Abstract: V/Ni Ratio in Crude Oil Fractions from the West Venezuelan Basin: Correlation Studies
S. Lo Monaco, L. Lopez, A. Rojas, A. Lira
This study presents the analyses of S and the metals Cr, Zn, Fe, Mn, Cu, Co, Ni, Mo, V and Sr within the fractions of saturated hydrocarbons, aromatic hydrocarbons and resins, and the IR spectroscopy analysis of these fractions for crudes of the Mara and Mara Oeste fields of the Maracaibo basin.
These results are discussed as related to their implications in oil-oil correlation, and studies of the possible metal-organic associations, and are compared with previous studies which analyzed S, V, and Ni in the total crude and its asphaltene and maltene fractions. In the saturated fraction, elements Zn, Fe, Mn, Cu, Ni and Sr were detected. In the aromatic fraction, in addition to the before mentioned elements, Cr and Ni were also detected; while in the resins elements Cr, Zn, Fe, Cu, Ni, Mo, V and Sr were detected. S was detected in the three fractions studied, and IR spectra show bands that may be related to organic compounds that contain S. IR results for the aromatic hydrocarbons and the resins indicate the presence of carboxylic groups which can serve as ligands for metals in uch fractions. The larger number of elements detected within resins, as well as their higher concentration vs. saturated and aromatic hydrocarbons, may be due to the structure of the resins and their greater ability to form organometallic complexes.
The relatively constant V/Ni ratios in crudes (11 +/-1), maltene (15 +/-1), asphaltenes (15 +/-1) and resins (11 +/-1) give support to a single group of crudes. These results indicate that the V/Ni ratio determined for the whole crude or its fractions may be used as a correlation parameter.
AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela