EXPERIMENTAL SIMULATION OF OIL MIGRATION - DISTRIBUTION EFFECTS ON ORGANIC-COMPOUND GROUPS AND ON METAL-METAL RATIOS

A laboratory experiment was set up to determine the distribution effec ts in a heavy oil migrating through a 104-m-long column packed with wa ter-wet 20-60-mum particles of glacimarine silt. The oil was pumped th rough the column at 100-degrees-C, with a backpressure of 400 bar, col lected in small fractions at the outlet, and the distribution of satur ates, aromatics and polars in each fraction was determined. After prep arative class fractionation, the fractions were analyzed by gas chroma tography, -mass spectrometry (GC-MS), -atomic emission detection (GC-A ED) and with inductively coupled plasma-mass spectrometry (ICP-MS). In the oil front, the amount of volatile hydrocarbons, mainly below C10- 12, were lowered compared to the later eluting fractions, due to water -washing. The amounts of sulfur-containing compounds in a polar fracti on were affected by migration, but the composition of hydrocarbons was in general little influenced by the migration. The concentrations of several metals in the migrated oil were reduced compared to the levels in the not-migrated oil. In contrast, some elements, particularly Cu and Mn, were extracted from the column into the migrating oil. Class f ractionation was essential to obtaining a view into different migratio n effects for several metals. In the asphaltenes class, the migration had little effect on the Ni/V, Co/V and Mo/(Mo + Cr) ratios which are used in oil-oil and oil-source rock correlations. In other classes sev eral metals were distributed unevenly in the migration fractions, most likely due to different migration effects. Ni and V were the metals l east affected by the migration process. Correlation factor calculation and factor analysis were performed to improve the quality of the anal ytical data and to control the consistency of the main conclusions.