In the first two parts of this three-part series on hydraulic fracking we discussed what hydraulic fracking is, its history, and the process of how it works. This final part of the series will cover how different well types utilize hydraulic fracking as well as the reasons and uses of hydraulic fracking.
What’s Hydraulic Fracking?
Hydraulic fracturing, also known as fracking, is a process used in the oil and gas industry to extract natural gas, oil, and even geothermal energy from deep underground. It involves injecting high-pressure fluid into a wellbore to create small fractures in the deep rock formations. These fractures then allow natural gas or oil to flow more freely, making it easier to extract.
Hydrofracking: What is it and How is it Different
Hydrofracking is another term for hydraulic fracturing. The term emphasizes the use of water (hydro) in the fracking process. The fluid injected into the wellbore is primarily composed of water, along with sand and certain chemicals. This fluid mixture is what creates the fractures in the rock.
Hydraulic Fracking vs Drilling: A Comparative Analysis
When it comes to extracting natural gas and oil from the Earth, there are two main methods: hydraulic fracturing and conventional drilling. Understanding the differences between these techniques is crucial for comprehending their technological, environmental, and economic effects.
Conventional Drilling
Conventional drilling is a traditional method that has been in use for more than a century. This technique involves:
- Drilling a well directly into an oil or gas reservoir trapped within permeable rocks, such as sandstone or limestone.
- Relying on the natural pressure of the reservoir to propel the oil or gas towards the surface. If required, pumps may assist in the extraction process.
Advantages: The primary advantage of conventional drilling is its relatively minimal environmental impact when compared to fracking.
Limitations: This method is confined to areas containing existing oil or gas reservoirs, which are increasingly dwindling.
Hydraulic Fracking
Hydraulic fracturing, or fracking, is a more recent technique, first implemented commercially in the mid-20th century. It is characterized by:
- Drilling a well vertically and then horizontally into the layer of rock containing the oil or gas.
- Injecting a high-pressure mixture of water, sand, and chemicals into the well, causing the rocks to fracture and release the trapped gas or oil.
Advantages: Fracking has significantly boosted the amount of recoverable oil and natural gas, prompting an energy boom in several countries, including the United States.
Limitations: This method has drawn substantial controversy due to its environmental implications, which include substantial water usage, potential contamination of groundwater from fracking fluids, and the risk of induced seismic activity (earthquakes).
Fracking vs. Drilling
Comparatively, fracking allows access to oil and gas deposits unreachable through conventional drilling. This ability has lengthened the lifespan of numerous oil and gas fields and rendered previously unprofitable fields economically viable.
Conversely, conventional drilling practices are often viewed as more environmentally friendly. These wells utilize less water, generate less wastewater, and carry a lower risk of triggering seismic activity.
Hydraulic fracking and conventional drilling have unique advantages and disadvantages. The selection between the two frequently depends on the particular geological attributes of an area, coupled with associated environmental and economic factors. Despite controversies, both techniques are predicted to maintain significant roles in global energy production until renewable energy sources become more widespread.
The Step-by-Step Process of Hydraulic Fracking
Site Preparation: The first step in the hydraulic fracking process is preparing the site. This involves clearing the area, setting up the necessary equipment, and ensuring all safety measures are in place.
Drilling the Well: Once the site is prepared, a well is drilled into the earth. This well often reaches several thousand feet deep, penetrating the rock formations where oil or gas is located. The drilling can be done vertically or horizontally, depending on the characteristics of the oil or gas reservoir.
Well Casing: After the well is drilled, it is encased with steel and cement. This casing is crucial for the protection of groundwater resources. It prevents fracking fluids and hydrocarbons from leaking into the surrounding environment.
Perforation: A perforating gun is then lowered into the wellbore to the desired depth. This tool is used to create holes in the casing and cement, providing a path for the fracking fluid to enter the rock formation.
Injection of Fracking Fluid: The next step is the injection of the fracking fluid. This fluid, composed mainly of water, sand, and a small percentage of chemicals, is pumped into the well at high pressure. The pressure of the fluid is strong enough to create fractures in the rock formation.
Fracture Propagation and Proppant Placement: As the fluid creates fractures in the rock, the sand in the fracking fluid, known as proppant, enters these fractures. The role of the proppant is to keep the fractures open once the injection pressure is released. This allows the gas or oil to flow freely.
Production: After the fracking process is completed, the pressure in the well is reduced, and the oil or gas begins to flow back to the surface. The well can now start producing oil or gas.
