SHELF AND SHELLOW BASIN OIL AS RELATED TO HOT‐DEEP ORIGIN OF PETROLEUM

Abstract

Oil and gas pools in shallow basins of on the shallow, stable shevles of deeper sedimentary basins appear to be exceptions to the model of a hot‐deep origin of petroleum. However, the oil in shallow basins is directly associated with faulting extending out of the deepest parts of the basin. Evidence exists that some of these shallow basins have been much hotter in the past either from igneous activity of from a higher geothermal gradient. Uplift and erosion may also have removed substantial thicknesses of sediments in some of these basins. Oil on the stable, shallow, shelvees of deep basins could originated in the deeper part of the basin and undergone long lateral migration to the traps where it is now found. Conduits for such migration could have been sandstones in delta‐distributary systems (E Oklahoma and Kansas), reef trends (Alberta, Canada), or regional porosity and permeability in sheet carbonates (Anadarko basin. W. Oklahoma and Kansas). The model discussed herein allows us to (1) predict which areas of the stable shelves of deep basins should produce hydrocarbons and which areas should not, (2) predict the type of hydrocarbon (gas or oil), (3) set the limit of lateral updip migration, of hydrocarbons within any one formation in a basin, and (4) predict the downdip occurrence of hydrocarbons in the formation. The model should aslo help us determine which shallow cratonic basins should produce oil and which should not.