Geochemical constraints on models for secondary petroleum migration along the upper Devonian Rimbey-Meadowbrook reef trend in central Alberta, Canada

The Upper Devonian Rimbey-Meadowbrook reef trend of central Alberta, Canada , is one of the classical examples that was originally used to support Guss ow's model of differential hydrocarbon entrapment. However, the clear discr epancies,existing between the ideal hydrocarbon distribution predicted by t his model and the one actually observed led to several alternative geologic al models, most of which have not been constrained by organic geochemical d ata. The present study uses a wide range of bulk and molecular parameters t o determine the oil source characteristics and thermal maturity along the r eef trend. The concentrations and isomeric distributions of alkylcarbazoles and non-alkylated benzocarbazoles in oils are employed to study petroleum migration pathways and to constrain the existing secondary petroleum migrat ion models. The data indicates that Gussow's principle is generally applica ble, as the oils in the up-dip direction generally have longer implied migr ation distances although this is not always the case. Other factors not rec ognized previously, such as the presence of two subfamilies of the Duvernay Formation sourced oils, may also have contributed significantly to the dis crepancies in the oil and gas distributions between the model predictions a nd the actual observational data. (C) 1998 Published by Elsevier Science Lt d. All rights reserved.