Experimental study of liquid‐gas flow structure effects on relative permeabilities in a fracture

Abstract

[1] Two-phase flow through fractured media is important in geothermal, nuclear, and petroleum applications. In this research an experimental apparatus was built to capture the unstable nature of the two-phase flow in a smooth-walled fracture and display the flow structures under different flow configurations in real time. The air-water relative permeability was obtained from experiment and showed deviation from the X curve behavior suggested by earlier studies. Through this work the relationship between the phase channel morphology and relative permeability in fractures was determined. A physical tortuous channel approach was proposed to quantify the effects of the flow structure. This approach could replicate the experimental results with a good accuracy. Other relative permeability models (viscous coupling model, X curve model, and Corey curve model) were also compared. Except for the viscous coupling model, these models did not interpret the experimental relative permeabilities as well as the proposed tortuous channel model. Hence we concluded that the two-phase relative permeability in fractures depends not only on liquid type and fracture geometry but also on the structure of the two-phase flow.

The effect of fracture aperture and flow rate ratios on two-phase flow in smooth-walled single fracture

“…Also, similar flow structures were observed on both the smooth-and rough-walled fractures; which differ from the flow structures suggested by Fourar and Bories (1995). Chen and Horne (2004), and Chen (2005) found that the flow structures of gas and water flow in roughwalled fracture is more scattered and tortuous compared to the ones observed with the smooth-walled fracture. Also, they observed phase trapping of gas and water due to fracture aperture variations and to capillary pressure effects.…”

Simulation of Naturally Fractured Reservoirs. State of the Art

“…Chen et al (2004) showed that two-phase flow experiments in a single fracture do not yield linear relative permeability curves. However, such measurements of relative permeability hardly reflect the reservoir flow conditions because of laboratory limitation and of non-representative core samples.…”

“…This model is based on an explicit representation of conductive faults and on the assumption of fluid gravity segregation within the faults, with negligible effects of capillarity. The vertical distribution of fluids within faults then simply obeys the Vertical Equilibrium concept (Coats et al, 1967) reduced to the sole effect of gravity forces. Under these conditions, phases in the fault are vertically segregated according to their densities.…”

Analytical Solutions for Water–gas Flow Through 3d Rock Fracture Networks Subjected to Triaxial Stresses

“…For each D e that ranges from 2.1 to 2.9 ten thousands of random numbers are assigned to R and the corresponding apertures are generated using the parameters tabulated in Table 1. Then, the number of fractures with their apertures in the range [1,3] µm are counted with an interval of 0.2 µm. By fitting these data as shown in Figs.…”

“…[1][2][3][4][5][6] A great number of ways such as theoretical models, experimental methods and simulation approaches have been adopted to characterize the water-gas flow, among which some analytical solutions for the hydraulic properties of unsaturated hydraulic properties of fracture networks have been proposed. [7][8][9][10][11][12] Besides, the fractal dimension that can be used to quantify the geometric properties such as fracture length and aperture distributions of rock fractures has been widely accepted and incorporated into these models.…”