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Collaborating Authors
Middle East
Abstract This article describes the main features of an unconventional approach to model a polymer flood in the Kalamkas oilfield. This non-standard simulation method is based on specially performed inter-well tracer tests, step-rate tests, pressure fall-off tests, dedicated field studies, well monitoring, and lab analysis. Our approach excludes permeability reduction as a mechanism to provide more mobility reduction than expected from rheology measurements (resistance factor) and by improving the recovery during post-polymer water flooding (residual resistance factor). Evidence is presented to support this exclusion for real field applications. Additionally, our approach places a significant emphasis on history matching bottomhole pressures. Our effort accounts well for the decreased mobility of the injected polymer solution and increased rock permeability during a polymer flood. In contrast to most other simulation approaches to polymer flooding, our method incorporates open fractures during polymer injection and their impact on injectivity and sweep efficiency. A literature review (lab tests and field cases) and our laboratory and field studies confirm the validity of our approach and its advantages over other modern simulator modeling of polymer flooding. From viscosity measurements of back-produced polymer solutions from injectors and well tests (inter-well tracer tests, pressure fall-off tests, step rate tests), we proved that polymer flooding induces fractures or fracture-like features and consequently, the polymer solution flows through the fracture with increased injectivity proportional to a resistance factor. Also, incorporated are expectations during a brine post-flush and the absence of the residual resistance factor (i.e., equal to 1). Implementation of these concepts brings our model closer to reality for simulating polymer floods.
- South America > Suriname > North Atlantic Ocean > Guyana-Suriname Basin > Tambaredjo Field (0.99)
- South America > Guyana > North Atlantic Ocean > Guyana-Suriname Basin > Tambaredjo Field (0.99)
- Asia > Kazakhstan > Mangystau Oblast > Caspian Sea > Precaspian Basin > Kalamkas-More Field > Kalamkas Field (0.99)
- (2 more...)
Modeling and Upscaling Unstable Water and Polymer Floods: Dynamic Characterization of the Effective Finger Zone
Luo, Haishan (The University of Texas at Austin) | Mohanty, Kishore K. (The University of Texas at Austin) | Delshad, Mojdeh (The University of Texas at Austin) | Pope, Gary A. (The University of Texas at Austin)
Abstract Upscaling of unstable immiscible flow remains an unsolved challenge for the oil industry. The absence of a reliable upscaling approach greatly hinders the effective reservoir simulation and optimization of heavy oil recoveries using waterflood, polymer flood and other chemical floods, which are inherently unstable processes. The difficulty in upscaling unstable flow lies in estimating the propagation of fingers smaller than the gridblock size. Using classical relative permeabilities obtained from stable flow analysis can lead to incorrect oil recovery and pressure drop in reservoir simulations. In a recent study based on abundant experimental data, it is found that the heavy-oil recovery by waterfloods and polymer floods has a power-law correlation with a dimensionless number (named viscous finger number in this paper), which is a combination of viscosity ratio, capillary number, permeability, and the cross-section area of the core. Based upon this important finding as well as the features of unstable immiscible floods, an effective-finger model is developed in this paper. A porous medium domain is dynamically identified as three effective zones, which are two-phase flow zone, oil single-phase flow zone, and bypassed oil (isolated oil island) zone, respectively. Flow functions are derived according to effective flows in these zones. This new model is capable of history-matching a set of heavy-oil waterflood corefloods under different viscosity ratios and injection rates. Model parameters obtained from the history match also have a power-law correlation with the viscous finger number. The build-up of this correlation contains reasonable physical meanings to quantitatively characterize the upscaled behavior of viscous fingering effects. Having such a correlation enables the estimation of model parameters in any gridblock of the reservoir by knowing the local viscous finger number in reservoir simulations. The model is applied to several heavy-oil field cases with waterfloods and polymer floods with different heterogeneities. Oil recovery in water flooding of viscous oils is overpredicted by classical simulation methods which do not incorporate viscous fingering properly. Simulation results indicate that the new model reasonably differentiates the oil recoveries at different viscous finger numbers, e.g., lower injection rate leads to higher oil recovery. In contrast, classical simulations obtain close oil recoveries under different injection rates or degrees of polymer shear-thinning, which is apparently incorrect for unstable floods. Moreover, coarse-grid simulations using the new model are able to obtain consistent saturation and pressure maps with fine-grid simulations when the correlation lengths are not smaller than the coarse gridblock size. Furthermore, it is well captured by the model that the shear-shinning polymer solution can strengthen the fingering in high-permeability regions due to increased capillary number and viscosity ratio, which is not observed in waterflood. As a whole, the new model shows encouraging capability to simulate unstable water and polymer floods in heavy oil reservoirs, and hence can facilitate the optimization of heavy-oil EOR projects.
- Asia (1.00)
- North America > United States > Texas (0.94)
- North America > Canada (0.69)
- North America > United States > Louisiana > Pelican Lake Field (0.99)
- Asia > Middle East > Oman > Dhofar Governorate > South Oman Salt Basin > Marmul Field > Al-Qalata Formation (0.99)
- North America > United States > Louisiana > China Field (0.97)
- North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Deep Basin > Mannville Field > Cardium Formation > 2244572 Alberta Mann 16-10-50-10 Well (0.97)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Oil sand, oil shale, bitumen (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Waterflooding (1.00)
- Reservoir Description and Dynamics > Improved and Enhanced Recovery > Chemical flooding methods (1.00)