Foam Generation in Porous Media

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn steady gas-liquid flow in homogeneous porous media with surfactant present, there is often observed a critical injection velocity or pressure gradient ∇p min at which "weak" or "coarse" foam is abruptly converted into "strong foam," with a reduction of one to two orders of magnitude in total mobility: i.e., "foam generation." Earlier research on foam generation is extended here with extensive data for a variety of porous media, permeabilities, gases (N 2 and CO 2 ), surfactants, and temperatures. For bead-and sandpacks, ∇p min scales like (1/k), where k is permeability, over 2½ orders of magnitude in k; for consolidated media, the relation is more complex. For dense-CO 2 foam, ∇p min exists but can be less than 1 psi/ft. If pressure drop, rather than flow rates, is fixed, one observes an unstable regime between stable "strong" and "coarse" foam regimes; in the unstable regime ∇p is nonuniform in space or variable in time. Results are interpreted in terms of the theory of foam mobilization at a critical pressure gradient.

Distinguishing the Effect of Rock Wettability from Residual Oil on Foam Generation and Propagation in Porous Media

“…Previous studies on foam generation have recognized that a minimum pressure gradient (∇ P min ), or equivalently a critical gas velocity, should be exceeded to mobilize the stationary lamellae and generate strong foam in porous media. − Furthermore, the ∇ P min has been shown to increase with the presence of residual oil. To identify the ∇ P min under the test conditions, the injection velocity was ramped up in a stepwise manner from 4 to 8, to 16, and finally to 32 ft/day and then lowered back to 4 ft/day.…”

Effects Evaluation on Multiround Injection of a N2 Foam & Viscosity Reducer to Improve the Recovery of Fault-Block Heavy Oil Reservoir with Edge-Bottom Water: A Two-Dimensional Visualization Experimental Study

“…This leads to a rapid increase in water cut, and water flooding methods are hard to further improve the recovery factor. , In order to address the low recovery factor in fault-block reservoirs with bottom water, many scholars have conducted research on how to enhance the oil recovery after water flooding. − Various auxiliary water flooding techniques have been implemented in domestic oil fields, such as nitrogen foam flooding and viscosity reducer flooding in the Shengli oilfield, Liaohe oilfield, and Bohai oilfield. − These techniques have all resulted in a decrease in water cut and an increase in crude oil production. Both laboratory studies and field applications have shown that for edge-bottom water fault block reservoirs, nitrogen foam flooding and viscosity reducer flooding technologies have significant advantages among the existing enhanced oil recovery technologies. , …”

Coarsening of Foam in Two Model Fractures with Different Roughness

“…Aqueous foam comprises gas bubbles separated by continuous liquid films. The films are called lamellae and are stabilized by surfactant [1]. Foam has many applications in underground resources, such as aquifer remediation [2], acid stimulation [3], and enhanced oil recovery [4,5].…”

“…1 and Model 2, with dimension 1 × 0.15 × 0.04 m (length × width × thickness). Each model is made of two 2-cm-thick glass plates (Hijman Glas B.V., the Netherlands).…”