11 march 2020 в 00:04

Hydraulic fracturing / fracking

Since 2014, hydraulically fractured horizontal wells have accounted for the majority of new oil and natural gas wells developed in the United States

$Hydraulic fracturing / fracking$

Hydraulic fracturing or fracking is an oil and gas well development process that typically involves injecting water, sand, and chemicals under high pressure into a bedrock formation via the well.

Most fracking wells in use today rely on 2 technologies: hydraulic fracturing, which has been in use since the 1940s, and horizontal drilling, a technique that first became widespread in the 1990s.

Since 2014, hydraulically fractured horizontal wells have accounted for the majority of new oil and natural gas wells developed in the United States, surpassing all other drilling techniques. In 2016, nearly 70 % of the country’s 977,000 producing oil and natural gas wells were horizontally drilled and fracked.

How Hydraulic Fracturing Works:

Drilling

First, the well is drilled vertically. Unconventional natural gas reserves are typically found 2 to 3 km below the earth’s surface, hundreds of metres deeper than drinkable groundwater. Once the vertical well reaches the target formation, the well is turned to drill horizontally through the formation. Horizontal drilling can extend through the resource-bearing formation for a kilometre or more.

Surface Casing

Near-surface layers including soil and groundwater are protected by steel casing and cement that create a solid barrier between the well and underground water sources. Intermediate casing extends even deeper below any fresh water sources and provides an additional protective layer.

Perforating the Wellbore

Prior to fracturing, the wellbore casing is perforated so fracturing fluid can be forced out of the wellbore and into the rock formation, and so oil or natural gas can flow into the wellbore and be brought to the surface. Perforating causes initial cracks in the formation that are extended during the fracturing process.

Fracturing

Fluid comprised of water, sand and a small volume of additives is pumped down the well under high pressure that further fractures the rock after perforation. These fractures extend between 50 and 100 metres from the horizontal wellbore. The sand holds the fractures open to provide pathways for natural gas to flow into the wellbore for extraction. A well is typically fractured once and may produce for up to 20 to 30 years.

Hydraulic fracturing requires an extensive amount of equipment, such as:

high-pressure, high-volume fracking pumps;
blenders for fracking fluids;
storage tanks for water, sand, chemicals, and wastewater.

This infrastructure, plus more, typically arrives at drill sites via heavy trucks.

Fracking is a hotly debated environmental and political issue.
Advocates insist it is a safe and economical source of clean energy; critics, however, claim fracking can destroy drinking water supplies, pollute the air, contribute to the greenhouse gases that cause global warming, and trigger earthquakes.