Yesterday’s Video Tuesday post showed the construction of a wellpad site from start to finish. If you remember, the video featured a brief bit about hydraulic fracturing. Because we rely heavily on this process, we want to give you a more thorough explanation of how fracturing works.
We have all heard of “fracing” or “fracking,” but do we all understand what the process entails? I didn’t until I started my internship at Cabot Oil & Gas Corporation last week. Since then, I have surveyed plenty of industry professionals and have researched the process to give you the simple, “Drilling Down” bottom line about hydraulic fracturing. The drilling rig, or derrick, is constructed in approximately three days to penetrate the land vertically and eventually, horizontally. Drilling rigs are the Eiffel Tower-like structures that temporarily loom over wells. Over the next 14 days, drill operators work diligently to ensure that hydrocarbons cannot escape the well and land in underground sources of drinking water. To do so, they enforce the steel pipe lowered into the well with a cement casing that extends far below the water level.
FACT:More than three million pounds of steel and cement reinforce the average Marcellus Shale well.
FACT:Most Marcellus Shale sits 6,000 feet below the underground sources of drinking water, which is nearly half the height of the Empire State Building.
Once the vertical portion of the well reaches a point of approximately 500 feet above the Marcellus formation, drill operators manipulate a horizontal turn. In most cases, the horizontal drilling process allows for greater access to the Marcellus formation. Imagine a long wafer cookie with fruit filling. It would be more fruitful (pun intended) to eat the entire cookie than to take one bite out of the center, much like it is more fruitful to drill horizontally along the lengthy Marcellus Shale rather than through a shorter, vertical portion.
FACT:The distance of the horizontal well in either direction from its vertical source can range from 1,000 to 10,000 feet.
Now, remember how the well is encased in steel and cement? After drilling, engineers perforate that casing so that hydrocarbons can move into the wellbore. Perforation at this point is safe because the well is surrounded only by dense rock and Marcellus Shale. After strategically puncturing the pipeline, drilling equipment is removed and the process of hydraulic fracturing can begin.
FACT:Many of domestic wells would not be economical without the use of hydraulic fracturing to stimulate production from the well.
In the next three to 10 days, a lot of water, a lot of sand and a small amount of additives are forced by thousands of pounds of pressure into the pipeline. The force of the water, pushed through perforations into the Marcellus Shale, creates small “fractures.” Sand travels through these fractures and holds the cracks open so that previously trapped hydrocarbons can travel back to the wellbore. The sand, or “propant” literally props the fractures up so that space exists between fissures.
After the hydrocarbons flow into the perforations and up to the surface, they are collected for clean transportation, residential energy, industrial heating and much, much more. The hydraulic fluids are then collected for reuse and the well is prepared for production.
FACT: In the U.S. industrial sector, expanded use of domestically-produced natural gas in such applications as blast furnaces, power generation or “process” heat can reduce emissions, and reduce costs, making our nation’s manufacturers more competitive in the world market.
FACT:Though the process of hydraulic fracturing only takes a matter of weeks, the typical shale well can produce natural gas for decades.
Still confused? Check out Cabot Oil & Gas Corporation’s Natural Gas Facts or reference this interactive visual from Halliburton. Another great reference comes from FracFocus.org. If you have any additional questions about the hydraulic fracturing process or about Cabot’s efforts to fuel America with clean, domestic, natural resources, follow us on Twitter at @CabotOG and participate in #AskCabot Thursdays.
Samantha Scribner, External Affairs Intern for Cabot