Category: Enhanced Oil Recovery

When an alkaline solution is mixed with certain crude oils, surfactant molecules are formed. When the formation of surfactant molecules occurs in situ, the interfacial tension between the brine and oil phases could be reduced. The reduction of interfacial tension causes the microscopic displacement efficiency to increase, thereby increasing oil recovery. Alkaline substances that have…

The basic micellar-polymer process uses a surfactant to lower the interfacial tension between the injected fluid and the reservoir oil. A surfactant is a surface-active agent that contains a hydrophobic (“dislikes” water) part to the molecule and a hydrophilic (“likes” water) part. The surfactant migrates to the interface between the oil and water phases and…

The addition of large molecular weight molecules called polymers to an injected water can often increase the effectiveness of a conventional waterflood. Polymers are usually added to the water in concentrations ranging from 250 to 2000 parts per million (ppm). A polymer solution is more viscous than brine without polymer. In a flooding application, the…

Chemical flooding processes involve the addition of one or more chemical compounds to an injected fluid either to reduce the interfacial tension between the reservoir oil and injected fluid or to improve the sweep efficiency of the injected fluid by making it more viscous, thereby improving the mobility ratio. Both mechanisms are designed to increase…

Because of differences in density and viscosity between the injected fluid and the reservoir fluid(s), the miscible process often suffers from poor mobility. Viscous fingering and gravity override frequently occur. The simultaneous injection of a miscible agent and brine may take advantage of the high microscopic displacement efficiency of the miscible process and the high…

Because of differences in density and viscosity between the injected fluid and the reservoir fluid(s), the miscible process often suffers from poor mobility. Viscous fingering and gravity override frequently occur. The simultaneous injection of a miscible agent and brine may take advantage of the high microscopic displacement efficiency of the miscible process and the high…

The use of inert gases, in particular CO2 and N2, as injected fluids in miscible processes, has become extremely popular. The representation of the process with CO2 or N2 on the ternary diagram is exactly the same as the high-pressure vaporizing process, with the exception that either CO2 or N2 becomes a component and methane is lumped with the intermediates.…

Multiple-contact or dynamic miscible processes do not require the oil and displacing fluid to be miscible immediately on contact but rely on chemical exchange between the two phases for miscibility to be achieved. Figure 11.8 illustrates the high-pressure (lean-gas) vaporizing, or the dry gas miscible process. Figure 11.8 Ternary diagram illustrating the multicontact dry gas miscible process. The…

Multiple-contact or dynamic miscible processes do not require the oil and displacing fluid to be miscible immediately on contact but rely on chemical exchange between the two phases for miscibility to be achieved. Figure 11.8 illustrates the high-pressure (lean-gas) vaporizing, or the dry gas miscible process. Figure 11.8 Ternary diagram illustrating the multicontact dry gas miscible process. The…

The phase behavior of hydrocarbon systems can be described through the use of ternary diagrams such as Fig. 11.6. Crude oil phase behavior can typically be represented reasonably well by three fractions of the crude. One fraction is methane (C1). A second fraction is a mixture of ethane through hexane (C2-C6). The third fraction is the…