Source & Trap Volumetrics

Source & Trap volumetrics info pane

The Source and Trap Volumetrics calculation method allows you to enter source-to-trap migration data that may impact the fluid in place. In addition to the Trap Volumetrics parameters the following inputs are available:

  • Fetch Area: The region of source rock that drains toward the prospect.
  • Source Thickness: The average net thickness of source rock within the fetch area.
  • Generation Efficiency: The ability of a source to generate and expel oil.
  • Migration Efficiency: The percent of source-generated oil that could have migrated into the trap due to system plumbing.
  • Trap Timing: The chance that the fetch, trap, and seal were in place at the time of migration.
  • Seal Integrity: The ability of a seal to contain trapped hydrocarbons.

The %POS (probability of success) next to each input indicates the probability that the reservoir is successful in so far as it depends on this input. This only has an effect in a Monte Carlo simulation.

The following equations are used for calculating source and trap volumes:

Generated Oil = 7758 * Generation Efficiency * Source Thickness * Fetch Area

Reservoir Pore Space (Net Pore Volume) = Net Rock Volume * Porosity

Reservoir Gas Volume = Reservoir Pore Space * Gas Cap Volume

Reservoir Oil Volume = (Reservoir Pore Space - Reservoir Gas Volume) * Oil Saturation

Migrated Oil = Generated Oil * Migration Efficiency

Migrated & Trapped Oil = Migrated Oil * Trap Timing

IF Migrated & Trapped Oil < Reservoir Oil Volume

THEN [Possible Trapped Oil = Migrated & Trapped Oil * Seal Integrity]

ELSE [Possible Trapped Oil = Reservoir Oil * Seal Integrity]

Recoverable Oil = Possible Trapped Oil * Recovery Factor / Bo

Solution Gas = Recoverable Oil * Initial GOR

where Initial GOR = initial gas-oil ratio, and Bo = oil formation volume factor; see Oil (Fluids).

As can be seen from the equation, Fetch Area, Source Thickness, Generation Efficiency, Migration Efficiency and Trap Timing will have an impact on reserves calculation only when Migrated & Trapped Oil is lower than Reservoir Pore Space.