ABSTRACT

Surface geochemical detection of deeply seated hydrocarbons is an inexact science. It has been firmly established that there is upward movement of chemical compounds from hydrocarbon reservoirs. Therefore the challenge is to develop economical methods to assist in differentiating those seismic anomalies that represent barren structures from those that host hydrocarbons.

The recently developed enzyme leach method of extracting elements loosely bound to amorphous manganese oxide coatings on soil particles has been tested in southeastern Saskatchewan. The target, an Ordovician Red River reservoir at a depth of 2850 m, was studied by collecting soil samples from 74 sites within a one square mile (2.6 km2) section. A 3-D seismic structure that is quite pronounced at the Ordovician Winnipeg - Red River formation level is outlined by a number of element enrichments in the soils that flank its surface projection. Of note are relative enrichments of the halogens (Br, I, CI) and of Mo, Re, W, V, As and Sb. Copper, Ni, Ba, Cd, Sr and U also show positive but less distinctive relationships to the structure.