Maximizing Reservoir Productivity: The Power of Hydraulic Fracturing

Hydraulic fracturing, commonly known as "fracking", is a process that injects high-pressure liquid into an oil- or gas-bearing rock formation to create fractures.

This pressure typically yields improved flows, making it useful for oil and gas firms seeking more economical production in areas that would otherwise produce low-flow wells.

Understanding Hydraulic Fracturing

Hydraulic fracturing involves pumping fuel into a wellbore to create enough pressure to develop and expand cracks in hard rock formations. The fluid injected into the well contains a combination of water, chemicals, and small particles of sand or ceramic materials.

The water and chemicals crack and open the rock through high pressure, while the solid particles, called proppant, stay in place and keep the fractures open to stimulate a better flow of liquids or gases out of the well.

History and Use of Hydraulic Fracturing

Hydraulic fracturing was first used in Kansas in 1947 in an attempt to extract natural gas from a limestone formation in the Hugoton gas field.

Since that time, petroleum engineers have regularly used hydraulic fracturing as a means of increasing well production. While fractures sometimes exist naturally in formations, both natural and human-made fractures can widen by this process.

Hydraulic fracturing is one of several technologies that make unconventional oil and gas plays economically more viable. Tight oil and gas reservoirs, including those embedded within shale formations such as the Bakken, Eagle Ford, Niobrara, and Pierre formations in North America, typically require a combination of horizontal drilling and hydraulic fracturing to produce efficiently.

How does fracking work?

It involves blasting fluid deep below the earth’s surface to crack sedimentary rock formations—this includes shale, sandstone, limestone, and carbonite—to unlock natural gas and crude oil reserves.

The process begins with the drilling of a long vertical or angled well that can extend a mile or more into the earth. As the well nears the rock formation where the natural gas or oil lies, drilling then gradually turns horizontal and extends as far as thousands of feet. Steel pipes called casings are inserted into the well, and the space between the rock and the casing is fully or partially filled with cement. Small holes are made in the casing with a perforating gun, or the well is constructed with pre-perforated pipe. Fracking fluid is then pumped in at a pressure high enough to create new fractures or open existing ones in the surrounding rock. This allows the oil or gas to flow to the surface for gathering, processing, and transportation, along with contaminated wastewater that is stored in pits and tanks or disposed of in underground wells.

Fracking equipment

Hydraulic fracturing requires an extensive amount of equipment, such as high-pressure, high-volume fracking pumps; blenders for fracking fluids; and storage tanks for water, sand, chemicals, and wastewater. This infrastructure, plus more, typically arrives at drill sites via heavy trucks.

What is in fracking fluid?

Made up of as much as 97 percent water, fracking fluid also contains chemical additives and proppants (small, solid particles used to keep the fractures in the rock formation open after the pressure from injection subsides).

Chemicals used in fracking

Different chemicals are added for different purposes, based on the rock type and other specifics of a fracking site. Acids, for example, are used to dissolve minerals to help fossil fuels flow more easily; biocides eliminate bacteria; gelling agents help carry proppants into fractures; and corrosion inhibitors prevent steel parts of the well from being damaged by fracking fluid.

Proppants used in fracking

Sand is the fracking industries' favored proppant, with high-purity quartz—known as “frac sand”—prized the most for its round shape, uniform size, and crush resistance. A single well operation can truck in thousands of tons of frac sand.

Environmental and Political Hydraulic Fracturing Controversy

Environmental concerns linked to hydraulic fracturing include air pollution from methane emissions, groundwater contamination, and the potential risk of induced earthquakes. The disposal of wastewater from the drilling process plays a primary role in many disagreements about how to weigh the technology’s risks against its benefits.

After drilling companies inject fluids into the well, the back-pressure from the rock formation generally pushes the mix of water and chemicals back to the surface through the wellbore. At that point, the fluids can be recycled or collected for eventual disposal. Drilling companies take precautions to ensure their wells do not leak either fracturing fluids or petroleum liquids into local water tables.

However, environmental groups have voiced concerns about contamination from inadequate holding tanks and spills. Some operations dispose of wastewater in deep wells, which has recently been correlated with an increased risk of earthquakes in Oklahoma.

Another problem linked to hydraulic fracturing is the leakage of methane gas from the fracking process.

These concerns have made the hydraulic fracturing process subject to strict regulation in some areas.