Reservoir-forming characteristics of Baiyinchagan Sag in Erlian Basin

The oil and gas exploration in Baiyinchagan Sag, Erlian Basin, has been 30 years, with no breakthrough until 2003. In the area of being thought with no oil, some high-yielding prolific fields and high-quality scale reserves have been discovered, by reexamining the old data to establish a new reservoir formation pattern, and with new exploration concepts, from resource evaluation, major structural background optimization and big sand body searching and its combination with structural background, to applying 3D seismic technology and other technologies to identify the traps of small structures, faulted blocks and sand bodies. Many new fields have been discovered, such as Sanghe, West Sanghe, Daerqi, West Daerqi, West Wengte and Xilinhaolai, with proved oil in place up to several tens of million tons and an additional annual capacity of 10×104 t. The exploration history and experience in Baiyinchagan Sag will throw new light for risk exploration of other old sags.