Alternative indicators to assess the distribution characteristics of methane, ethane, and propane derived from petroleum in the Montney Formation, Western Canada

Understanding fluid distribution within the most prolific low-permeability hydrocarbon reservoir of the Western Canadian Sedimentary Basin (WCSB), the Montney Formation, continues to be a challenge due to the complex history of hydrocarbon migration, which includes thermal alteration of hydrocarbons that migrated before maximum burial as well as more recent migration due to uplifting in the Eocene. In this study, we have assessed the occurrence of methane, ethane, and propane using parameters that are based on the possibility of molecular interconversion between C1-C3 alkanes. This approach allowed us to identify the boundary between two hydrocarbon plays within the Montney Formation based on the composition coefficient Q, and the compositional factors (C2H6)2 and (CH4).(C3H8), which are less susceptible to methane migration [particularly (C2H6)2]. One play is located primarily in Alberta and includes unconventional and conventional hydrocarbon fields; the second play is located exclusively in British Columbia and consists of unconventional hydrocarbon fields. Our new approach enables the identification of main hydrocarbon migration zones within conventional and unconventional sections (e.g. northeast, southeast, and central-west). Additionally, we used the C2/C3 ratio as a maturity indicator in the Montney Formation, which facilitates the identification of overpressure zones (to the southwest) and target areas for natural gas liquids (NGL) production (based on an estimated 1.5 %Ro). The assessment we have conducted can be further explored in other low-permeability hydrocarbon reservoirs.

Automated summary

This study assessed the occurrence of methane, ethane, and propane in the Montney Formation using parameters based on molecular interconversion between C1-C3 alkanes, which helped identify boundaries between hydrocarbon plays, migration zones, maturity indicators, and target areas for natural gas liquids production. The approach used in this study can be further explored in other low-permeability hydrocarbon reservoirs.