Polymer Flooding of a Heavy Oil Reservoir with an Active Aquifer
- Zhitao Li (University of Texas at Austin) | Mojdeh Delshad (University of Texas At Austin) | Mohammad Lotfollahi (University of Texas At Austin) | Heesong Koh (University of Texas At Austin) | Haishan Luo (University of Texas At Austin) | Harry L. Chang (Chemor Tech Intl LLC) | Jieyuan Zhang (Chemor Tech Intl LLC) | Peter Dempsey (Xcite Energy Resources Ltd) | Charles Lucas-Clements (Xcite Energy Resources LTD) | Barny Brennan (Xcite Energy Resources Ltd)
- Document ID
- Society of Petroleum Engineers
- SPE Improved Oil Recovery Symposium, 12-16 April, Tulsa, Oklahoma, USA
- Publication Date
- Document Type
- Conference Paper
- 2014. Society of Petroleum Engineers
- 5.4.7 Chemical Flooding Methods (e.g., Polymer, Solvent, Nitrogen, Immiscible CO2, Surfactant, Vapex), 5.4.1 Waterflooding, 5.5 Reservoir Simulation, 2 Well Completion, 6.5.2 Water use, produced water discharge and disposal, 4.3.1 Hydrates, 5.4.4 Reduction of Residual Oil Saturation, 5.2.1 Phase Behavior and PVT Measurements, 4.3.4 Scale, 5.5.8 History Matching, 5.4.6 Thermal Methods, 1.8 Formation Damage, 1.6 Drilling Operations, 1.6.6 Directional Drilling, 5.3.1 Flow in Porous Media, 5.6.4 Drillstem/Well Testing, 2.4.3 Sand/Solids Control, 5.3.4 Reduction of Residual Oil Saturation, 5.7.2 Recovery Factors
- UTCHEM, Aquifer, Polymer flood, Viscoelastic polymer, Heavy oil
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In recent years, polymer flood of heavy oil has been extensively studied in laboratories and successfully applied in several fields. This paper reports the laboratory corefloods, development of mechanistic models, and simulation studies of polymer flood in a heavy oil reservoir with active aquifer influxes.
Bentley Field, owned by Xcite Energy Resources, is located on the UK Continental Shelf. Flow tests confirmed the existence of a large, active bottom aquifer which causes polymer loss and decreases the economic attractiveness of polymer flood. To analyze the impact of the aquifer on oil recovery efficiency, a reservoir simulation model was set up. Several development scenarios have been simulated for the optimization of development strategy. Another critical challenge is that the oil viscosity (>1000 cp) exceeds the economic and technical limit of oil viscosity (150 cp) for polymer flood according to the commonly accepted EOR screening criteria. To validate the applicability of polymer flood, two laboratory experiments were conducted with two different sandpacks. Waterflood ceased when water cut reached 90% and only less than 25% of oil in place was recovered. However, the remaining oil saturations after both tertiary polymer corefloods were only about 5%. We investigated the recovery mechanisms and developed a mechanistic model to match the laboratory observations.
Simulation results show that for this heavy oil field with an active aquifer, polymer flood economics can be improved by optimizing well locations, number of horizontal wells, polymer concentrations, polymer injection time, etc. In history matching coreflood experiments, two oil saturation reduction mechanisms were considered: (1) viscous polymer solution reduces viscous fingering and channeling effects especially in heavy oil and also reduces remaining oil saturation after waterflood; (2) remaining oil can be mobilized by viscoelastic properties of synthetic polymer solutions. Both mechanisms were considered in the simulation study where favorable match of oil recovery and pressure drop was obtained.
In this work, we proved polymer flood as a viable technology in a heavy oil reservoir despite the highly unfavorable mobility ratio and strong aquifer influxes. Considering the diminishing conventional oil reserves, polymer flood provides a non-thermal approach for producing heavy oil reserves.
|File Size||3 MB||Number of Pages||19|