Extending Foam Technology from Improved Oil Recovery to Environmental Remediation

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn the petroleum industry, foams are used for improved oil recovery, reducing gas breakthrough to productions wells, and diverting acid in well-stimulation treatments. A substantial body of research on foam for these applications is extended here to the high-permeabilities and low pressures of environmental remediation, through both laboratory experiments and computer simulations based on the laboratory results.New data confirm that the two steady-state flow regimes identified by Alvarez et al. for petroleum applications exist under conditions relevant to groundwater remediation. The low-quality regime is strongly shear-thinning, in agreement with Alvarez et al. The high-quality regime is more sensitive to surfactant concentration than the low-quality regime, while the low-quality regime is more sensitive to permeability. Therefore, diversion between layers differing in permeability would be more effective in the high-permeability regime, while the low-quality regime has advantages for injectivity and liquid diversion.A foam simulator can be fitted to these steady-state foam data. Simulations indicate that foam can propagate without gravity segregation over long distances at an overall average pressure gradient of well under 1 psi/ft. Moreover, a simple correlation for gravity segregation developed for petroleum applications works well for aquifers overlain by a vadose zone, as long as the assumptions of that correlation (Newtonian rheology, incompressible flow) are satisfied.Local steady state would not be achieved in the field if pressure gradient were insufficient for foam generation, however. New results indicate that at moderate ∇p foam may exist in an unstable regime between strong and coarse foam.

Dynamic Simulations With an Improved Model for Foam Generation

“…If strong foam is created, it exists in two steady-state flow regimes (Mamun et al 2002;de Vries and Wit 1990;Alvarez et al 2001;Kam and Rossen 2003;Rossen and Wang 1999;Kim et al 2004). One is described pre-viously: If P c is close to P c * (S w close to S w *), then pressure gradient |ٌp| is nearly independent of gas superficial velocity.…”

“…Foam can improve sweep efficiency in gas-injection improved oil recovery (IOR) processes (Schramm 1994;Rossen 1996;Terdre 2003), redirect acid flow in matrix acid stimulation (Gdanski 1993;Cheng et al 2002;Nguyen et al 2003), and increase the efficiency of environmental remediation of aquifers (Hirasaki et al 2000;Mamun et al 2002). A continuing goal of foam research is the development of a fully mechanistic, predictive model.…”

Mechanistic simulation of continuous gas injection period during surfactant-alternating-gas (SAG) processes using foam catastrophe theory

“…The concept gained in EOR is also implemented in the recovery of non-aqueous phase liquids (NAPLs) such as petroleum oils, trichloroethylene (TCE) and perchloroethylene (PCE) in shallow subsurface remediation treatments. The foreign materials injected into the contaminated formation help displace or dissolve pollutants to clean up groundwater (Mamun et al, 2002;Rong, 2002). The use of such an in situ remediation technology is believed to be superior to the ex situ remediation technology in terms of remediation time and process costs.…”

Foam Flooding with Ultra-Low Interfacial Tension to Enhance Heavy Oil Recovery

“…However, the ability of foam increasing the resistance to the flow of steam or gas in a porous medium is affected by the ratio of gas to liquid (sometimes called"quality"). [14,15] If the ratio is too small, the surfactant agent can't foam enough, and the ability of resistance is poor. But on the other hand, if the ratio is too large, it is not economic, and also the foam generated maybe unstable.…”