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How does hydraulic fracturing help extract natural gas from dense shale and tight limestone?
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natural gas
The Troll A natural gas production platform in the North Sea, 80 km (50 miles) northwest of Bergen, Norway. Troll A, the largest movable structure ever built, rests on the seafloor some 300 metres (990 feet) below the surface and rises more than 100 metres (330 feet) above the sea. The platform regulates the recovery of gas from 40 wells located on the seafloor.
Hydraulic fracturing, or fracking, is a technique used to extract natural gas from dense, low-permeability rock formations like shale and tight limestone that were previously considered too difficult or expensive to develop.123
The process typically involves the following steps:
- Horizontal Drilling: Operators use steerable drill bits to turn the borehole from a vertical path into a horizontal one, allowing the well to extend for thousands of feet through the target rock layer to maximize contact with the resource.24
- Perforation: Once the well is cased, a tool fires small explosive charges through the pipe to create openings into the surrounding rock.5
- Injection: A high-pressure fluid—a mixture of water, sand (as a proppant), and chemical additives—is pumped into the well. This pressure is powerful enough to enlarge existing tiny fissures and create new cracks in the dense rock.52
- Extraction: The sand holds these fissures open, allowing the trapped gas to flow into the well and up to the surface.512
While this technology has unlocked vast energy deposits, it remains a subject of intense debate due to concerns regarding water usage, potential contamination of aquifers, and other environmental impacts.52