问答题 翻译：crude petroleum is not an equilibrium mixture, and on a geological time scale its composition is slowly changing. S.R.silverman found that heating at 121C for two weeks caused detectable changes, the low-molecular-weight components formed being isotopically lighter so far as the carbon was concerned, than the original.
问答题 翻译：A third means of assessing the maturity of rocks is by the pyrolysis of a small amount of the source rock. The temperature is raised rapidly and the material vaporized or formed by thermal breakdown of the kerogen is passed through a detector which records, on a temperature base, peaks representing these two bursts of volatile material. To a first approximation the peak at the lower temperature represents oil already generated; the peak at the higher temperature indicates oil capable of being generated at adequate maturity.
问答题 翻译：A paraffin base crude is an oil whose chief components are paraffins, and which completely distilled, leaves a solid residue of wax. An asphalt base crude is an oil composed primarily of cyclic compounds (mostly naphthenes) which, when distilled, leaves a solid residue of asphalt. Oils which fall in the middle of these categrories are classified as mixed base.