Oil Recovery and Surface Forces

Oil recovery from reservoirs is not a 100% process from rock since not all of the oil in a reservoir is recovered. This means that all the oil recovered until now leaves some 20-40% residual oil in the depleted reservoirs. This may be considered as an advantage in the long run because, as the shortage of oil supplies approaches, one may be forced to develop technologies to recover the residual oil. 

In the tertiary process, more complicated chemical additives are designed for a particle reservoir. In all these recovery processes, the interfacial tension (IFT) between the oil phase and the water phase is needed. 

The pressure difference to push the oil drop may be larger than that to push the water, thus leading to the so-called bypass phenomena. In other words, as water flooding is performed, due to bypass, there is less oil produced, while more water is pumped back up with the oil. 

by decreasing the value of interfacial tension (with the help of SAAs from 50 mN/m to 1 mN/m), the pressure needed for oil recovery would be decreased. 

In the water-flooding process, mixed emulsifiers are used. Soluble oils are used in various oil-well-treating processes, such as the treatment of water injection wells to improve water injectivity and to remove water blockage in producing wells. The same method is useful in different cleaning processes with oil wells. This is known to be effective since water-in-oil microemulsions are found in these mixtures, and with high viscosity. The micellar solution is composed essentially of hydrocarbon, aqueous phase, and surfactant sufficient to impart micellar solution characteristics to the emulsion. The hydrocarbon is crude oil or gasoline. Surfactants are alkyl aryl 

---