AAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Finding New Reserves in Mature Basins Through Simulation of Dynamic Hydrocarbon Migration and Accumulation, Dongying Depression, Bohai Bay Basin, China
(1) Shengli Oilfield Branch Company, China Petroleum & Chemical Corp., Dongying, China.
(2) Key Laboratory of Petroleum Resources Research, Chinese Academy of Sciences, Beijing, China.
Large oil and gas fields can still be discovered in well-explored petroliferous basins. This is demonstrated by recent success achieved through advanced research on dynamic processes of hydrocarbon migration and accumulation in Dongying Depression. The depression is a typical Paleogene rift basin in the Bohai Bay Basin, where exploration in nearly half a century has produced a large amount of oil and gas. This study focuses on the Wang-Jia-Gang Oilfield on the southern slope of Niu-Zhuang Sag in Dongying Depression. The abundant subsurface data of this field was used to characterize the opening and closing processes of faults to reconstruct the temporal-spatial relationship between faulting and fluid flow during the critical moment of source-rock maturation and accumulation. Diagenetic study of sandstone carriers and their hydraulic connectivity for hydrocarbon migration indicates that sandstone permeability can be used to effectively quantify the hydraulic connectivity of the carrier system. Spatial juxtaposition among sandstones and connecting open faults was identified to construct the 2-D framework of compound sandstone-fault carrier system in the area of major secondary migration.
Next, hydrocarbon migration pathways within the reconstructed carrier system during the principal migration-accumulation period were simulated on the basis of current understanding of migration process in the Paleogene petroleum systems, using our Mig-MOD migration simulator. Major migration pathways of variable directions and distance and quantity of migrated hydrocarbon through the pathways were interpreted from the model results, using a new mass-balance method. The method takes into account the distribution of simulated pathways and estimated hydrocarbon loss during migration. The interpretation indicates that hydrocarbons could have migrated over a long distance outside of the source domain in the center of the depression to areas beyond discovered oil fields. These areas are new exploration targets.