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Hydrocarbons Extraction

In News

  • Recently, the geological processes, extraction methods, and environmental impact of hydrocarbon extraction seen in the news.

About ‘Hydrocarbon’

  • The term ‘hydrocarbon’ is self-explanatory which means compounds of carbon and hydrogen only.
  • Over millennia, mighty geological processes in the earth’s crust heated and compressed together pieces of life forms that had been dead for a while. Eventually, this mulch of organic matter accumulated as hydrocarbons inside rock formations.
  • Categories: Depending upon the types of carbon-carbon bonds present, they can be classified into three main categories –
  • Saturated Hydrocarbons are important sources of energy and they contain carbon-carbon and carbon-hydrogen single bonds.
  • Unsaturated: They contain carbon-carbon multiple bonds – double bonds, triple bonds, or both
  • Aromatic hydrocarbons: They are a special type of cyclic compounds.
  • Occurrence: The most common forms in which these hydrocarbons exist in subterranean rock formations are natural gas, coal, crude oil, and petroleum.
  • They are usually found in underground reservoirs created when a more resistant rock type overlays a less resistant one, in effect creating a lid that causes hydrocarbons to accumulate below it.
  • Such formations are important because otherwise, the hydrocarbons would float to the surface and dissipate.
  • Experts use the tools, methods, and techniques of the field of petroleum geology to assess these rocks, including checking for their porosity and permeability.
  • If a rock formation is highly porous, it could hold a larger quantity of hydrocarbons.
  • The primary source of hydrocarbons in this rocky underground is called kerogen: lumps of organic matter.
  • Kerogen can be deposited from three possible sources: as the remains of a lake (lacustrine), of a larger marine ecosystem, or of a terrestrial ecosystem.
  • Lacustrine kerogen yields waxy oils; marine kerogen, oil, and gas; and terrestrial kerogen, light oils, gas, and coal.
  • Applications : Hydrocarbons are sources of energy and are also used for the manufacture of polymers like polythene, polypropene, polystyrene, etc.
  • Higher hydrocarbons are used as solvents for paints. They are also used as the starting materials for the manufacture of many dyes and drugs.

Extraction

  • Drilling and reservoir engineers are responsible for extracting as much of the hydrocarbons.
  • The first task is to create a production well, the principal hole through which the reservoir will be drained to the surface; its location is chosen to maximize the amount of drainage.
  • The production profile of a well can be split into three phases:
  • Primary: It banks on natural processes, like pressure differences between the reservoir and the well, and less dense compounds floating to the top
  • Secondary: are concerned with inducing artificial pressure in the rock to maintain the differential (e.g. by injecting water into it or diluting the hydrocarbon mix to help it flow better).
  • Tertiary: focused on forcing the remainder into the well. Steam injection is a common example of such an enhanced recovery method.
  • The process of recording the rock cuttings by depth and studying their properties is called mud-logging.
  • Once the production well has been drilled, it has to be prepared to drain the hydrocarbons – a step called completing.

Handling of depleted well

  • An well abandoned needs to be plugged so that its contents – both the hydrocarbons and the gases accumulating in the borehole – don’t escape into their surroundings.
  • The most exhaustive way to conclude operations at a well, whether on land or offshore, is to decommission it, but this process is expensive and often commercially infeasible for the proponent.
  • Improperly abandoned wells are a major source of methane emissions – to go with the emissions released during the production and use of various components required to extract hydrocarbons.