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How does hydraulic fracturing help extract oil from tight rock formations?
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petroleum production
A semisubmersible oil production platform operating in water 1,800 metres (6,000 feet) deep in the Campos basin, off the coast of Rio de Janeiro state, Brazil.
Hydraulic fracturing, commonly known as fracking, is a technique used to extract oil from "tight rock" formationsāsuch as shale or dolomiteāthat are characterized by low permeability and low porosity. Because these formations do not allow oil to flow easily, traditional extraction methods are often ineffective.12
The process works as follows:
- Perforation: After a well is drilled and cased, a tool is used to fire explosive charges through the pipe, creating openings that connect the well to the surrounding rock formation.32
- Injection: A high-pressure mixture of water, sand (the proppant), and chemical additives is pumped into the borehole.32
- Fracturing: The intense pressure forces the rock to crack, creating a network of interconnected fissures.32
- Propping: The sand remains in these fissures after the pressure is released, holding them open to provide a permeable path for the trapped oil to flow into the well and up to the surface.32
This method, often combined with horizontal drilling, has been essential in unlocking unconventional tight oil reserves.145