ABSTRACT
Petroleum and the equivalent term ‘‘crude oil’’ is a mixture of gaseous, liquid, and solid molecules that occur in rock deposits found in different parts of the world. Oil recovery from porous sedimentary rocks depends on the efficiency with which oil is displaced by some other fluids (Morrow, 1991). The literature reported on enhanced oil recovery (EOR) with microemulsions (Miller and Qutubuddin, 1987). The flow behavior of crude oil, gas, and brine in the porous rock medium of petroleum reservoirs is controlled largely by the interactions occurring at the interfaces within the various fluids. Natural gas is found in many petroleum reservoirs and, in some cases, is the only occupant. The main component of natural gas is methane but other hydrocarbons, such as ethane, propane, and butane, are also present. The sulfur, oxygen, and nitrogen contents of crude oils vary. Early literature reported that the oxygen and nitrogen contents of crude oils are small but the sulfur content can be as high as 2-3 wt% (Roberts, 1977). Crude oils contain different hydrocarbon and heteroatom containing molecules and the comprehensive review of the composition and the chemistry of crude oils was published (Speight, 2006). The content and the chemistry of typical heteroatom containing molecules found in crude oils are shown in Table 1.1.
