The goal of this project was to improve recovery of Alaskan North Slope (ANS) heavy oil resources in the Ugnu formation by improving our understanding of the formation's vertical and lateral heterogeneities via fluid and rock characterization. Although the reserves of heavy oil on the North Slope of Alaska are enormous (estimates are up to 10 billion barrels in place), difficult technical and economic hurdles must be overcome to produce them. The Ugnu formation contains the most viscous, biodegraded oils and standard production methods are ineffective.
Heavy oils are viscoelastic fluids. Thus, it is critical that we understand the properties of the heavy oils we are trying to produce before the geophysical model and modeling plan can be completed. The Ugnu oils (including more than 18 oil, oil/sand, oil/water, and oil/sand/water mixtures) exhibited non-Newtonian characteristics, including shear thinning and a non-zero shear modulus. The complex viscosity of the dead oils has been found to be as high as 7,000 Pa's and a shear modulus at −10°C above 10,000 Pa (and frequency dependent). A complete set of " live" oil rheology experiments were completed. A large range of temperatures (−10 to 60°C) and pressures (15 to 2000 psi) were controlled and viscosity measured in novel high-pressure rheology setup.
Saturate-Aromatic-Resin-Asphaltene (SARA) fractions have been measured on site and by an outside laboratory. The SARA technique has large experimental variation when used to measure heavy oils. Asphaltene content varied from 3 to 9% in the same sample measured by CSM and an outside laboratory. A large number of experiments have been completed, including molecular beam mass spectroscopy (MBMS), optical and scanning electron microscopy, and other techniques not reported here. Chemistry signatures from the MBMS and SARA have been correlated with the viscosity of the heavy oils.