Petroleum Resource Assessment Through Classifying Hydrocarbon Migration Stages and Their Associated Accumulation Types

Abstract

Understanding the hydrocarbon (HC) migration characteristics in basin studies would significantly increase the chance of success in both conventional and unconventional exploration. Integrated basin modeling is the primary technique serving this purpose. But due to the entangled geologic processes and uncertainties in the modeling, some fundamental and useful HC migration properties have been overlooked. This study presents an approach of assessing HC entrapment type and HC potential through identifying migration stages and their evolution. Three migration stages are present when the HC migration process is disentangled from the complicated geologic setting. Stage I represents the saturation of petroleum in a bulk source interval, where a significant amount of unconventional reserves exist. Stage II denotes an initial merging stage, where the HCs begin to concentrate into accumulations away from source rocks. These accumulations have a high migration efficiency but may be associated with limited fetch area. Stage III signifies the further merging and concentrating of HCs out of the Stage II. It also includes remigration of HCs from previous traps due to structural modification. This stage tends to have more complex HC migration processes and a lower migration efficiency than Stage II. In a sedimentary basin, however, not all the three stages will fully develop or be preserved as a consequence of various geologic processes. The evolution and the preservation of migration stages can be used as indirect indicators of the associated HC entrapment behaviors. The identification and characterization of these different stages of a basin can be implemented through analyzing factors such as source rock quality, maturation history, lateral stratigraphic heterogeneity, nature of the regional seal, and structural evolution. They will provide reference for basin modeling and stochastic analysis on the associated migration efficiency, the likelihood of HC entrapment, and the potential volumes. Comparisons of the discovered and modeled HC resource densities from plays in multiple basin studies provide the foundation for this assessment and demonstrate how this classification scheme can assist with the risking of HC charge presence and volumes.

AAPG Datapages/Search and Discovery Article #90291 ©2017 AAPG Annual Convention and Exhibition, Houston, Texas, April 2-5, 2017