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Hydrocarbon Migration Phenomena and Their Relation to Charge Efficiency: A Review


The ability to accurately predict hydrocarbon volumes at the prospect level hinges heavily on our understanding of hydrocarbon charge efficiencies. Charge efficiency reflects the amount of hydrocarbons that arrives and is preserved at the trap compared with the total generated hydrocarbon volume. This includes efficiencies related to expulsion (primary migration), secondary migration, entrapment, and preservation. Building on work since the early 1980s (e.g., Jones, 1980; Sluijk and Nederlof, 1984), recent efforts have focused on addressing controls on and uncertainties in migration efficiency, such as examining timing relationships (He, 2016), hydrocarbon phase (Stainforth, 2016), and attempting to quantify migration losses (Muscio et al., 2016). Likewise, in the past several decades of literature, observations of migration processes have been made that imply varying degrees of migration efficiency. These migration scenarios, which include phenomena such as expulsion lag and migration shadows, have been evoked as explanations for how those traps were charged. Here, we review these and other examples of migration phenomena including migration lag, hoteling/remigration, fill-and-spill migration routes, and long-distance lateral migration. The primary purpose of this review is to provide context for ongoing efforts in improving our understanding of migration and a foundation for evaluating new prospects with poorly-defined migration risks. Initial observations suggest that the migration phenomena are linked to migration efficiency and overall charge efficiency, but are the product of a confluence of multiple geologic factors. Our observations indicate that charge efficiencies are highly site-specific. Implicit in this level of specificity is that, even in petroleum provinces that are developmentally mature and are known to possess working petroleum systems, adequate charge to that particular prospect may be a potential risk because of the possibility of hydrocarbon loss with respect to that trap. A future application of this catalog is to validate the observations in literature by relating them to stochastically-determined migration efficiencies (Muscio et al., 2016) from analogous settings with geologic factors that purportedly influence migration. This review also informs our efforts in identifying and high-grading potentially key geologic controls on migration efficiency.