Abstract
To describe accurately the flow characteristic of fracture scale displacements of immiscible fluids, an incompressible two-phase (crude oil and water) flow model incorporating interfacial forces and nonzero contact angles is developed. The roughness of the two-dimensional synthetic rough-walled fractures is controlled with different fractal dimension parameters. Described by the Navier–Stokes equations, the moving interface between crude oil and water is tracked using level set method. The method accounts for differences in densities and viscosities of crude oil and water and includes the effect of interfacial force. The wettability of the rough fracture wall is taken into account by defining the contact angle and slip length. The curve of the invasion pressure-water volume fraction is generated by modeling two-phase flow during a sudden drainage. The volume fraction of water restricted in the rough-walled fracture is calculated by integrating the water volume and dividing by the total cavity volume of the fracture while the two-phase flow is quasistatic. The effect of invasion pressure of crude oil, roughness of fracture wall, and wettability of the wall on two-phase flow in rough-walled fracture is evaluated.
Highlights
Two-phase flow through fractured rock is encountered in many industrial activities such as oil and gas recovery, carbon dioxide storage, and underground oil storage
The solver for the two-phase flow interface was automatically selected for this purpose in COMSOL, and the linear system solver with direct methods was chosen in this paper
The level set method was used to simulate the process of crude oil invasion into an unfilled twodimensional rough-walled fracture saturated by water and to investigate the influences of the fracture roughness and wettability of the fracture wall on the relationship between the invasion pressure of crude oil and the volume fraction of water
Summary
Two-phase flow through fractured rock is encountered in many industrial activities such as oil and gas recovery, carbon dioxide storage, and underground oil storage. The foregoing methods including the ideal conceptual model, cubic law model, and continuum model have been used in simulating two-phase flow in a single fracture with reasonable success, but there were some shortcomings: (1) the ideal conceptual model based on the parallel plate theory cannot describe the rough surfaces of real rock fractures; (2) the classical LCL cannot calculate the fluid inertia and in general overestimates flow through real fractures without considering the wettability of the fracture wall; (3) the continuum model is unable to capture the characteristic of two-phase flow in an unfilled single fracture; (4) the lattice Boltzmann method is limited to model two-phase flow in a large-scale single fracture because this method needs very long calculation time; (5) the effect of the roughness on two-phase flow in an unfilled single fracture is not clearly evaluated.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