Flowback and Waste Management: The fluid that flows back to the surface, known as flowback, contains water and various chemicals. This fluid needs to be managed properly to prevent environmental contamination. It’s typically stored in tanks or pits on-site before being treated, recycled, or disposed of.
Essential Equipment for Hydraulic Fracturing
Hydraulic fracturing requires a range of equipment.
Frac Pumps: These are high-pressure, high-volume pumps used to inject the fracking fluid into the wellbore. They are designed to withstand the high pressures and abrasive materials involved in the fracking process.
Blenders: These are used to mix the fracking fluid. The blender mixes water, sand (or other proppants), and chemical additives to create the fracking fluid. The mixture is then sent to the frac pumps for injection into the well.
Proppant Transport Equipment: This equipment is used to transport the proppant (usually sand) that is mixed with the fracking fluid. The proppant is crucial in the fracking process as it helps keep the fractures in the rock open, allowing oil or gas to flow out.
Monitoring Equipment: Various types of monitoring equipment are used to ensure the fracking process is carried out safely and efficiently. This includes pressure monitors, flow meters, and data acquisition systems. These tools help operators monitor the fracking process in real-time and make necessary adjustments.
Frac Tanks: These are large storage tanks used to hold the water and fracking fluid before it’s injected into the well. They are designed to withstand the harsh conditions of the fracking site and can hold thousands of gallons of fluid.
Manifolds: These are used to control the pressure and direction of the fracking fluid. They allow operators to control the flow of fluid from the frac pumps to the wellhead.
Wellhead: This is the component at the surface of the well where the fracking fluid is injected. It includes various valves and seals to control and monitor the injection process.
Hydraulic Fracturing Units: These are large trucks that house the frac pumps, blenders, and other equipment. They are mobile and can be moved from one fracking site to another.
Understanding the Functionality of a Hydraulic Frac Pump
A hydraulic frac or fracking pump is a high-pressure, high-volume pump. Its primary role is to inject the fracking fluid into the wellbore, a task that requires both power and resilience.
The frac pump is designed to handle the harsh conditions of the fracking process. It must withstand high pressures, abrasive materials such as sand, and corrosive chemicals. To achieve this, hydraulic frac pumps are typically constructed from robust materials and are lined with special coatings to resist wear and tear.
Powering these pumps are typically diesel engines or electric motors, providing the necessary force to achieve the high pressures and volumes required for fracking. The pump operates in multiple stages, each one increasing the pressure of the fracking fluid. As the fluid passes through each stage, the pressure incrementally increases until it reaches the level required to create fractures in the rock formation.
Modern frac pumps often come equipped with sophisticated control systems. These systems continuously monitor the pump’s performance, making necessary adjustments to optimize the fracking process. This could involve changing the pump speed, pressure, or volume based on real-time data.
Maintenance and safety are also paramount when it comes to frac pump operations. Regular inspections, part replacements, and vigilant monitoring for potential problems help ensure the pump operates reliably and safely. Safety measures can include pressure relief valves and emergency shutdown systems, providing crucial protection for both the pump and its operators.
Hydraulic Fracturing Fluids: Composition and Function
Hydraulic fracturing, or fracking, is a process that involves the use of a specific fluid, known as fracking fluid. This fluid plays a crucial role in the fracking process, and its composition is carefully designed to maximize efficiency and safety.
Composition of Fracking Fluid
The fracking fluid is primarily composed of three main components: water, proppants (usually sand), and chemical additives.
Water: Water is the main component of fracking fluid, making up about 90% of its composition. It serves as the base fluid and is responsible for carrying the proppants and chemical additives into the wellbore. The high-pressure water also creates the fractures in the rock formation.
Proppants: Proppants, such as sand, make up about 9.5% of the fracking fluid. These small, solid particles are carried by the water into the fractures created in the rock. Once inside the fractures, the proppants remain behind when the pressure is released, keeping the fractures open and allowing oil or gas to flow out.
Chemical Additives: The remaining 0.5% of the fracking fluid is composed of various chemical additives. While they make up a small percentage of the fluid, these chemicals serve important functions in the fracking process.
Function of Chemical Additives
The chemical additives in fracking fluid serve various functions, each designed to improve the efficiency of the fracking process or to protect the well and equipment. Here are a few examples:
Friction Reducers: These chemicals reduce the friction of the fluid as it’s pumped into the well. This allows the fluid to be pumped at a higher rate and pressure, which is crucial for creating fractures in the rock.
