Hydrogeological Influences on Petroleum Accumulation in Red Earth Region, North-Central Alberta, Canada

Daniel Barson, Jozsef Toth

In the Red Earth region of Alberta, economic light oil pools occur in mid-Devonian strata. Potentiometric surface maps for the reservoir formations show that these accumulations are concentrated in or near potentiometric depressions with minor lateral hydraulic gradients. Bitumen deposits in the lowermost Cretaceous at the sub-Cretaceous unconformity are also clearly associated with laterally and vertically converging fluid flow.

A preliminary analysis of the distributions of temperature and total dissolved solids indicates that the oil field waters are significantly warmer and of higher salinity than adjacent nonpetroliferous waters. A genetic connection between the distribution patterns of these distinct phenomena is provided by the unifying framework of the hydraulic theory of petroleum migration.

The theory postulates that in geologically mature sedimentary basins, gravity-induced cross-formational flow of fluids controls the transport and accumulation of petroleum. Hydrocarbons move along well-defined paths toward the discharge zones of converging flow systems. Accumulations occur en route against suitable permeability filters in hydraulic or hydrodynamic traps. Oil and gas pools that formed in energetically stagnant zones and along the discharge limbs of flow systems are therefore characterized by potentiometric minima, increasing hydraulic heads downward and minor lateral hydraulic gradients. Forced convective heat input and long residence times may create higher than background heat flow and high water salinity.

Once the theory is proved to account for the above mentioned conditions, it may then be used as a basis for systematic petroleum exploration.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.