Abstract
Carbonate reservoirs are more complex than conventional sandstone rocks. Thisis because most carbonate reservoirs have an additional network of fractures in
the porous media, which results in a highly permeable fracture zone surrounded
by a low permeability matrix, where the rock matrix shows the oil-wet
characteristics. These features make the displacement of oil from the matrix into
the fracture almost impossible during water flooding. To improve recovery
performance through enhancing water imbibition, polymer polyacrylamide
(PAM), and the biopolymer xanthan gum (XG) were used with the aim of
diverting the water into the matrix networks as well as improving the mobility
ratio. Then, the biosurfactant rhamnolipid (RL) was introduced to the system to
modify the wettability state of the rock matrix towards a water-wet state. Three
steps have been taken in this study to improve water imbibition in fractured
carbonate rocks.
The first part of this research was to investigate the impact of the biosurfactant
RL on the wettability states and interfacial activities of carbonate rocks under
reservoir conditions. The results indicated that the biosurfactant RL alters the oilwet
carbonate rocks towards the water-wet state and reduce the interfacial tension
(IFT) at the model’s oil/brine interface.
The second part of the research was to compare and evaluate the efficiency of
using the polymer PAM and biopolymer XG in the presence of polar components
on the rheological properties of water additives and IFT under reservoir
conditions. The obtained results illustrated that the polar components such as
acidic and basic species have a significant influence on the effectiveness of
polymer PAM and biopolymer XG. With respect to the IFT measurements, basic
solutions have been discovered to be less active than acidic solutions in the
reduction of IFT. With regard to the rheological properties point of view, polar
components did not show any effect on the viscosity of the polymeric solutions
at room temperature.
The results from part one and two are put forward to investigate the application
of chemical and biochemical enhanced oil recovery (EOR) methods on the
production of oil in fractured carbonate reservoirs. The results indicate that the
oil recovery levels from oil-wet fractured carbonate cores were 16% and 8.7 %
using the polymer PAM/biosurfactant RL/distilled water and biopolymer
XG/biosurfactant RL/distilled water systems, respectively.
| Date of Award | 1 Apr 2022 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Sina Rezaei Gomari (Supervisor), David Hughes (Supervisor) & Meezanul Islam (Supervisor) |