Xu, Tianguang¹ 
(1) IHS Energy, Houston, TX

ABSTRACT: Petroleum Systems and Plays of the Offshore Bohai Gulf Basin, China

The Offshore Bohai Gulf Basin, a Tertiary rift basin with strike-slip features, is located in northeast China. It covers an area of approximately 73,000 sq km. With the involvement of international oil companies, significant discoveries have been made in recent years. So far, proven reserve of about 1.5 bcm oil equivalent and current production of over 20,000 m3/d have been achieved in the offshore Bohai. Fifteen sags have been identified, containing mudstone source rocks of the Shahejie and Lower Dongying formations. However, considering these sags share the similar evolution history, two petroleum systems are generalized for the entire offshore Bohai. They are the Shahejie–Guantao/Minghuazhen and Lower Dongying–Guantao/Minghuazhen petroleum systems. More than 30 plays have been identified in the offshore Bohai, and these plays are grouped into three parent plays based on their genesis. These parent plays are pre-rift, syn-rift, and post-rift plays. The pre-rift basement play contains buried hill reservoirs, including pre-Tertiary karst-modified carbonates, fractured granites, clastic and volcanic rocks; and traps are typically structural and unconformity. The syn-rift deep play contains mainly clastic and minor carbonate reservoirs of the Lower Tertiary Shahejie and Dongying formations; and traps are mainly related to extensional normal faults and stratigraphic variations. The post-rift shallow play contains sandstone reservoirs of the Upper Tertiary Guantao and Minghuazhen formations; and traps are typically anticlinal and stratigraphic. Most significant discoveries have been made in the Upper Tertiary post-rift shallow play and it has been the major exploration target in the offshore Bohai Gulf Basin. 

AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.