Crude-Oil Correlations and Their Role in Exploration

摘要: Sufficient parameters for most petroleum correlations are provided by correlation indexes, which measure the relative amounts of paraffins, naphthenes, and aromatics in each distillation fraction, sulfur nitrogen contents oils. Such data available from United States Bureau Mines several thousand crude oils, they provide a chemical profile entire petroleum. Correlation indexes similar to computed ratios hydrocarbons derived more detailed analytical methods. There geological examples scientific reasons not agreement with Barton's concept maturation petroleums aromatic paraffinic oils increasing age burial depth, although A.P.I. gravities were found increase content decrease depth accordance hypothesis. Mild subsurface thermal cracking can explain decrease, because residuum undergoes conversion mostly gases only small light liquids being formed. could cause gravity while index character remains almost unchanged. However, extensively cracked deep-seated may be changed greatly. Geological exist inconsistent hypothesis that ligno-humic compounds terrestrial sources principal suppliers petroleums. Lacking any reasonably large quantities both naturally occurring writer concludes these cyclic formed other materials, likely straight-carbon-chain lipids. The dehydrogenase activity anaerobic bacteria appears important mechanism creation aromatics, asphaltenes lipids, judging examples. Anaerobic bacterial source sediments related degree aeration, it is reflected mineralogically. Examples show crudes oxidized sediments, aromatic-asphaltic euxinic naphthenic intermediate character. Nitrogen believed have been solely nitrogenous proteins amino acids. High empirically high phosphate rocks. This consistent Emery's observations Recent regeneration parallels regeneration. analyses an independent parameter directly oxidation-reduction state environment. Inspissation through leakage or surface seepage alteration some shallow accumulations. Paraffins appear selectively removed as expelled, accord principle homology. Thus decreases. Components relatively unaffected, result between components such remain essentially do caused significant changes after expelled rocks, except where come direct contact deposits sulfate minerals. effects selective filtration, adsorption, water "washing" on certain small. Therefore, shallow, inspissated deep, thermally altered distillates, free post-diagenetic change. Several fields Wyoming, Utah, Colorado illustrations use oil identify parent rocks detect cross-formational migration. Correlations make possible determine whether formations their own indigenous source, permit recognition major oil. lead conclusion Permo-Pennsylvanian Minnelusa reservoirs eastern Wyoming Permian Phosphoria western thus requiring regional pre-Laramide, Mesozoic, migration occurred. Exceptionally low gas saturations original Phosphoria-source preclude application Gussow's differential entrapment this case. Mesozoic Tensleep assist tracing favored areas traps.