Abstract: The major production horizon of multizone commingled oil well is normally determined by using production logging, zonal testing and tracer logging. However, they are expensive, time consuming, sometimes done with well shut-in or off production, and even easily resulting in damage of oil zones in process of operation. This paper suggests that the horizon of multizone commingled oil well can be effectively identified using gas chromatographic fingerprint feature and differences of gas chromatograph- mass spectrographic fingerprint properties as well as hydrocarbon fingerprint variations of commingled crude oil, and makes suggestions of production adjustment as required taking this type of horizon identification in Liaohe oilfield as an example. The result shows that the applied effectiveness is emerging obviously.

Key words: hydrocarbon, fingerprint technique, commingled oil production, oil formation