Foams for Mobility Control and Improved Sweep Efficiency in Gas Flooding

Abstract

TX 75063-3636, U. S.A.,fax 01-972-952-9435. AbstractThis experimental investigation studied the use of additives to enhance foam properties and improve the in-situ generation of foams for improving gas flooding sweep efficiency. Some of the parameters affecting foam performance were polymer concentration, different surfactants and their concentration, aqueous phase salinity and pH, and effect of ffow rate (or shear rate).Performance of polymer enhanced foams (PEF) was much better when compared to conventional foams. Polyacrylamide polymers were used as an additive. Higher foam resistance and longer foam persistence were achieved by using relatively low concentrations of polymers. The studies also showed that the foam performance was significantly improved over a broad range of polymer concentrations.A number of other investigators have shown that foams are severely affected in the presence of oil. This is especially true of lighter or less viscous oils, and the destabilizing effect is magnified with a higher salinity aqueous phase. PEF with a low salinity aqueous phase showed improvement in foam stability. The effective viscosities of PEF were higher than those of conventional foams with a high salinity aqueous phase and the presence of lighter oils. Further, PEF reduced the negative impact of oils on foam mobility. Of the surfactants studied, alpha olefin sulfonates were tolerant to high salinity brines as well as being compatible with polymer additives. Other surfactants, including amine oxide surfactants, were also studied and showed unusually high foam resistance and stability. Introduction..__ ---_.. Because of recent advances in technology, C02 flooding has become a readily available improved oil recovery method. Significant amounts of residual oil can be recovered by carbon dioxide (COJ flooding. Studies' have shown increasing trends for C02 flood projects in the United States, as well as in other countries. However, many, if not all, gas flooding field projects are often hampered by early C02 breakthrough, poor sweep efficiency, and inefficient oil recovery due to viscous fingering resulted from a low gas phase visco-sity and an unfavorable mobility ratio.Poor sweep efficiency may also be caused by stratification or fracturing. Reservoir heterogeneity, particularly layering, is one of the most important factors that affects C02 flood performance. C02 mobility is usually high relative to that of other reservoir fluids, and the resulting unfavorable mobility ratio enhances fingering that initially results from reservoir heterogeneity or gravity override. In more heterogeneous reservoirs, the C02 floods some layers more easily because of differences in porosity and permeability. In this case, the C02 breaks through faster to the producing wells. More C02 is then required over the lifetime of the ffood, which leads to higher C02 costs per barrel of oil recovered and greater handling and recycle expenses.A need to control gas phase mobility has resulted in many studies of processes which may alleviate the adve...

Design and Fabrication of Anionic/Cationic Surfactant Foams Stabilized by Lignin–Cellulose Nanofibrils for Enhanced Oil Recovery

“…According to Hiraski, foam is defined as a dispersive system, in which liquid is the continuous phase with gas phase trapped in the thin liquid films called lamellae . A viscosity increase of the displacing phase in the presence of bubbles enables more gas to invade the lower permeability region . Moreover, the foaming agent is capable of decreasing capillary forces and stimulating microscale displacement efficiency through reducing oil–water interfacial tension .…”

Mechanistic Studies of Improved Foam Eor Processes

“…The effects of HPAM polymer addition on foam made of a variety of surfactants have also been studied by Zhu et al(1998). They measured PEF mobility in sandpacks of varying permeability (130, 50, 13 and 3 darcy) and in sandstone cores of 1.0 and 0.2 darcy.…”

Research on Mechanism of Enhancing Recovery of Heavy Oil With N2 Huff-n-Puff Assisted by Viscosity Reducer

“…This is because of the foaming pugging effect of 4# viscosity reducer. The foam plugged the large channel, which increased the resistance of N 2 flow in the channel, but did not affect the N 2 displacement of oil (Zhu et al, 1998;Li et al, 2017). Finally, the oil production of low permeability sandpack was improved.…”