29 Undergraduate Research (Posters)

Thursday, 12 April 2007
1:40 PM - 5:00 PM

THERMAL BEHAVIOR OF HYDROCARBON-BEARING ROCKS DETERMINED BY SIMULTANEOUS THERMAL ANALYSIS/QUADRUPOLE MASS SPECTROMETRY

Paper number: 29-27
Program: THEME SESSIONS
Time: 1:40 PM – 5:00 PM

Authors

Abstract

Hydrocarbon-bearing shale and limestone samples were analyzed by Simultaneous Thermal Analysis/Quadrupole Mass Spectrometry, which combines calorimetry, thermogravimetry, and evolved gas analysis. This technique has not seen wide use in the geosciences; however, results of this study demonstrate its great potential in the characterization of a wide range of geological materials. The instrument design (ours was manufactured by Netzsch, GmbH) involves a skimmer coupling that allows direct sampling of gases from the sample surface and prevents their condensation, a problem that is commonly observed in systems utilizing transfer lines. Samples were heated at a constant rate (from 25 to 1100 °C) in a helium atmosphere. An array of phase transitions was observed that were accompanied by mass loss, exothermic/endothermic reactions, and/or evolution of volatiles.

Limestone samples exhibit different mass losses, with most of the mass lost at temperatures greater than 650 °C. This mass loss corresponds to endothermic reactions, and the evolution of CO2, N2, and CH4. Shale samples experienced total mass losses ranging from 17% to 45%. The wide range in total mass loss between samples is probably a reflection of different clay contents. The shales exhibit different gas release patterns and temperatures, but all of them released H2O, CO2, N2, CH4, C2H6, and SO2.

This study illustrates the usefulness of this method for the analysis of hydrocarbon-bearing rocks. This technique could be applied to characterize the behavior of rocks subjected to enhanced thermal recovery methods.