Foam Enhancement of sweep in Fracture System Wei Yan George J. Hirasaki Clarence A. Miller Chemical Engineering Department, Rice University Objective • Study the diversion of liquid in heterogeneous fracture network with foam Foam flow in fractures experiment setup Transducer Surfactant solution HP digital camera Syringe pump Frit Fracture model Air Foam generator Air mass flow controller Computer for recording pressure difference Experiment conditions Surfactant: 0.5% C13-4PO+0.5% CS330 Salinity: 0.23% NaCl, 0.07% CaCl2, 0.04% MgCl2 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 Mechanisms affecting apparent viscosity in fracture system Homogeneous parallel plates model Variable thickness 12 inch 14 inch 6 inch 8 inch Effect of flow rate and gas fractional flow on apparent viscosity 100.0 Apparent viscosity (cp) aperture = 0.2 mm,mean bubble size DB= 0.6 mm 10.0 fg=0.67 fg=0.67 from theory fg=0.5 fg=0.5 from theory fg=0.33 fg=0.33 from theory fg=0.2 fg=0.2 from theory fg=0.0 fg=0.0 from theory 1.0 Re=0.5 0.1 0.001 Re=30 0.010 0.100 Flow velocity (m/s) 1.000 Water front at different Reynold’s number Re=0.5 Re=30 Effect of bubble size on apparent viscosity 0.5% C13-4PO+0.5% CS330, 0.23% NaCl, 0.07% CaCl2, 0.04% MgCl2, gas fractional flow = 0.67, aperture = 0.2 mm Apparent viscosity (cp) 100.0 10.0 flow velocity=2.2 cm/s flow velocity=2.2 cm/s from theory 1.0 0.1 0.1 1.0 Mean bubble size (mm) 10.0 Heterogeneous parallel plates model Variable thickness 0.1 mm 12 inch 14 inch 10 inch 6 inch 8 inch Foam has higher apparent viscosity at larger thickness Match of apparent viscosity from theory and measurement aperture = 0.05mm/0.15mm,D B=0.4mm, Re = 0.22 100 Apparent viscosity (cp) 0.05mm aperture from measurement 0.05mm aperture from theory 0.15mm aperture from measurement 0.15mm aperture from theory 0.15 mm thickness 10 0.05 mm thickness 1 0 0.2 0.4 0.6 Gas Fractional Flow 0.8 1 Foam improves sweep of fractured system Less liquid is needed to sweep system with foam Aperture = 0.05 mm / 0.15 mm, Re = 0.22, D B = 0.4 mm fg=0.0 0.41PV 0.82 PV 1.23PV 1.64 PV 0.08 LPV 0.12 LPV 0.16 LPV 2.05 PV 6.56 PV 0.21 LPV 0.66 LPV fg=0.9 0.04 LPV LPV – Liquid Pore volume Surfactant solution to sweep entire heterogeneous fracture at different aperture ratio in total pore volume DB=0.4mm, Re=0.22 10.0 Total Pore Volume 1:3 1.0 1:2 0.1 0.0 0.2 0.4 0.6 Gas Fractional Flow 0.8 1.0 Surfactant solution to sweep entire heterogeneous fracture at different aperture ratio in liquid pore volume DB=0.4mm, Re=0.22 Liquid Pore Volume 10.0 1:3 1.0 1:2 0.1 0.0 0.2 0.4 0.6 Gas Fractional Flow 0.8 1.0 The model to describe flow in heterogeneous parallel plates Dykstra-Parsons Model Impermeable P1 P3 P2 P4 P1=P2 P3=P4 Injection to breakthrough in wide and narrow aperture Total Pore Volume 10.0 DB=0.4mm, Re=0.22 aperture 0.05mm/0.15mm Dykstra-Parsons model 1.0 0.05mm aperture from experiment 0.05mm aperture from theory 0.15mm aperture from experiment 0.15mm aperture from theory 0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 Gas Fractional Flow 0.7 0.8 0.9 1.0 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 Calculation of foam/water sweep in heterogeneous fractures with log-normal distribution apertures Set bubble diameter=0.1mm Simulation of foam/water sweep in heterogeneous fractures with log-normal distribution apertures Set bubble diameter=0.1mm 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 Future work Test surfactants’ ability to generate foam in alkaline-surfactant EOR process Study the foam stability with the presence of oil