Petroleum generation by laboratory-scale pyrolysis over six years simulating conditions in a subsiding basin

Abstract

Many researchers have attempted to duplicate under laboratory conditions the geochemicäl reactions that lead to economic deposits of liquid and gaseous hydrocarbons^1–4. Experiments lasting from a few^5,6 to several hundred⁷ days, usually at constant temperatures, have been devised. The differences in time scale and other parameters between geological processes and laboratory experiments are so great that the relevance of labora tory results is often questioned^8,9. Consequently, we have heated potential source material from 100 to 400 °C over six years, increasing the temperature by 1 °C per week. This was done in an attempt to simulate the thermal history of a sample being buried in a continuously subsiding basin with a constant geothermal gradient. After four years, a product indistinguish able from a paraffinic crude oil was generated from a torbanite, while a brown coal gave a product distribution that could be related to a wet natural gas. Of great significance is the absence of olefins and carbon monoxide in all products. We believe the present experiments, which are possibly as slow as can be realistically planned within a human time scale, have for the first time successfully duplicated hydrocarbon generation in a continuously subsiding sedimentary basin.