(i) Drilling of the oil through the various layers under the earth's surface. (ii) Processing of crude oil to remove heavy oil (iii) Purification of crude oil containing salt water (iv) Heating of the crude oil containing pure mixture of hydrocarbons over a specific range of temperature (v) Separation of constituents by fractional distillation

Crude oil processing is a series of procedures designed to transform raw crude oil extracted from the earth into usable products such as fuel, chemicals, and plastics. Following drilling—which reaches subsurface reservoirs to bring oil to the surface—this complex process begins with separating undesirable elements and heavy hydrocarbons to yield lighter oil fractions suitable for refining.

During desalting, water is introduced to the mixture, encouraging heavy oils and salts to separate and settle. This operation helps prevent equipment corrosion and prepares the oil for refinement, ensuring the efficiency and longevity of subsequent processing steps.

The desalting of crude oil is a critical purification practice aimed at eliminating salt content. This is not only necessary for protecting processing equipment but also for paving the way toward a successful refinement. The desalting process typically involves electrostatic coalescers, which apply electrical charges to promote the coalescence of saltwater droplets, resulting in easier separation from the oil.

Chemical treatments can also be used to enhance separation, by demulsifying the crude oil and breaking emulsions. This leads to a 'washed' crude oil which is substantially free of salts and ready for thermal processing.

The purification of oil is more than desalting; it encompasses the removal of all unwanted materials like water, sediments, and metals that can hamper the refining process. Techniques involve filtration, centrifugation, and magnetic separation to get rid of solid particles and sediments.

Refining these impurities increases the quality and value of the end products. It also minimizes issues during the fractional distillation stage by preventing the buildup of residues that can disrupt operations and reduce the efficiency of separating hydrocarbon fractions.

The separation of hydrocarbons in crude oil is a pivotal part of its processing, which results in the creation of various fuel types and products. Fractional distillation, the most common method employed, relies on the differing boiling points of hydrocarbons to facilitate this separation. In a distillation column, heat induces the vaporization of these hydrocarbons, which then rise and condense at various heights within the column according to their specific boiling points.

This technique efficiently produces streams of products like gasoline, diesel, jet fuel, and lubricants. The accuracy of this separation directly affects the quality and purity of the resulting fuels, underscoring the meticulous control and precision required throughout the distillation process.