The primary difference between fracking and conventional drilling lies in the geological formations they target and the methods used to extract oil and natural gas. Conventional drilling accesses hydrocarbons that are relatively easy to reach and flow naturally, while fracking is employed to release oil and gas trapped in dense, impermeable rock formations.
Key Differences
- Target Formation: Conventional drilling typically targets large reservoirs of oil or gas that can be accessed by drilling vertically. These reservoirs are often found in permeable rock formations like sandstone or limestone, where hydrocarbons have migrated and accumulated. In these formations, the oil and gas can flow relatively freely into a wellbore.
- Extraction Method: In contrast, hydraulic fracturing involves injecting high-pressure fluid into shale formations to release tightly held hydrocarbons. Dense rocks like shale have pores containing oil and gas, but the rock's low permeability prevents the hydrocarbons from flowing easily. Fracking creates artificial pathways for these hydrocarbons to escape.
Based on the provided reference: Conventional drilling typically targets large reservoirs of oil or gas that can be accessed by drilling vertically, while hydraulic fracturing involves injecting high-pressure fluid into shale formations to release tightly held hydrocarbons.
How They Work
Understanding the process helps illustrate the distinction:
- Conventional Drilling Process:
- A vertical wellbore is drilled down to the permeable target reservoir.
- Once the reservoir is reached, the natural pressure of the formation often pushes the oil or gas up the wellbore.
- If pressure is insufficient, pumps may be used to lift the hydrocarbons to the surface.
- This method relies on the existing geological conditions allowing hydrocarbons to flow naturally.
- Hydraulic Fracturing (Fracking) Process:
- A well is drilled, often vertically and then horizontally, into a dense, hydrocarbon-rich layer like shale.
- A mixture (primarily water, sand, and a small percentage of chemicals) is pumped down the wellbore at extremely high pressure.
- This high-pressure fluid creates and expands tiny cracks (fractures) in the surrounding rock.
- The sand (known as "proppant") holds these fractures open after the pressure is released.
- The released oil and gas can then flow through these new pathways to the wellbore and be brought to the surface.
Comparing the Methods
Here's a simplified comparison:
| Feature | Conventional Drilling | Hydraulic Fracturing (Fracking) |
|---|---|---|
| Target Geology | Permeable reservoirs | Dense, impermeable rock (Shale, tight sands) |
| Extraction | Relies on natural flow/pressure | Artificially creates flow paths via fracturing |
| Fluid Injection | Typically not used for primary extraction | Essential for creating fractures |
| Well Paths | Primarily vertical | Often combines vertical and horizontal drilling |
| Hydrocarbon Type | Easily accessible | Tightly bound within the rock |
Implications and Applications
Conventional drilling has historically been the standard for accessing the most readily available oil and gas. However, many of these easily accessible reserves have been significantly depleted.
Fracking has opened up access to vast amounts of hydrocarbons contained in formations like shale, which were previously uneconomical or technically impossible to extract. This has dramatically increased potential recoverable reserves and reshaped the global energy landscape, particularly in countries with extensive shale deposits.
- Example: The widespread adoption of horizontal drilling combined with hydraulic fracturing in the United States in the early 21st century unlocked massive reserves in shale plays like the Permian Basin (oil and gas) and the Marcellus Shale (natural gas), leading to a significant boost in domestic production.
While both methods are critical to energy production, fracking generally involves a larger operational footprint, requires substantial volumes of water, and introduces different environmental management challenges related to fluid handling and potential seismic activity compared to traditional vertical drilling into permeable formations.
