Jennifer Jane Adams

Methods for recovery of microorganisms and intact microbial polar lipids from oil-water mixtures: laboratory experiments and natural well-head fluids.

Most of the worlds remaining petroleum resource has been altered by in-reservoir biodegradation which adversely impacts oil quality and production, ultimately making heavy oil. Analysis of the microorganisms in produced reservoir fluid samples is a route to characterization of subsurface biomes and a better understanding of the resident and living microorganisms in petroleum reservoirs. The major challenges of sample contamination with surface biota, low abundances of microorganisms in subsurface samples, and viscous emulsions produced from biodegraded heavy oil reservoirs are addressed here in a new analytical method for intact polar lipids (IPL) as taxonomic indicators in petroleum reservoirs. We have evaluated the extent to which microbial cells are removed from the free water phase during reservoir fluid phase separation by analysis of model reservoir fluids spiked with microbial cells and have used the resultant methodologies to analyze natural well-head fluids from the Western Canada Sedimentary Basin (WCSB). Analysis of intact polar membrane lipids of microorganisms using liquid chromatography-mass spectrometry (LC-MS) techniques revealed that more than half of the total number of microorganisms can be recovered from oil-water mixtures. A newly developed oil/water separator allowed for filtering of large volumes of water quickly while in the field, which reduced the chances of contamination and alterations to the composition of the subsurface microbial community after sample collection. This method makes the analysis of IPLs (or indirectly microorganisms) from well-head fluids collected in remote field settings possible and reliable. To the best of our knowledge this is the first time that IPLs have been detected in well-head oil-water mixtures.

Viscosity and API Gravity Determination of Solvent Extracted Heavy Oil and Bitumen

This paper describes and discusses laboratory experiments showing that reliable determinations of viscosity usually cannot be made on high viscosity samples of heavy oil or tar sand bitumen that have been solvent extracted from core or cuttings samples with toluene or otherwise contaminated or diluted with this solvent. The toluene solvent cannot be quantitatively removed without damaging the bitumen sample because of the concomitant evaporation of volatile materials that act as natural solvents in the bitumen. Only small amounts of natural or contaminant solvent are sufficient to effectively control the sample viscosity. Viscosity values determined on residual bitumen after solvent removal may be either lower or higher than the nominally correct value depending on whether excessive residual toluene solvent remains in the sample or excessive volatile material has been removed from the sample during the evaporation. On the other hand, the impact of solvent on the density (i.e., API gravity) of a sample is linear and there are several advantages to using solvent plus bitumen mixtures to determine density for high viscosity samples.