How it Works
The enormous increase in our domestic oil and gas supplies from deep shale formations has been made possible by combining two proven and well-known technologies – horizontal drilling and hydraulic fracturing. The modern combination of these two technologies allows us to efficiently unlock vast supplies of oil and gas trapped in solid rock that were once thought to be inaccessible.
Horizontal drilling. With this technology, companies drill one vertical hole to the proper depth and then extend the wellbore out horizontally into several branches. This advancement significantly reduces the surface impact of drilling activities by providing access to more of the resource trapped in the formation underground using fewer wells above ground. This technology has reduced the average well site size by 30%, compared with wells drilled in the 1970s. This innovation provides access to 60 times more below-ground area, so companies recover even greater reserves with fewer wells while creating less surface disturbance and waste.
Hydraulic Fracturing. The other key technology in shale development is hydraulic fracturing – a process that has been performed in the U.S. more than 1.1 million times over the past 60 years. The general steps involved in the process of hydraulic fracturing are outlined below:
|1||Planning. The advanced process in use today involves creating a self-contained well system which is carefully planned and designed by geologists, engineers and geo-scientists using computer modeling to customize a well-stimulation design to optimize oil and gas recovery.|
|2||Deep Drilling. A deep well is drilled vertically, as deep as a mile (the equivalent depth of six Empire State Buildings, or more) – far below fresh water supplies – then steered horizontally into the shale formation.|
|3||Protective Casing. The wellbore is reinforced with multiple layers of protective steel encased in cement to completely seal off the process and protect water supplies.|
|4||Micro Fissures. After the well is pressure-tested to confirm its integrity, a mixture of water, sand and 0.5% percent of highly diluted additives are pumped through the secure wellbore at carefully controlled rates.|
|5||Sand Allows Release of Oil & Gas. The sand props open hairline cracks in rock, allowing the release and flow back to the surface of oil and gas through the secure wellbore, where it is collected.|
|6||Water Reuse. Fluid that is returned to the surface with the oil and gas is collected and either recycled for other operations or disposed of according to stringent state and federal regulations.|
It is important to note that The Environmental Protection Agency, Ground Water Protection Council, and the University of Texas have all examined the process and found it to be safe.