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.