Two-phase fluid numerical simulation on foam fracturing fluid with gas phase being treated as granular

The rheology mechanism of foam fracturing fluid was studied by Eulerian-Eulerian two-phase fluid method with the gas phase being treated as 'granular'. The results show that the decrease in bubble size with rising shear rate was the primary reason of shear thinning behavior of foam fracturing fluid, and the viscosity and non-Newtonian fluid characteristic of foam fracturing fluid were influenced by the bubble phase. Moreover, the increase in viscosity of foam fracturing fluid was mainly caused by the collision and friction between liquid phase and bubbles. The viscosity yielded by friction was dominant at large gas volume. Further, there was almost no slip velocity between liquid phase and bubbles. The turbulent kinetic energy of each phase augmented with increasing volume fraction had the largest value at the wall adjacent region. In addition, the simulation result of effective viscosity agrees with the experiments data. The error between them may be caused by the breaking up and distortion of bubbles in practical fracturing fluid. However, this two-phase fluid model is not suitable for foam fracturing fluid with gas volume fraction higher than 65%.