Evaluation of a petroleum prospect requires the geologist to estimate the amount of hydrocarbons and the composition (GOR) expelled from the source rock. Current understanding stipulates that the quantity and GOR of petroleum ultimately expellable from a source rock can be determined from simple source rock parameters such as those measured in a Rock-Eval experiment.

This Applet calculates the hydrocarbon expulsion potential of a source rock based on basic rock-Eval parameters. The outputs are ultimate expellable hydrocarbons from the source rock. The amount of gas versus oil expelled are based on published relationships of source data (i.e. Pepper and Corvi, 1995). The results can be used to constrain charge volumes and GOR. More sophisticated volumetric modeling can be done with KinEx to include the effects of heating rate and facies variations. Lateral geological variability and migration can be account for in Trinity . Trinity can also be used to quantify the volumes probabilistically. But, hey, this one is free (no guarantees of any kind)!

1. All volumes are STP (surface) conditions. mmbls = million barrels and bcf = billion cubic feet.
2. Multiply the area to the result to obtain total potential over an area.
3. Divide the number by 247 to get volumes per acre (1 km² = 247.1044 acres).
4. Rock density is variable, as higher TOC rocks should have lower densities.
5. This model is actually more sophisticated than just mass balance considerations. It also accounts for variability in GOR and oil API gravity, etc.

• Pepper, A. S., and P. J. Corvi, 1995, Simple kinetic models of petroleum formation. Part I: oil and gas generation from kerogen : Marine and Petroleum Geology, v. 12, pp.291-319.
• Pepper, A. S., and P. J. Corvi, 1995, Simple kinetic models of petroleum formation. Part III: Modeling an open system : Marine and Petroleum Geology, v. 12, n. 4 pp.417-452.