Composite diagram of fluoresce spectrophotometer, quartz grains under visible and ultraviolet light and the spectra recorded

The QGF and QGF-E instrumentation and what is measured

QGF and QGF-E

We apply the QGF (Quantitative Grain Fluorescence) and QGF-E (Quantitative Grain Fluorescence on Extract Fluorescence) techniques for the petroleum industry.

  • 12 October 2009 | Updated 14 October 2011

Introduction

Quantitative Grain Fluorescence (QGF) and Quantitative Grain Fluorescence on Extract Fluorescence (QGF-E) are techniques for detecting current and palaeo-oil zones by measuring the intensity of fluorescence from ultraviolet light-excited hydrocarbons sealed in fluid inclusions and at the surface of siliciclastic rocks.

Advantages

QGF and QGF-E are rapid screening techniques that:

  • provide information on both current day and paleo-oil saturation in a reservoir during a single analytical procedure
  • provide both UV and visible spectral information
  • have short turn-around times
  • are low cost.

Uses

CSIRO uses QGF and QGF-E to investigate oil migration and petroleum charge history using core and cutting samples from petroleum exploration wells. The technique is most valuable when there are a number of closely spaced samples across the reservoir interval of interest.

Uses of QGF-E (siliclastics and carbonates) include:

  • detecting current oil zones where oil-based drilling muds have been used or where there are indeterminate oil shows
  • delineating oil-water contacts.

Uses of QGF (siliclastics) include:

  • detecting palaeo-oil zones 
  • delineating palaeo oil-water contact.

Background and technical information

QGF is only suitable for clastic reservoirs, whereas QGF-E can be applied to investigate both clastic and carbonate reservoirs.

The techniques use standardised sample preparation methods and analytical procedures.

The fluorescence intensity signal from a given amount of reservoir grains or extract is proportional to the amount of oil (included and absorbed or extracted, dependant upon technique used) and gives an approximate relative current or palaeo-oil saturation in the reservoir.

QGF and QGF-E can be applied to investigate oil migration and petroleum charge history.

QGF and QGF-E can be applied to investigate oil migration and petroleum charge history.

The QGF and QGF-E spectra for oil zones and water zones have distinct features and can be used to eliminate anomalous mineral fluorescence; different oils have different QGF and QGF-E spectra.

During the interpretation of results an empirical database containing known oil zone and water zone samples is referenced and where possible local baseline values for QGF and QGF-E and their spectral signatures are established.

Read about how CSIRO's technologies are providing innovative solutions to improve petroleum exploration[external link]