Print this pageInsights on the Effect of Phase Separation on the Alkylphenol Composition of Petroleum During Migration – a Pressure-Volume-Temperature (PVT) Experimental Approach
Sandra Ortega-Lucach1, Thomas B. P. Oldenburg2,
Steve R. Larter2, Bernard F. J. Bowler3, Brian
Moffatt4, and Ed Clarke4
1 Instituto Mexicano del Petróleo, Mexico-City, Mexico
2 University of Calgary, Calgary, AB
3 University of Newcastle upon Tyne, Newcastle upon Tyne,
United Kingdom
4 BP group, Reading, United Kingdom
The main aim of this study was to examine the effects of phase separation-migration related processes on the distribution of alkylphenols between liquid and gas phases. Based on the similarity between the pressure-temperature (PT) reduction process during petroleum migration and the PT reduction process which occurs during reservoir engineering laboratory pressure-volume-temperature (PVT) tests, we have therefore used a PVT experimental approach to simulate the physical and chemical changes that petroleum undergo during phase separation-migration. Results indicate that in addition to the well known effects on the relative concentrations of light aliphatic and aromatic hydrocarbon compounds, the physical partitioning of petroleum components between the gas and the liquid phase in equilibrium in petroleum reservoirs can affect even “high molecular weight” compounds, such as alkylphenols. For example, there is a steady increase in alkylphenol concentrations in the liquid phase with decreasing PT conditions whereas their concentrations decrease in the gas phase during the PVT tests performed. A general increase in the preferential partitioning of lower alkylated homologues into the gas phase compared to higher alkylated homologues with decreasing PT conditions was observed. Similarly, there was preferential partitioning of lower boiling point isomers into the gas phase compared to higher boiling point isomers. The results also indicate that the migration history (e.g. the frequency and extent of multiple equilibrations between the gas and liquid phases in a reservoir, and the release of the fluid phases during fill-spill migration) is an important factor to be included in the geochemical interpretation of petroleums.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005