Continuous separate phase hydrocarbon migration

Organic matter / kerogen in source rocks occurs primarily in a solid finely disseminated condition, but is often very inhomogeneously distributed being concentrated in layers (Momper, 1978 Jones, 1980). The minimum hydrocarbon saturation necessary to initiate primary migration may be reached sooner in layers with relatively high concentrations of organic matter. 

Groundwater overpressure = observed groundwater pressure -hydrostatic groundwater pressure (for Pw = 1020 kg/m3) 

UJ = Upper Jurassic sands MJ = Middle Jurassic sands LJ = Lower Jurassic sands TR = Triassic sands NW = Norwegian well UK = British well 

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The process of migration may lead to focussed movement of hydrocarbons into economic accumulations. The secondary migration of hydrocarbons may occur under hydrostatic or hydrodynamic conditions. Under hydrostatic conditions, the hydrocarbons migrate through the water-saturated carrier-reservoir rocks as separate phase hydrocarbons. Under hydrodynamic conditions, the hydrocarbons may be transported in continuous separate phase, in suspension or in aqueous solution. Under both hydrostatic and hydrodynamic conditions, the hydrocarbons ultimately appear as separate phase hydrocarbons before they can accumulate in a trap (Tissot and Welte, 1984). 

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