ZABERI, HUSAIN
(2017)
Core Flooding Study of CO2-Soluble Polymers for Improved Mobility Control and Conformance Control.
Master's Thesis, University of Pittsburgh.
(Unpublished)
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Abstract
Despite its success in recovering oil as an enhanced oil recovery (EOR) solvent over the past 50 years, the effectiveness of CO2 is hindered by its low viscosity relative to the oil and water being displaced. This results in an unfavorable mobility ratio that promotes viscous fingering and gravity override, thereby reducing oil recovery. The initial focus of the research was to decrease CO2 mobility through a long-term injection of a dilute solution of a high molecular weight polyfluoroacrylate (PFA) thickener in CO2 capable of quadrupling the viscosity of CO2. However, when thickened CO2 was used to displace pure CO2 from sandstone or limestone cores at a constant volumetric flow rate, the pressure drop increased by factors significantly greater than four. Coupled with increased hydrophobicity of the core and the recovery of polymer downstream of the core, it became apparent that some of the polymer remained dissolved in CO2 solution and passed through the core as desired, but some of the PFA adsorbed onto the core surfaces and dramatically reduced permeability while enhancing hydrophobicity. Therefore, the notion of using PFA as a CO2 mobility control agent that remains dissolved in CO2 solution while propagating hundreds of feet from an injection well without suffering adsorption loss was deemed unrealistic. However, the PFA-induced permeability reduction makes PFA an excellent candidate as the first CO2-soluble conformance control agent. During conformance control, the intent is to inject a small slug of (CO2+PFA) solution into the near-wellbore region of a high permeability, watered-out, oil-depleted thief zone, especially if the zone can be temporarily isolated during injection of the PFA solution. If the PFA solution is successful in reducing the permeability of the thief zone, subsequent injection of CO2 into all zones should result in a much smaller proportion of the CO2 going into the thief zone and a larger proportion of the CO2 entering the oil-rich zones. Numerous CO2-displacing-brine core flooding tests were then conducted to test this hypothesis and conformance control was often achieved with (CO2+PFA) solutions, especially in parallel sandstone cores.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
1 February 2017 |
| Date Type: |
Publication |
| Defense Date: |
17 November 2016 |
| Approval Date: |
1 February 2017 |
| Submission Date: |
18 November 2016 |
| Access Restriction: |
2 year -- Restrict access to University of Pittsburgh for a period of 2 years. |
| Number of Pages: |
131 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Chemical and Petroleum Engineering |
| Degree: |
MS - Master of Science |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
MOBILITY CONTROL, CONFORMANCE CONTROL, CO2-SOLUBLE POLYMER, CO2-SOLUBLE THICKENER, POLYMER, THICKENER |
| Date Deposited: |
01 Feb 2017 18:22 |
| Last Modified: |
01 Feb 2019 06:15 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/30327 |
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