A Description of Hydraulic Fracturing For the Layman
According to The Daily Reckoning, a publication by Bill Bonner and Addison Wiggin, buried beneath the surface of United States soil there are 1.5 trillion barrels of shale oil. This is more than five times the stated reserves of Saudi Arabia.
In addition to shale oil, natural gas is another source of energy waiting to be extracted. A report released in April of 2011 by the Potential Gas Committee, states that there are 2,170 trillion cubic feet of natural gas hidden in the earth, within the boundaries of the US.
These natural resources below the earth’s surface are capable of providing us many decades of energy with which to fuel our transportation system and heat our homes. The question is, how do we access this gold mine?
So far, hydraulic fracturing seems to be the best solution for pulling to the surface the vast stores of oil and natural gas trapped under our feet.
Fracturing, also known as fracking, is not a new concept. A form of today’s fracturing was practiced all the way back in the 1860s when liquid and solidified nitroglycerine were used to stimulate shallow, hard rock wells in Pennsylvania, New York, Kentucky and West Virginia.
This hazardous and often illegal method of extracting oil and natural gas from the earth was quite successful.
In 1930 the dangerous explosives used to break up hard rock in order to obtain gas and oil were replaced with a non-explosive fluid (acid) which was injected into wells. Known as “pressure parting”, the acid created fractures that would not close completely, making it possible to withdraw oil and natural gas from hard rock.
In the 1940s the hydraulic fracturing process, also known as hydrafrac, began to be developed and after much experimentation, a patent was issued by Halliburton Oil Well Cementing Company (HOWCO) and the first two commercial fracturing treatments were produced.
It wasn’t until the early 2000s that the first modern fracking technique, called horizontal slick water fracking, made the extraction of shale gas economical. This process occurred in the Texas Barnett Shale.
This Is How Hydraulic Fracturing Works…
A wellbore is drilled using a drill pipe and bit.
Mud is pumped down to the drill to cool and lubricate the drill pipe and bit.
The mud helps stabilize the wellbore and helps carry rock fragments to the surface.
Drilling continues way past groundwater levels.
Thousands of feet of rock separate shale reserves from the lowest groundwater reservoirs.
The drill pipe and bit are removed.
A steel tube called surface casing is set inside the well.
The tube stabilizes the sides of the well creating a protective barrier between the well stream and any underground fresh water reservoirs.
Cement is pumped into the well through and out of the casing, displacing remaining drilling fluids and securing the casing in place permanently.
Filling the gap between the casing and wellbore cement creates a protective seal, keeping outside materials from entering the well flow.
Casing is pressure tested to make sure hydrocarbons and other fluids do not seep out as they are brought to the surface.
Pipe and drill bit are lowered back into the well where drilling continues.
Another layer of casing and cement are set in place to create a second permanent protective barrier,
Multiple layers of casing and cement are critical for safe well construction and to protect drinking water.
About 500 feet above hydrocarbon shale formation a specific drilling motor with sophisticated measuring instruments begins drilling at an angle to create a horizontal path to penetrate the targeted layer of gas or oil bearing shale.
Casing and cementing process continues through the entire length of the now horizontal wellbore.
A perforating tool is inserted into the well, creating holes in shale layers, allowing hydrocarbons to enter the well stream.
The perforating tool is removed.
A fracturing fluid made up of water and sand and a very small percentage of a chemical solution is pumped into the well, opening up tiny fractures deep into the shale.
The water is removed. The sand remains, holding the fractures open, making it possible for gas or oil to travel from the shale out into the well.
Bridge plugs are inserted, allowing the fracturing process to continue across the whole length of the horizontal well.
After the fracturing process is completed the bridge plugs are removed, allowing the gas or oil to flow freely to the surface.
The time spent on the actual hydraulic fracturing is brief compared to the lifetime of the well. On average it takes four to eight weeks to prepare a site for drilling. Then there’s another four to five weeks of rig work where the casing and cementing occurs.
Hydraulic fracturing only takes from two to five days, making the entire process from start to finish a total of seventy to a hundred days for a well that can produce energy for 20 to 50 years. Trucks, pumps and equipment are removed.
The production valve and collection equipment are all that’s left behind, leaving a minimal footprint on the land.
Each well is different. Each well presents its own problems. Oil and gas companies learn and correct flaws with each new well, making hydraulic fracturing the cleanest, most economical method of extracting America’s energy sources hidden deep within the earth.
Coming up next, read about some fracking problems and solutions.