28 years has passed since the discovery of Karamay Oilfield in 1955

how-ever

the right understanding of its tectonic feature is obtained only in recent few years.The cognition process of the Ke-Wu fault belt

by which the enriched zone of petroleum are essentially controlled

has gone through three stages

i.e.firstly it was considered as a reverse fault

then as a overthrust

and now it is recognized as a huge nappe.Its forming process started in the middle-late stage of Hercynian movement

took shape in Indo-China movement and ended in Yenshanian movement.Therefore

it is mostly covered by Jurassic and Cretace-ous systems.This conceptual progress has thus promoted the exploration to a completely new level of development and brought about enormous economic effect.Four key targets have been suggested for petroleum prospecting within the nappe belt:1)

the front fault-block zone of the nappe

2)

the main body of the nappe

3)

the footwall of the nappe as well as its front

4)

the pinch out zone of the overlying strata(J-K)above the nappe.The author believes that huge reserve of petroleum will be exploited in the future within these targets.Explorers have also recognized that the source rock of this oilfield should be essentially related to Carboniferous marine sediments

not Permian as sup-posed before.