Liu, Keyu1, Peter Eadington1
(1) CSIRO Petroleum, Bentley, WA, Australia
ABSTRACT: New Quantitative Fluorescence Techniques for Reconstructing Hydrocarbon Charge History
Under reservoir conditions hydrocarbons may be trapped in reservoir grains as inclusions by diagenetic cementation or adsorbed onto the grains via physical and chemical bonding. These hydrocarbon fingerprints provide critical information for the reconstruction of hydrocarbon charge history.
We have developed two patented fluorescence techniques called Quantitative Grain Fluorescence (QGF) and Quantitative Grain Fluorescence on Extract (QGF-E) that can be used to detect palaeo oil zones and current residual oil zones in petroleum wells, respectively. The techniques measure the UV-Vis emission spectra of trace fluorescence from reservoir grains and their extracts using a sensitive spectrophotometer. QGF is measured on dry, disaggregated reservoir grains after a cleaning procedure involving solvent, hydrogen peroxide and acid, whereas QGF-E is measured on the solvent extract from the QGF cleaned grains.
The methods have been tested on petroleum wells from Australia and SE Asia on known current and palaeo-oil zones and have been calibrated with other analytical techniques including petrographic counting of oil inclusions, total n-alkane yields of crushed oil inclusions, mass spectrometry determined oil inclusion abundances, wireline log, well testing and extraction data.
Palaeo oil zones have distinct QGF spectra with spectral peaks between 375 and 475 nm and elevated fluorescence intensities compared with spectra for rocks that have always been water saturated. Current and residual oil zones have distinct QGF-E spectra with spectral peaks at around 370 nm and elevated QGF-E intensities compared with that for current water zones. Both QGF and QGF-E intensities increase upwards from the current and palaeo OWCs, respectively.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.