|Publisher||Society of Petroleum Engineers||Language||English|
|Content Type||Conference Paper|
|Title||A New Approach to Model Hysteresis and Its Impact on CO2-EOR Processes with Mobility Control Strategies|
Mohammad R. Beygi, Mojdeh Delshad, Venkateswaran S. Pudugramam, Gary A. Pope, and Mary F. Wheeler, SPE, The University of Texas at Austin
SPE Western Regional & AAPG Pacific Section Meeting, 2013 Joint Technical Conference, Apr 19 - 25, 2013 2013, Monterey, CA, USA
Society of Petroleum Engineers
|6.3.2 Multi-phase Flow
6.3.1 Flow in Porous Media
6.4 Primary and Enhanced Recovery Processes
|Keywords||CO2-EOR, Gas Mobility Control, Hysteresis, Foam, WAG|
Mobility control methods have the potential to improve coupled CO2 enhanced oil recovery and carbon sequestration (CO2-EOR). There is a need for improved three-phase relative permeability models with hysteresis including especially the effects of cycle dependency so that more accurate predictions of these methods can be made. We propose a new three-phase relative permeability model with hysteresis applicable to different fluid configurations in porous medium under different wettability conditions. The model also includes compositional effects. Three-phase parameters are estimated based on saturation-weighted interpolation of two-phase parameters. The proposed hysteresis model is an extension of the Land trapping model but with a dynamic Land coefficient introduced. The trapping model estimates a constantly increasing trapped saturation for intermediate- and non-wetting phases. The model overcomes some of the limitations of existing three-phase hysteresis models for non-water wet rocks and mitigates the complexity associated with commonly applied models in numerical simulators. The model is validated using multi-cyclic three-phase water-alternating-gas experimental data for non-water wet rocks. Numerical simulations of a carbonate reservoir with and without hysteresis were used to assess the impact of the saturation history and saturation path on gas entrapment and oil recovery.
Background and Literature Review
Unlike water-wet rocks, mixed-wet reservoirs show a continuous oil phase in three-phase flow resulting in small, yet non-zero, values of the oil relative permeability (Salathiel, 1973). The dependence of the oil isoperms on one or two phase saturations in saturation space is complex and difficult to predict a priori (Dijke M. v., 2001). Moreover, by studying three-phase displacement processes and pore-scale mechanisms in etched micromodels, it was revealed that fluid configurations can be categorized based on the spreading coefficient
The necessary condition for a spreading oil layer between aqueous and gas phases is non-negative ; otherwise, a three-phase contact line exists. In the non-spreading case, oil is wetting relative to gas and water or gas could be the wetting phase in non-water wet media depending on the gas-water contact angle. The contact angle plays a crucial role in fluid configurations in porous media. The difference between oil-water and gas-oil interfacial tension could result in either the aqueous or gas phase as the intermediate-wetting phase in oil-wet rocks. This complex fluid configuration and flow in porous media delineate regions in saturation space where commonly used models fail to replicate the physical behavior. There are commonly used correlations based on an assumed fluid configuration that are not easy to generalize to other fluid configurations.