1. Foam Enhancement of sweep in Fracture System Wei Yan George J. Hirasaki Clarence A. Miller Chemical Engineering Department, Rice University

2. Objective Study the diversion of liquid in heterogeneous fracture network with foam

3. Foam flow in fractures experiment setup Fracture model Syringe pump Air mass flow controller Foam generator Computer for recording pressure difference Surfactant solution Air Transducer Frit HP digital camera

4. Experiment conditions Surfactant: 0.5% C13-4PO+0.5% CS330 Salinity: 0.23% NaCl, 0.07% CaCl 2, 0.04% MgCl 2 Aperture: 0.1mm, 0.2mm, 0.1 mm/0.2 mm (1:2), 0.05 mm/0.15 mm (1:3) Fractional gas flow: 0~0.9 Bubble diameter: 0.4 mm, 0.6 mm

5. Mechanisms affecting apparent viscosity in fracture system

6. Homogeneous parallel plates model 14 inch 12 inch 8 inch6 inch Variable thickness

7. Effect of flow rate and gas fractional flow on apparent viscosity Re=30 Re=0.5

8. Re=30 Water front at different Reynold’s number

9. Effect of bubble size on apparent viscosity

10. Heterogeneous parallel plates model 14 inch 12 inch 8 inch6 inch Variable thickness 10 inch 0.1 mm

11. Foam has higher apparent viscosity at larger thickness Match of apparent viscosity from theory and measurement 0.15 mm thickness 0.05 mm thickness

12. Foam improves sweep of fractured system Less liquid is needed to sweep system with foam LPV – Liquid Pore volume Aperture = 0.05 mm / 0.15 mm, Re = 0.22, D B = 0.4 mm fg=0.0 0.41PV0.82 PV1.23PV1.64 PV2.05 PV6.56 PV fg=0.9 0.04 LPV0.08 LPV0.12 LPV0.16 LPV0.21 LPV0.66 LPV

13. Surfactant solution to sweep entire heterogeneous fracture at different aperture ratio in total pore volume

14. Surfactant solution to sweep entire heterogeneous fracture at different aperture ratio in liquid pore volume 1:3 1:2

15. The model to describe flow in heterogeneous parallel plates P1P1 P2P2 P3P3 P4P4 P 1 =P 2 P 3 =P 4 Impermeable Dykstra-Parsons Model

16. Injection to breakthrough in wide and narrow aperture

17. Calculation of sweep efficiency in fracture network Fracture apertures are with log-normal distribution No crossflow Pressure difference is equal for each layer Gas fractional flow is equal in each layer

18. Calculation of foam/water sweep in heterogeneous fractures with log-normal distribution apertures Set bubble diameter=0.1mm

19. Simulation of foam/water sweep in heterogeneous fractures with log-normal distribution apertures Set bubble diameter=0.1mm

20. Conclusions The foam apparent viscosity in heterogeneous fracture is from two contributions-bubble deformation and liquid slugs between bubbles. The measurement corresponds to the theory. Gas fractional flow and fracture thickness ratio can greatly affect the sweep efficiency. Foam can greatly improve the sweep efficiency in heterogeneous fracture. Dykstra-Parsons model can be applied to simulate the transient state foam flow in heterogeneous fractures

21. Future work Test surfactants’ ability to generate foam in alkaline-surfactant EOR process Study the foam stability with the presence of oil