Secondary hydrocarbon migration

Secondary hydrocarbon migration is the movement of hydrocarbons after expulsion from a source rock through carrier and reservoir rocks or fault and fracture systems. 

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Schowalter, T.T. Mechanics of secondary hydrocarbon migration and entrapment,, 4 ssoc. Pet. Geol. Bull., 63(5) 723-760,1979. 

Secondary hydrocarbon migration under hydrostatic conditions... 

Secondary hydrocarbon migration generally occurs through water-saturated sedimentary rocks, i.e. through rocks that are water-wet. As water is generally considered a perfect wetting fluid (Schowalter, 1979), the contact angle 0 in Equation 4.14 for hydrocarbon-water-rock systems can be taken to be zero. If, in addition, the hydrocarbon-water interface is assumed to be spherical, then Equation 4.14 becomes identical with Equation 4.13. 

At the start of secondary hydrocarbon migration, i.e. in the vicinity of the source rocks, the migration direction of both hydrocarbons in aqueous solution and hydrocarbons in very fine suspension (Section 4.2.1) are strongly influenced by the direction of groundwater flow. 

The factors of influence on secondary hydrocarbon migration vary on large temporal and spatial scales (Section 4.3.1). 

The secondary hydrocarbon migration system in a basin at a certain moment during its evolution can be characterized by the masses and initial composition of the petroleum hydrocarbons available for secondary migration, the three-dimensional pattern of secondary hydrocarbon migration, i.e. the directions and lengths of the hydrocarbon migration paths, the flux of... 

Hydrostatic secondary hydrocarbon migration systems, in which the dominant forces influencing hydrocarbon migration are the buoyancy forces and the capillary pressure gradients (Section 4.3.3). 

Under hydrostatic conditions the basin-wide secondary hydrocarbon migration patterns and consequently also the final distribution of the oil and gas accumulations in a sedimentary basin are closely linked to the stable basin geometry present during hydrocarbon expulsion from the source rocks. 

The system of hydrodynamic secondary hydrocarbon migration, whether the hydrocarbons move in separate phase, in very fine suspension or in aqueous solution, is influenced by the porosity and permeability distribution in a sedimentary basin, and the magnitude and direction of the net driving force for groundwater flow. As a consequence, the different processes and associated forces that are responsible for the hydrodynamic conditions in a sedimentary basin also determine to a greater or less extent the characteristics of the hydrocarbon migration system in a hydrodynamic basin (Sections 4.3.4.1, 4.S.4.2 and4.3.4.3). 

Secondary hydrocarbon migration in actively filling and subsiding basins... 

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