Surfactants Cumulative

The effects of rate-limited solubilization, subsurface layering and flushing solution density on PCE recovery were evaluated in two separate box studies (Box A and Box B). Box A was flushed with 4% Tween 80 alone to serve as the control case, while Box B was flushed with 4% Tween 80 + 5% EtOH to evaluate the effects of cosolvent addition on PCE solubilization, cumulative PCE recovery, and surfactant delivery. Each box was packed with 20-30 mesh Ottawa sand as the background porous medium, with one rectangular layer of F-70 Ottawa sand above two side-by-side rectangular... 

Cumulative (Longer Term) Effects of Repeated Exposure to Surfactants... 412... 

Long-term surfactant damage to the SC lipid extends from the short-term effects resulting in cumulative loss of barrier function and lipid fluidity leading to profound dryness. The results of an assessment... 

The general observation from DLS studies is that the apparent hydrodynamic diameter increases as the pressure is decreased towards a phase boundary (where surfactant and water will precipitate to form a second phase). Figures 2 and 3 show DLS results for AOT/water micelles in supercritical xenon (at 25 C) and ethane (at 37 C), respectively. Results are presented for [H20]/[A0T] molar ratios (W) of 1 (a) and 5 (b). All measurements were obtained In single-phase systems at constant W. The apparent hydrodynamic micelle diameter decreases with increasing pressure or density of the continuous phase in both fluids. The second cumulant in Equation 1, which is a qualitative measure of the polydispersity of the system, is very close to zero for all conditions of this study. There is no statistically... 

At the end of polymer drive—cumulative 0.33 PV injection (4807 m ), including surfactant injection—the producers started to respond. The water cut decreased from 99% before the test to 87%, and the oil rate increased from 0.2 to 1.9 t/d at the peak rate. However, the response lasted only 90 days. In this pilot, the viscosities of micellar solution and polymer solution were 15.7 mPa-s and 14 mPa s, respectively, about twice the oil viscosity. A good mobility ratio might be the main reason for the positive response. 

Once on the fabric, the quaternaries withstand several rinses in plain water [1,97,98], They are partly removed by anionic surfactants in subsequent washes [6,31], but quat removal is never complete, even after two washes with a detergent [26,96], The situation is probably different with esterquats because of the hydrolysis that takes place under the alkaline conditions of the wash. In fact, only 25% of the DHTDMAC present on the fibers is removed during a wash with SLS, 75% remaining as a catanionic complex [72], Molecules with the longest alkyl chain derivatives best resist cumulative rinses [20],... 

Alkali Surfiictant NM. [Exxon/Tomah] Caustic surfactant hydrotrope used in alkaline Cumulations feu hard surface cleaning solubilizer. 

Figure 1 is the cumulative oil recovery profile of the systems studied. It shows that with the addition of 0.06% IBA into the TRS 10-410/n-dodecane system, the oil recovery by direct surfactant solution flooding (i.e., without waterflooding) is improved from 84.37% to 98.32% after 3.5 PV surfactant solution injection. The TRS 10-80/n-octane system showed an increase in oil recovery from 60% to 91% by the addition of isobutanol (Figure 1). It should be noted that the increase in oil recovery occurs only after the major oil bank comes out (i.e., after 1 PV of produced fluid). We propose that the presence of isobutanol promotes the coalescence of oil droplets in porous media leading to a better oil recovery efficiency. A much more drastic difference is seen in the TRS 10-80/n-octane system, where the tertiary oil recovery increased from 0% without IBA to 76.84% with IBA (Table 1) after 2.7 PV surfactant solution injection. Thus, for both secondary and tertiary oil recovery processes (i.e., with or without brine flooding stage) carried out in these laboratory scale experiments, the addition of isobutanol enhances the oil recovery efficiency presumably by promoting the coalescence in porous media.

It is interesting to note that the shape of the cumulative oil recovery curves in the unconsolidated sandpack is similar to that in the consolidated Berea core (Figures 1 and 9), except that oil is produced at a much faster rate for the sandpacks. Therefore, the oil displacement mechanism is presumably the same in these two porous media for the continuous dilute surfactant solution flooding process. Chou and Shah (22) have shown that 1 or 4 ft sandpacks give identical results for oil recovery and the fluid production... 

Fig. 1. Surfactant flooding experiments in Bentheim sandstone cores (30 cm long, T = 62 ). Oil production versus cumulative injection.

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