Mechanics of Fracking (Technical Explanation)

Fracking is a technical process that occurs over a mile beneath the surface to access shale oil that would otherwise be unable to be extracted. In this process, the goal is to fracture the rock and release a pressurized liquid into it in order to allow for the oil to be extracted. Initially, a drill pipe is inserted into the land and drilled vertically over a mile beneath the surface, this deep depth is necessary in order to not disrupt anything occurring on the surface. After the hole is drilled a steel pipe is inserted and concrete is pumped all the way to the bottom of the well and then in excess so that it forms around the casing and creates a wall that will not allow groundwater or soil to pass through. This is to ensure that groundwater supply is not affected in nearby areas. Drilling for hydrocarbons in a shale formation is different because you need to drill horizontally in addition to the standard vertical drilling. To drill horizontally the pressure of the injection must be greater than the total pressure of the overburden. It’s necessary for horizontal drilling that a place with deformed rocks and proper tectonic compression is selected for the placement of a fracking pad. Once the vertical drilling stops the drill bit starts curving and drills horizontally. The same process is repeated with the steel casing being inserted and concrete barrier solidified in place. A perforating gun is lowered into the casing and fired off near the reservoir rock to crack the rock and create spacing. Stimulation fluid referred to as frack fluid, is pumped down into the well where the perforating gun created the initial separation of rock and injects a mixture of sand, water, and chemicals into the rock. The sand is used to enter the “veins” created by the perforating gun and act to prop them open for the actual oil extraction. The list of chemicals used in fracking has always been controversial. Chemical Abstract Service numbers are assigned to various chemicals to give them a designation of their composition for research and general knowledge purposes. One of the issues with the lack of regulations on fracking is that only about two-thirds of the chemicals used are disclosed and have a CAS number attached to them, there is currently about 353 chemicals that the public is informed on. Most of the chemicals are used for the purpose of the stabilizing and lubricating the well. Methanol and Ethylene Glycol as lubricants to reduce friction in the steel casing. They also use chemicals like Acetaldehyde and Isopropanol to prevent corrosion of the steel casing and the drill bit. The process of fracturing occurs along the entire horizontally drilled area and about 15–50% of the frack fluid gets recovered for reuse or disposal. The released gas and oil are then able to flow into the horizontal wells and into storage tanks that await on the surface. In some cases, Lauryl Sulfate is used to increase viscosity in the oil to improve flowing. After the well is complete all machinery on the surface is removed and the well is filled up with concrete and grass, trees, et cetera can be planted and it will return to its previous state of land.

References

http://archives.datapages.com.libproxy1.usc.edu/data/specpubs/methodo2/images/a075/a0750001/0200/02390.pdf

https://fracfocus.org/chemical-use/what-chemicals-are-used

One clap, two clap, three clap, forty?

By clapping more or less, you can signal to us which stories really stand out.