Development of a Fully Coupled Two-phase Flow Based Capacitance Resistance Model (CRM)
- Fei Cao (University of Texas at Austin) | Haishan Luo (University of Texas At Austin) | Larry W. Lake (University of Texas At Austin)
- 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
- 5.4.1 Waterflooding, 2.2.2 Perforating, 4.1.2 Separation and Treating, 5.2 Reservoir Fluid Dynamics, 5.2.1 Phase Behavior and PVT Measurements, 4.3.4 Scale, 5.5.8 History Matching, 5.4.2 Gas Injection Methods, 4.1.5 Processing Equipment, 5.8.7 Carbonate Reservoir
- Capacitance Resistance Model, well connectivity, reservoir management, injection scheme optimization, fractional flow
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The capacitance resistance model (CRM) is a popular reservoir model for describing injector-producer connectivity using nonlinear regression techniques. The CRM model is widely used as a complement to real time reservoir analysis and improved oil recovery in water and CO2 floods. However, the current CRM model is based on a material balance of the total fluid and only the pressure propagation equation is considered. However, saturation changes are also important especially when the water cut is small. To overcome this limitation, this paper proposes a coupled CRM model based on two-phase flow by incorporating fractional flow theories.
In the coupled CRM model, we construct material balances on both total fluid and oil. Relative permeability is introduced to separate the effect of oil flow from the flow of total fluid. The Koval method is incorporated to estimate the dynamic pore volume. An IMPES scheme is used to update pressure and saturation equations at each time step. By semi-analytically coupling the pressure and saturation in a producer-based control volume and using constrained multivariate nonlinear regression, the new coupled model can quantify the inter-well connection and the average saturation. As a result, the coupled CRM model can be extended to the whole time frame of water and gas floods.
This new model was tested in heterogeneous synthetic fields and then applied to field cases. Both studies show that the connectivities and time constants obtained are reasonable and correspond well with field geology knowledge. The saturation profile also matches the simulation results. The coupled CRM model is also compared with current CRM model. The results indicate that the connectivities can be different. Further validation and prediction verified that the coupled model is more accurate to describe well connections.
By incorporating the saturation variations to reflect two-phase flow, the coupled CRM model successfully overcomes the limitation of previous version by extending it from being used only in mature floods to the whole life of water and gas floods. This work can lead to a more informed workflow of optimizing injection scheme, and ultimately serve the goal of improving oil recovery.
|File Size||3 MB||Number of Pages||16|