Hetian fault belt is one of the major fault belts along the southwest margin of Tarim Basin extending more than 300km and dipping south with dip angles of 20-60?.It cuts through the Upper Proterozoic to Pliocene strata and lay consealed under the Pliocene.It was initialed in Early Permian and has undergone several stages of evolution.High-dipping anticlines such as Piaman

Duwa

Sangzhu

Yuliqun and Pusalocate on the upthrown wall of this faul belt

whereas low dipping anticlinesas Keliyang and Kokyar on its downthrown side.Among them

the long-axial Keliyang anticline

screened by the north walls of Sangzhu and Yuliqun antic-linal structures

contains the favourable Middle Jurassic source rock and thepossible Eogene source rock.It is obvious that when the source material is matured in Late Miocene

the fault belt could be a fine passage for hydrocarbon migration

while synchronous Keliyang anticline provides a favourable space for hydrocarbon accumulation during Late Miocene-Pliocene.In accordance with the fact that secondary oil and gas pools are discover-ed in Miocene Series of Kokyar structure

and oil shows corp out on the north walls of Sangzhu and Yuliqun structures

the author points out that Keliyang subtle structure could be inferred to have good petroleum potential.