Looking for the Mother Lode of the Pearl River Mouth Basin, China

William Dickson¹, James Granath², Mark E. Odegard³, and Janice M. Christ^4
1Dickson International Geosciences (DIGs), Houston, TX
²Consultant, Highlands Ranch, CO
³Grizzly Geosciences, Inc. (GrizGeo), Sugar Land, TX
⁴Consultant, The Woodlands, TX

With Husky’s June 2006 announcement of the significant Liwan gas discovery in the Pearl River Mouth Basin, we updated our analysis of petroleum system elements (AAPG, 2002, "Finding the Pearl in the Pearl River Mouth Basin, Offshore China: A Deepwater Turbidite Oil Play?"). Greatly improved data allow us to infer a multi-block productive trend with high potential for oil as well as gas. This paper illustrates play components and estimates feature size and distribution.

New regional mapping of basement depth and sediment thickness reveals a 7 - 10 km thick pod of pre-Neogene sediments. This "Mother of Pearl" sediment volume contains the oil-prone source rocks typical of the South China Margin. A sediment thick covers the southern half of the Baiyun Sag, crossing blocks 42/05 and 29/26, thinning across neighboring blocks. The presence of oil will depend on protection of traps from gas flushing. A thinner pod within the adjacent North Shuangfeng Basin (NSB) is more likely to contain liquid hydrocarbons but lies in deeper water.

The extent and thickness of sediments are controlled by Early Tertiary relay faults that segmented the extensional margin and connected the fault-bounded depocenters. They defined the sediment conveyor belts into the basin. Channel and catchment mapping was refined and extended with new gravity and magnetic data, suggesting fan-prone sub-areas. Reservoirs will be present as turbidites, predicted in our earlier paper, demonstrated on CNOOC seismic data published since 2002, and confirmed by the Liwan discovery.

AAPG Search and Discovery Article #90078©2008 AAPG Annual Convention, San Antonio, Texas