Evaluation of the impact of polymer thermal degradation on polymer flooding performance in giant heterogeneous carbonate reservoirs
File(s)
Author(s)
Alsaleh, Abdulaziz Abdullah M
Type
Thesis
Abstract
This thesis quantifies how polymer thermal degradation and gravity jointly control polymer flooding performance in giant, high-temperature carbonate reservoirs with large injector–producer spacing. An integrated framework was developed combining Buckley–Leverett analysis extended for polymer and gravity effects, validated 1D/2D numerical models, and 3D field-representative sector simulations based on a scaled COSTA carbonate model. A staged Resolution-IV Design of Experiment isolated controlling factors, while a semi-analytical slug-sizing guide supported by statistical screening defined the most probable slug-size window in oil-wet and mixed-wet systems.
Polymer performance was governed primarily by thermal stability. ATBSA sustained viscosity and recovery at 100 °C across injector–producer spacings of 1–5 km, whereas HPAM performance declined rapidly due to degradation. Slug size was a critical parameter: validation of the semi-analytical model confirmed an optimum of approximately 0.34–0.40 PVI, with statistical analysis indicating a most-probable range of 0.31–0.43 PVI. Larger slugs produced diminishing returns once displacement efficiency approached saturation. Gravity interacted with degradation in a time-dependent manner. At early time (≤ 1 PVI), recovery was dominated by polymer stability and slug size. At later time, gravity enhanced recovery in degraded floods (HPAM and waterflooding) but had limited influence when viscosity was preserved by ATBSA due to its favourable mobility ratio.
Field-scale simulations demonstrated ATBSA performance under peripheral line-drive injection schemes typical of Middle Eastern giant carbonates with well spacings of 1–5 km. ATBSA achieved approximately 10% incremental recovery over waterflooding at 3–5 km spacing, closely matching the no-degradation benchmark, while HPAM performance deteriorated under identical conditions. Gains were attributed primarily to early-time improvements in displacement and sweep efficiency, with gravity contributing marginally at late time.
The thesis provides practical deployment guidelines, including polymer screening by half-life versus exposure time, targeting slug sizes near 0.34 PVI, and accounting for degradation–gravity interactions in wide-spacing field applications.
Polymer performance was governed primarily by thermal stability. ATBSA sustained viscosity and recovery at 100 °C across injector–producer spacings of 1–5 km, whereas HPAM performance declined rapidly due to degradation. Slug size was a critical parameter: validation of the semi-analytical model confirmed an optimum of approximately 0.34–0.40 PVI, with statistical analysis indicating a most-probable range of 0.31–0.43 PVI. Larger slugs produced diminishing returns once displacement efficiency approached saturation. Gravity interacted with degradation in a time-dependent manner. At early time (≤ 1 PVI), recovery was dominated by polymer stability and slug size. At later time, gravity enhanced recovery in degraded floods (HPAM and waterflooding) but had limited influence when viscosity was preserved by ATBSA due to its favourable mobility ratio.
Field-scale simulations demonstrated ATBSA performance under peripheral line-drive injection schemes typical of Middle Eastern giant carbonates with well spacings of 1–5 km. ATBSA achieved approximately 10% incremental recovery over waterflooding at 3–5 km spacing, closely matching the no-degradation benchmark, while HPAM performance deteriorated under identical conditions. Gains were attributed primarily to early-time improvements in displacement and sweep efficiency, with gravity contributing marginally at late time.
The thesis provides practical deployment guidelines, including polymer screening by half-life versus exposure time, targeting slug sizes near 0.34 PVI, and accounting for degradation–gravity interactions in wide-spacing field applications.
Version
Open Access
Date Issued
2025-10-01
Date Awarded
2026-03-01
Copyright Statement
Attribution-NonCommercial 4.0 International Licence (CC BY-NC)
License URL
Advisor
Muggeridge, Ann
Blunt, Martin J.
Sponsor
Saudi Aramco
Publisher Department
Department of Earth Science & Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)