Why are horizontal drilling and hydraulic fracturing used to extract shale gas?

In petroleum engineering, horizontal drilling and hydraulic fracturing are essential for extracting shale gas because the source rock is dense and microporous, causing the gas to diffuse at an extremely slow rate that makes conventional vertical extraction unprofitable.12

Horizontal Drilling

Horizontal drilling allows engineers to access extensive shale seams by turning the borehole to run parallel within the formation. By drilling laterally for hundreds or thousands of meters, operators maximize the well's contact with the gas-bearing rock, significantly increasing the potential volume of gas that can be recovered from a single surface site.3

Hydraulic Fracturing

Because shale is relatively impermeable, hydraulic fracturing (or fracking) is required to release the trapped gas. After the well is cased and perforated, a mixture of water, sand (as a proppant), and chemical additives is injected at extremely high pressure. This process creates and enlarges fissures in the dense rock, allowing the gas to flow into the wellbore. The proppant holds these fractures open, ensuring the gas can continue to migrate toward the production tubing.124