Kerogen And Coal

Kerogen and coal are both derived from organic matter. Organic matter is a matter that is derived from the breakdown of plant and animal, it is able to decay or product of decay, it must be composed of organic or carbon compounds. Kerogen and coal and other rocks are formed by diagenetic alteration that takes place during the process called diagenesis. During diagenesis, the sediments will undergo compaction and consolidation that will caused the reduction of volume of voids that are filled by fluids, and the temperature will increase. Such factors are enough for the sediments to alter or change physically and chemically. Kerogen is a highly complex waxy mixture of hydrocarbon compounds (primary organic component of oil shale) where hydrocarbons
are produced as the material is subjected to increase in burial and heating (McSween, Richardson, & Uhle, 2003), it is thought to form during the early stages of diagenesis from mixtures of partially altered, refractory biomolecules (Tregelaar et al. 1989). Kerogen is modified by temperature ultimately to produce petroleum hydrocarbons, it is also insoluble in water and in organic solvents such as benzene or alcohol.
Upon heating under pressure, the large paraffin molecules break down into recoverable gaseous and liquid substances resembling petroleum. This property makes oil shale a potentially important source of synthetic crude oil. The potential yield of petroleum products depends on the type of kerogen. There are four types of kerogen, type I is known as lignite, which are derived from algal or bacterial remains, are relatively rare but have the highest oil potential among the four types. These materials formed in fine-grained organic rich muds deposited under anoxic conditions in quiet shallow water environments, such as lagoons and lakes. Type II are known as exinite which are the most common and are usually formed in marine environments, exinites are mixtures of phytoplankton, zooplankton, and microbial organic matter under reducing conditions, but they also be formed from higher plant debris. Exinite yield hydrocarbons lower than lignite but it still produced oil shales of commercial value and sourced a large number of oil and gas fields (Kilops and Kilops 1993). The third type is known is vitrinite, it is
derived from vascular plants and may contain identifiable woody plant debris, it is usually not extensively altered by microbial degradation, which may be a result of the materials rapid sedimentation and burial. Vitrinite generally occurs as coals or coaly shales; thus, it is similar to coal in composition and behavior with increasing burial. The fourth type is inertinite, which is composed primarily of black opaque debris potentially formed from the deposition of highly oxidized, higher plant material. It doesn’t generate hydrocarbon potential and is sometimes not considered a true kerogen (McSween, Richardson, & Uhle, 2003).