What Is Hydraulic Fracturing? – Fracking Process Steps
September 3, 2019 Welcome
Hydraulic fracturing is one of the most effective techniques for recovering unconventional oil and gas resources. The plunge in oil prices between 2014 and 2016 was partly an aftereffect of extensive hydraulic fracturing production in U.S. shale plays which ramped up the overall volume of crude worldwide and caused an oversupply.
However, the hydraulic fracturing method is not new; operators in the U.S. have employed it since 1949. In this article, we will discuss what hydraulic fracturing is and examine the technicalities involved.
What Is Hydraulic Fracturing?
Hydraulic fracturing, also known as fracking, is a well stimulation technique where a high-pressure fluid is injected into a reservoir to fracture a hydrocarbon-bearing rock, causing a flow of oil and gas to the surface.
Fracking fluid may be a mixture of water, fine-grained silica sand, and special chemicals capable of creating fissures in underlying rocks. According to the U.S. Department of Energy, 95% of new oil and gas wells in the country are exploited using fracking techniques which accounts for over 60% of the total volume of U.S. marketed natural gas and 50% of total U.S. crude production.
Why Is Hydraulic Fracturing Done?
Fracking is the most effective technique for hydrocarbon recovery in challenging oil and gas fields where unconventional drilling techniques are needed to achieve target production volumes. Formations having crude or gas-saturated rocks with low permeability and poor water-oil connectivity are prime examples.
When and Where is Hydraulic Fracturing Done?
The fracking process is carried out after Completions have been done on a drilled hole. It is employed as an enhanced oil recovery (EOR) technique in unconventional reservoirs such as shale, tight oil and tight gas.
For example, from Eagle Ford (Texas) to Woodford (Oklahoma) and Monterey (California), fracking alongside horizontal drilling operations have been used to recover up to 70% of oil initially in place (OIIP) of shale and tight oil.
Depth of Hydraulic Fracturing
Natural gas hydraulic fracturing and oil-bearing rock fracturing is done at great depths. A typical hydraulic fracturing well depth can range from 7,000 – 10,000 feet underground.
At a certain depth into the wellbore, the well extends into the formation horizontally (called the kick-off point). Hydraulic fracturing must be carried out at enough depth to bypass water tables for public or industrial use. This consideration is critical for preventing contamination from toxic chemicals.
Extracting Shale Gas
To extract natural gas from shale using the hydraulic fracturing process, high-pressure frac fluid is injected into the reservoir which creates fissures in the shale formations. As individual fissures connect, the gas pools together from several sections within the rock. It is then tapped off via the production casing.
Coalbed Methane Production
Coalbed methane (CBM) is a form of natural gas produced from coal beds. In the U.S. it is increasingly being used as an alternative energy source and for heating purposes. Coal beds are porous subsurface structures containing methane gas of varying amounts trapped in natural fractures.
Hydraulic fracturing can be used to increase the number and connectivity of individual fissures, allowing operators to tap off the gas more efficiently.
Tight Sand Gas Production
Hydraulic fracturing can be employed to recover hydrocarbons from tight sand gas reservoirs. These are low-permeability reservoirs that contain mostly dry natural gas. Fracking operations (explained in a subsequent section) can help improve the mobility of gas through these reservoirs and speed up the recovery process.
Typically, the fracturing is done after a vertical or horizontal well has been drilled, completed, and perforated. Using the best technology, fracking can recover up to 70% of Original Gas in Place (OGIP) in tight gas formations.
Chemical Injection vs. Hydraulic Fracturing
Chemical injection is a similar well stimulation technique that uses special chemicals such as long-chain polymers (alkaline or micellar substances) to improve the oil recovery factor. A chemical injection skid can be used alongside other EOR techniques such as oil and gas water injection.
The chemicals improve hydrocarbon mobility by reducing the interfacial tension between the oil molecules and water present in the reservoir. Fracking is safer and more efficient than chemical injection.
Hydraulic Fracturing Process Steps
The basic hydraulic fracturing steps include the following:
- Drilling and Completions: A well is drilled, and the wellbore completed.
- Perforation: Perforations are made at a suitable depth along the horizontal production casing, also known as pay zones.
- Injection: Fracking fluid is injected into the reservoir at very high pressures, which creates fissures in hydrocarbon-bearing rocks and releases the products.
Trust IFS Modular Process Skids for Hydraulic Fracturing Support
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To request a quote or speak with an IFS professional, please contact us online today!