while concentration of suspended solids increased in the mixed fluid.The compatibility experimental results show that sewage water and fresh water is slight non-compatibility,and the degree of compatibility has accelerated trend with increasing of produced water proportion,temperature increment and the mix-time extension.