Light and condensable oils derived from mature kerogen and residual oil in deep source rocks have contributed strongly to a rapid increase in oil production. In this study, oil expulsion from kerogen and shale was simulated by selective solvent extraction (hexane/toluene, 9:1 v/v, instead of the commonly used dichloromethane) and by returning the extracts (so-called "oil a") back into a controlled mass of mature kerogen. The maturity intervals and potential of the light oil and condensates were investigated by analyzing the yields of different hydrocarbons from the subsequent pyrolysis of mature kerogen-"oil a" mixtures. The gas-to-oil ratio was used to constrain the maturity range for the light oil, condensate, and gas stages. The lowest equivalent vitrinite reflectance (EVRo, 1.9-2.1%) for the gas stage was compatible with commonly accepted models. The EVRo cutoff of 1.55-1.75% between light oil and condensate was higher than that in traditional models, although this depended primarily on the generality of the "condensate" definition. An EVRo ranging between 1.35 and 1.55-1.75% was defined in this work as the "light oil/gas" substage within the commonly accepted condensate/wet gas stage. Moreover, yields of hydrocarbons from the cracking of "oil a" were distinctly affected by mature kerogen. This effect showed little difference on the yield of C6-14 hydrocarbons and C15+ hydrocarbons but notable difference for the gases between types I and II kerogens. The release of C6-14 hydrocarbons was promoted when the release of C15+ hydrocarbons was notably inhibited. Approximately linear relationships were established between maximum yields of liquid hydrocarbons and the carbon content of "oil a" (selective solvent extraction products) in the mixtures. This relationship was helpful in estimating both oil and total petroleum potential of deep source rocks that have undergone oil generation and expulsion, but it was dependent on the composition of the solvents used in extraction.