Fractured coal seam with glowing methane gas and interwoven tree roots.

Fracking Under Pressure: Unveiling the Truth About Hydraulic Fracturing of Coal

Samir D’Costa in Climate & Environment August 2025 • 4 min read.

"Is Hydraulic Fracturing the Key to Unlocking Coal's Energy Potential, or an Environmental Minefield?"

Hydraulic fracturing, or fracking, has become a pivotal technique in the production of coalbed methane. The method, which involves drilling into coal seams and injecting fluid to create fractures, aims to enhance gas production. But beyond the technical process, hydraulic fracking sparks complex questions about energy, environment, and economic impact.

The process typically begins with drilling into the coal seam and casing the gas well. A minifrac is performed to determine the hydrofracking parameters of the coal. Then, a calculated quantity of fluid—often water, gelled water, or cross-linked gel mixed with sand—is pumped into the well to create a fracture that can extend 500-1000 ft. Minifracs are small-scale versions of hydrofracking that offer insights into pressure, gradient, reservoir properties, and permeability.

While hydraulic fracking holds promise for increased energy production, it's essential to consider the environmental implications and debates surrounding the process. With the rising demand for energy and growing environmental awareness, hydraulic fracking sits at a pivotal intersection.

How Does Hydraulic Fracturing Work?

Fractured coal seam with glowing methane gas and interwoven tree roots.

The success of hydraulic fracking relies on several key stages, starting with identifying coal seams amenable to the process. These seams must meet specific criteria related to pore pressure and stress fields. Once a suitable seam is identified, a vertical borehole is drilled, typically extending about 200 ft below the target coal seam. A steel casing is then set just above the top of the coal seam.

Following the drilling phase, the coal seam undergoes a cleaning process known as hydrojetting. This involves using high-pressure water to remove any cement or debris that may obstruct the fracturing process. After cleaning, a small amount of water is pumped into the coal formation in a process called minifrac. This helps engineers monitor pressure decline and gather data to design the main fracking operation.

Water Fracture: Involves injecting water into coal at a medium depth.
Foam Fracture: Uses nitrogen foam for fracturing at a medium depth.
Slick Water Fracture: Applied to deep and thick coal seams, requiring a high rate of fluid flow.

The final stage involves pumping a precalculated amount of water mixed with sand into the coal formation. Under ideal conditions, the coal seam splits vertically, and the fracture extends bilaterally, often reaching lengths of 500-1000 ft. After the designed volumes of water and sand are pumped, the borehole is kept shut for a few hours before being flowed back slowly. While some gas production may be noted initially, the well is typically full of water and must be pumped to allow gas production to increase. The process ensures that the fracture remains open, allowing for sustained gas production, which can last from 5 to 20 years.

Fracking Moving Forward

Hydraulic fracturing is a method that can produce both economical and environmental effects. With an increasing energy demands from the population, it is important to analyze the environmental effects of fracking as well so better management of the method is implemented.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/b978-0-12-803095-0.00008-9, Alternate LINK

Title: Hydraulic Fracking Of Coal

Journal: Advanced Reservoir and Production Engineering for Coal Bed Methane

Publisher: Elsevier

Authors: Pramod Thakur

Published: 2017-01-01

Everything You Need To Know

What is hydraulic fracturing of coal, and how does it enhance gas production?

Hydraulic fracturing, often called fracking, is a technique used to extract coalbed methane. It involves drilling into coal seams and injecting a fluid, typically water mixed with sand, to create fractures in the coal. This fracturing process enhances the permeability of the coal seam, allowing the trapped methane gas to flow more freely and be extracted. A crucial aspect is the initial 'minifrac,' a small-scale hydrofracking operation used to gather data on pressure, gradient, and reservoir properties to optimize the main fracking operation.

What are the different types of hydraulic fracturing techniques used in coal seams, and how do they differ?

During hydraulic fracking, several types of fracturing techniques can be employed depending on the characteristics of the coal seams. These include 'water fracture,' which involves injecting water at a medium depth; 'foam fracture,' which uses nitrogen foam for fracturing, also at a medium depth; and 'slick water fracture,' which is applied to deep and thick coal seams and requires a high rate of fluid flow. Selecting the appropriate technique is critical for optimizing gas production while considering environmental factors.

What are the critical steps and considerations for the successful application of hydraulic fracturing in coal seams?

The success of hydraulic fracking hinges on several key factors, starting with identifying coal seams that meet specific criteria related to pore pressure and stress fields. A vertical borehole is drilled, followed by hydrojetting to clean the seam. A minifrac is then performed to gather data. Finally, water mixed with sand is pumped into the formation, splitting the coal seam vertically. The borehole is kept shut before being flowed back slowly. This process is designed to ensure the fracture remains open for sustained gas production, which can last for many years. However, the process is not without environmental impact, and its implementation requires careful planning and monitoring.

What environmental considerations and effects are associated with hydraulic fracturing, and why is analyzing them important?

While hydraulic fracturing can significantly increase energy production, environmental concerns exist. The environmental impact of fracking is not explicitly discussed. To move forward responsibly, it's crucial to analyze these environmental effects to better manage and mitigate potential harm. This includes implementing strategies for responsible water usage, waste disposal, and minimizing the risk of groundwater contamination. Further research and development in environmentally friendly fracking techniques are essential to balance energy demands with environmental protection.

How long can gas production last from a hydraulically fractured well, and what factors influence its longevity?

Hydraulic fracturing holds the potential for sustained gas production, potentially lasting from 5 to 20 years. This sustained production relies on the fractures created during the fracking process remaining open, facilitated by the proppant, typically sand, mixed with the injected water. However, the longevity of gas production can be influenced by factors such as reservoir characteristics, the effectiveness of the initial fracking operation, and ongoing maintenance of the well. It's also important to note that the initial phase after fracking involves pumping water out of the well to allow gas production to increase, which requires careful management of water resources.