Simulating Foam Processes at High and Low Foam Qualities

Abstract

fax 01-972-952-9435. AbstractFoams used for gas or acid diversion exhibit two flow regimes, depending on foam quality. Two foam simulators, one the most widely used commercial foam simulator and the other developed at our university, fit steady-state foam behavior in both regimes. A simple procedure is described for fitting simulator parameters to a set of steady-state coreflood data and examples are shown. Fitting model parameters to a single coreflood data can err by fitting this datum to the wrong flow regime.Shear-thinning reported in the "low-quality regime" can increase foam injectivity in radial flow. Foams in lowquality regime fit the same correlation for overcoming gravity override previously derived for foam in the highquality regime. The flow regime does greatly affect the effect of capillary crossflow on foam diversion between layers differing in permeability, however.Capillary crossflow harms diversion between adjacent layers, as found earlier, but the magnitude of the effect is much less for foam in the low-quality regime, and no single correlation matches all the results. Capillary crossflow can actually increase (by a small amount) diversion from adjacent layers differing somewhat in permeability to distant layers with muchdifferent permeability.

Understanding aqueous foam with novel CO2-soluble surfactants for controlling CO2 vertical sweep in sandstone reservoirs

“…In our current work, the surfactant concentration and dry-out effects are considered and some typical values are chosen, as shown in Table 1. Here, we chose 100 for fmmob, which is less than these employed by earlier researchers, such as 1000 (Rossen et al 2006), 3000 (Rossen and Shen 2007;Jamshidnezhad et al 2008a), or 5000 (Cheng et al 2000;Rossen and Renkema 2007;Kloet et al 2009), because we believe too strong foam used previously masked some details in the foam process, which is crucial for the novel foam. Meanwhile, it is also much less than the result of coreflood matching (Ma et al 2013) because the foam in 3D is much weaker than in 1D, which has been demonstrated by Li et al (2006).…”

Effect of Permeability on Foam-model Parameters and the Limiting Capillary Pressure

“…Parameter fmcap should be set to the smallest capillary number expected to be encountered by foam in the simulation (Cheng et al, 2000;Boeije and Rossen;, and epcap represents the extent of shear-thinning behavior. Newtonian behavior corresponds to epcap = 0 and positive epcap to shearthinning behavior.…”

“…We have modified the procedure explained by Ma et al (2013Ma et al ( , 2014 by adding shear-thinning function because in their approach smaller values can be assigned to epdry, although as shown later choosing very large values of epdry (as described by Cheng et al, 2000;Boeije and Rossen, 2013), does not alter the general conclusions of this paper. The procedure used here, described in Appendix B, seeks a least-squares fit to all the app f  data subject to weighting and constraints supplied by the user.…”

“…The second group of models represents the effect of bubble size implicitly, through a mobility-reduction factor that depends on saturations, superficial velocities and other factors (e.g. Patzek et al;1989;Mohammadi et al, 1993;Cheng et al;2000). We call this second group "implicit-texture" (IT) models.…”

“…PB models can be restructured to assume local equilibrium (LE) between the dynamics of lamella creation and destruction; all current IT models assume LE. These models contain adjustable parameters that are estimated by fitting the model to experiments (Cheng et al, 2000;Boeije and Rossen, 2013;Rossen and Boeije, 2013;Ma et al, 2013Ma et al, , 2014Lotfollahi et al, 2015). Several different foam models can fit the steady-state mobility of strong foam in a given porous medium to a satisfactory degree (Lotfollahi et al, 2015).…”