Multiphase flow through fractures has great significance in subsurface
energy recovery and gas storage applications. Different fracture and
flow properties affect flow through a fracture which is difficult to
control in laboratory experiments. Here, we perform lattice Boltzmann
simulations in an ensemble of synthetically generated fractures.
Drainage simulations are performed at different capillary numbers,
wettability, and viscosity ratios. We track the invading front and
quantify breakthrough saturations and show that roughness and
wettability have a profound effect on fluid invasion through a complex
fracture. Invading a more viscous fluid results in more stable
displacement regardless of the capillary number while at very low
capillary numbers, fluid migration is dependent on the inherent
structure of the fracture. Through a systematic investigation, we
develop fluid displacement phase diagrams across multiple fractures, and
demonstrate the importance of natural fracture features of roughness and
wettability in establishing stable versus unstable displacement during
multiphase flow.