Abstract:

The oilfield water in xidaliyia,Tahe-1,Tahe-3 and Tahe-4 Oilfields in Northern Tarim Basin has similar ionic composition,and the principal compositions of soluble materials are consistent with sea water,suggesting its marine origin.The different ionic compositions and concentration indicate different geological features.HCO₃^- has positive coherence with the strata density,the concentration differences of SO₄^2-,Ca²⁺,Mg²⁺ indicate different origin of the water.The content of I^- is determined by physical features of crude oil but not lithologic feature,and bears negative coherence with the density of crude oil.When concentration of Br^- in oilfield water is more than 350 mg/L,the oil would be condensate oil.

Key words: oilfield water, characteristic ion, geological significance, North Tarim Oilfield