Structural Similarities Between Oil-Generating Kerogens and Petroleum Asphaltenes

Abstract

Abstract Evidence from spectrometric and degradative analyses suggests that oil-generating portions of kerogens and petroleum asphaltenes may have very similar structures, consisting dominantly of fused-ring cycloalkanes. A model for these macro-molecular structures is proposed, and a mechanism is suggested by which both cyclic and straight-chain hydrocarbons may be produced by diermal breakdown of saturated fused-cyclic systems. This model and the proposed mechanism have important implications for petroleum generation and expulsion. Asphaltenes may be fragments of the original kerogen from which crude oil is derived and may be expelled as part of the crude oil. If so, asphaltenes set a lower limit for the size of openings in source rocks through which oil must be expelled. This interpretation also indicates that asphaltenes may be very useful for regenerating normal"oil" from a bacterially degraded oil for purposes of correlation.