Investigated Miscible CO2 Flooding for Enhancing Oil Recovery in Wettability Altered Chalk and Sandstone Rocks
Doctoral thesis
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http://hdl.handle.net/11250/183677Utgivelsesdato
2012-05-29Metadata
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- PhD theses (TN-IPT) [21]
Originalversjon
Investigated Miscible CO2 Flooding for Enhancing Oil Recovery in Wettability Altered Chalk and Sandstone Rocks by Vahid Alipour Tabrizy, Stavanger : University of Stavanger, 2012 (PhD thesis UiS, no. 162)Sammendrag
The thesis addresses oil recovery by miscible CO2 flooding from modified
sandstone and chalk rocks. Calcite mineral surface is modified with stearic
acid (SA) and asphaltene, and the silicate mineral surfaces are modified with
N,N-dimethyldodecylamine (NN-DMDA) and asphaltene. The stability of
adsorbed polar components in presence of SO4
2- and Mg2 + ions is also
investigated.
Recovery from sandstone cores is consistently lower than that from chalk
cores saturated with the same oil and flooded with CO2 at all miscible flooding
conditions. This may be due to the larger permeability contrasts in sandstone
cores, which promote the fingering phenomenon. Miscible CO2 flooding for
chalk and sandstone cores with distilled water, as initial water saturation,
shows also lower oil recovery than cores saturated with different ions.
At higher miscible flooding conditions, higher oil recovery is obtained.
However, presence of light components (such as C1 or C3) in oil reduced the
recovery. Oil recovery in presence of methane (C1) is lower than that in
presence of methane and propane (C1/C3). A ternary diagram was constructed
in order to understand the CO2 flooding mechanism(s) at the different
flooding conditions and in presence of light components.
The side effect of the flooding with CO2 is the probability for asphaltene
deposition. An approach based on solubility parameter in the liquid, is used to
assess the risk for asphaltene deposition during CO2 miscible flooding. The
light components (C1/C3) and higher flooding conditions enhanced the risk for
asphaltene instability. It is also shown higher amount of asphaltene deposition
in chalk cores than that in sandstone cores at similar miscibility conditions.