Abstract
Foam is a promising means to reduce gas influx into oil wells, control gas flow in improved oil recovery processes, direct acid flow in matrix acid well treatments, and improve the efficiency of environmental-remediation processes. Recent laboratory research in a wide range of porous media shows that creating foam in steady flow in homogeneous media requires exceeding a minimum pressure gradient. Data fit trends predicted by a theory in which foam generation depends on attaining sufficient ∇p to mobilize liquid lenses present before foam generation. Data show three regimes: a coarse-foam regime at low ∇p, strong foam at high ∇p, and, in between, an transient regime alternating between weaker and stronger foam.
Here for the first time a population-balance foam model incorporates bubble-creation function that depends on pressure gradient. The new model reproduces the three foam regimes seen in the laboratory, the abrupt occurrence of foam generation at a threshold velocity or pressure gradient, hysteresis in experimental results, the interplay between foam stability and foam generation, the effect of injected liquid fractional flow on foam generation, and foam behavior in the high-quality and low-quality steady-state strong-foam regimes. The details of the lamella-creation function have little effect on rheology of strong foam, which is controlled by other mechanisms. The predicted fractional-flow curves are complex. This model is a necessary step toward quantitative prediction of foam performance in the field.
