An X-ray CT study of multidimensional imbibition in dual porosity carbonates
Abstract/Contents
- Abstract
- Recovering oil from fractured systems is very challenging. Implementing a waterflood recovers oil in the fractures but not much of the oil in the matrix. To mitigate low recovery, one option is to increase the viscosity of the injected water using polymers or foam. This work investigates another option that involves injecting surfactant solutions. Surfactants reduce interfacial tension (IFT) and consequently capillary forces that are responsible for trapping oil within the matrix. Our claim is that if capillary forces are low enough, gravity lifts the oil by buoyancy towards the fracture network then to the producers. To investigate this claim, core-flood experiments are conducted vertically to account for gravity forces. A horizontal experiment, however, is initially performed to allow for evaluating the improvement of oil recovery when the experiments are conducted vertically. All experiments are monitored by X-ray computed tomography (CT) scanning to quantify fluid saturations and monitor front movements. There are two phases for each experiment: a saturation phase and an imbibition phase. In the saturation phase, the core is confined by a core sleeve and initial oil and water saturations are obtained. The confining pressure is released, in the imbibition phase, allowing for a fracture-like space between the core and the sleeve. Injected fluids now selectively channel through the fractures towards the outlet and oil recovery from the matrix becomes mainly governed by spontaneous imbibition. Both phases need to be performed in one core holder to minimize positioning errors while X-ray CT scanning. Therefore, a novel core holder was designed and fabricated that allows for saturating the core and then conducting the imbibition experiment. Two types of carbonate cores were used: Texas cream from an outcrop and oil field cores. For the oil phase, decane was initially used for to focus the study on fluid-fluid interactions and crude oil was later used for other experiments to account for fluid-fluid interactions and rock-fluid interactions. Experiments show that gravity has the potential to improve oil recovery when IFT is reduced. Even for small reduction of IFT, recovery factor (RF) increased by more than 4% of original oil in place (OOIP) when the experiments were conducted vertically. Moreover, the surfactant flood mode was found to impact the ultimate RF. The ultimate recovery factor (URF) for a secondary surfactant flood was greater by about 7% of OOIP than a tertiary surfactant flood.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2013 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Alshehri, Amar Jaber |
|---|---|
| Associated with | Stanford University, Department of Energy Resources Engineering. |
| Primary advisor | Kovscek, Anthony R. (Anthony Robert) |
| Thesis advisor | Kovscek, Anthony R. (Anthony Robert) |
| Thesis advisor | Castanier, Louis M |
| Thesis advisor | Horne, Roland N |
| Advisor | Castanier, Louis M |
| Advisor | Horne, Roland N |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Amar Jaber Alshehri. |
|---|---|
| Note | Submitted to the Department of Energy Resources Engineering. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2013. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2013 by Amar Jaber M. Alshehri
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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