Biocides: Biocides are used to prevent the growth of bacteria in the well. Bacteria can produce substances that can damage the well and equipment, or reduce the flow of oil or gas.
pH Adjusters: These chemicals are used to control the pH of the fluid. Maintaining the right pH is important for the effectiveness of other chemical additives and for preventing damage to the well and equipment.
Hydraulic Fracking for Different Types of Wells
The pressure, flow rate, and composition of fracking fluids used for hydraulic fracking will vary from well to well. Wells might be classified according to one of the following criteria:
Vertical Versus Horizontal Wells
Vertical Wells – Verticals wells are the traditional type of oil or gas well that go straight down, typically to a depth of about 50-300 feet. These wells penetrate perpendicular to the rock layer containing the oil or gas reserve. Hydraulic fracking on vertical wells is commonly used for “well stimulation” to increase the efficiency and output of the well. Compared to horizontal well fracking, this type of fracking requires lower pressure and volume.
Horizontal Wells – Horizontal wells terminate with the wellbore parallel to the rock layer containing the oil or gas reserve. Horizontal wells also reach a much deeper depth than vertical wells. For example horizontal wells drilled in the Barnett Shale Basin in Texas goes down between about 1,500 to 5,000 feet, while the horizontal wells drilled in the Bakken Shale Formation in North Dakota go down to up to 10,000 feet. Due to the higher pressure associated with these depths hydraulic fracking must be done at a much higher pressure and volume.
High-Rate Versus High-Viscosity Fracking
Fracking may also be done using either a high rate of pumping to deliver the proppant or a high-viscosity slurry. Each fracking method will yield slightly different results.
High-Rate Fracking – High-rate fracking uses a high rate of pumping to deliver the proppant. This is the type of fracking associated with slickwater fracking fluids because the reduced friction allows the fluids to be pumped more quickly, at a higher rate. This type of fracking generally causes a network of small, spread out micro-fractures.
High-Viscosity Fracking – High-viscosity fracking uses higher fluid viscosity as its means of effectively the proppant. High-viscosity fracturing tends to be characterized by larger, more dominant fractures.
Controlling Leakoff During Hydraulic Fracking
Another consideration with hydraulic fracking is leakoff. Leakoff refers to the loss of fracturing fluid whereby instead of going into the fracture channel it seeps into surrounding permeable rocks. If leakoff is not properly controlled a very high rate (over 70%) of fracking fluid volume can be lost. Leakoff may adversely affect production efficiency by damaging the formation matrix, harming formation fluid interactions, or altering the fracture geometry.
The Reasons for Hydraulic Fracking
Hydraulic fracking offers several advantages for oil and gas recovery including:
Increased Accessibility – Hydraulic fracking offers a huge benefit by radically increasing the amount of oil and gas that can be extracted from deep-level rock formations. In most cases it would not be economic or even feasible to recover the oil and gas found in these very deep formations with extremely low natural permeability.
Greater Efficiency – As discussed above, hydraulic fracking can be used to stimulate and improve well production. This allows the oil or gas to be recovered more efficiently and at higher rates.
Lower Costs – Due to the advantages of greater accessibility and efficiency, hydraulic fracking also creates an overall better economy for the oil and gas industry, allowing companies to reap greater amounts of product at lower costs, continue operating a well for longer, or even re-open a well that may have previously been considered dried up.
Other Uses for Hydraulic Fracking
Though the main focus of this article has been on the role hydraulic fracking plays in the oil and gas industry, it offers other additional benefits and applications such as:
Water Wells – Just as hydraulic fracking is used to increase the rate and efficiency of recovery for oil and gas, it can also be used to stimulate groundwater wells. This technique has successfully been done not only in the US, but also in Australia and South Africa.
Mining Applications – Hydraulic fracking also has mining applications where it can be used to induce controlled rock caving. It has also been proposed for uranium mining in which it will be used to inject substances that will dissolve the uranium so that it can then be pumped to the surface.
Energy – Hydraulic fracking is used in geothermal systems to enhance heat extraction and produce electricity.
Waste – Hydraulic fracking is used in waste remediation processes, to dispose of waste by injecting it into deep rock formations, and for geologic sequestration of carbon dioxide.
Measurement – Hydraulic fracking can be used by geologists to measures stress levels within the Earth.
Hydraulic fracking is used extensively across multiple areas of focus and industries in the US as well as globally. As hydraulic fracking technology advances, it is likely to become applicable in currently unforeseen ways. In addition to fracking, the leading hydraulic fracking companies in the Oil & Gas industry as a whole will continue to innovate and create new processes and methodology to produce fuel sources for the world’s consumption.
