Environmental Engineering Reference
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electrodes, and ion exchange resin packs were used at the two ends of each
cell. The cells were designed in a manner that minimized transport of pH
fronts into the cores and they were hydraulically balanced to reduce flow
through the cores. Liquid and solid samples were retrieved through the
ports placed on the cell walls. Three different crude oils representing a
wide range of dynamic viscosity, but the same brine solution was used
in preparation of the cores. The physical properties of the fluids used are
presented in Table 2.5. The composition of the surrogate formation cores
was 52% sand (mean particle size 0.23 mm), 40% silt (mean particle size
0.025 mm), and 8% Georgia Kaolinite clay (mean particle size 0.0011mm).
The initial porosity, water, and oil saturation were determined to be 30%,
46%, and 48%, respectively. The representative synthetic core permeability
was measured as 510mD.
The viscosity of the oil specimens extracted from 107-day forma-
tion samples treated under applied current density of 1 Amp/m 2 showed
a significant drop in all regions compared to their control value for the
Pennsylvania and Canadian oils, as shown in Figures 2.45 and 2.46. For
the Pennsylvania oil sample, the viscosity dropped by 35% in the anode
region, 23% in the middle region, and about 13% in the cathode section.
For the Canadian oil sample, the viscosity at the anode region dropped by
69% and by 26% in the cathode region.
The post-test SARA analysis (i.e., measures the contents of saturates,
asphaltenes, resins and aromatics in oil) of the California and Canadian oil
samples are shown in Figures 2.47 and 2.48. In concert with its post-EK
Table 2.5 Physical properties of the formation oils and water
Fluid
Properties
PA field oil
API 47; Dynamic viscosity = 38.7 cP
Specific gravity =0.79 at 20°C
CA field oil
API 17.4; Dynamic viscosity = 2782 cP
Specific gravity =0.95 at 20°C
Canadian field oil
API 13; Dynamic viscosity = 52000 cP
Specific gravity =0.98 at 20°C
Electrolyte solution
(Surrogate forma-
tion water)
Salinity= 33,000 ppm; Electrical conductivity
= 45,000 μS
pH = 7.50; Major elements: Na, Cl, Mg, S, K, Ca, Br
 
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