Abstract: Aiming at Donghe sandstone oil reservoir with significantly titled oil-water contact in the Hadson Oilfield,Tarim Basin,an investigation into the origin of titled oil-water contact is conducted,which excludes the possibility that hydropower and capillary pressure resulted in the tilted contact.Structural evolution analysis and physical modeling show that the inclination of oilwater contact in sandstone oil reservoir results from tectonic inversion by neotectonic movement.The oil reservoir has been undergoing adjustment with evidently unsteady hydrocarbon accumulation,so a hint about theoretical presumption of unsteady hydrocarbon accumulation is given,in which the process from hydrocarbon generation and accumulation to hydrocarbon depletion is regarded as a continuous dynamic process and may be divided into pre-reservoir stage,reservoir stage and post-reservoir stage with different hydrocarbon accumulation style in different stages.

Key words: Hadson Oilfield, tilted oil-water contact, neotectonic movement, unsteady hydrocarbon accumulation, physical modeling, Tarim Basin