Introduction

Natural gas compressors are crucial to the energy sector, particularly in transporting and processing natural gas. These devices ensure that natural gas, extracted from low-pressure wells deep underground or offshore, is efficiently transported to gathering systems, power plants, homes, and industries. They maintain a constant pressure despite fluctuations in production reservoir pressure, enabling the gas to travel long distances. Often referred to as compressor stations, these systems are integral to the gas delivery network, utilizing multiple compressors throughout transit. They form a key part of the natural gas pipeline network, moving gas from individual well sites to end users. As natural gas travels through pipelines, factors like friction, distance and elevation changes slow its movement and decrease pressure. Strategically placed compressor stations within the network maintain the necessary pressure and ensures the flow of gas gets to consumers.

This article delves into the mechanics of natural gas compressors, their widespread applications, pertinent industry statistics, and trends within the United States.

Function of Natural Gas Compressors

Natural gas compressors are vital devices that increase the pressure of natural gas, ensuring its efficient transport through pipelines. These compressors serve multiple purposes: they enable the long-distance conveyance of natural gas, support the extraction from low-pressure wells, stabilize pipeline pressure despite fluctuations, and extend the lifespan of nearly depleted gas and oil wells by lowering wellhead pressure. By drawing in low-pressure gas and using pistons or rotary mechanisms, these compressors elevate the gas pressure to levels suitable for transportation.

In the natural gas industry, two primary types of compressors are used: positive displacement compressors and dynamic compressors. Positive displacement compressors work by mechanically reducing the gas volume to increase its pressure. They capture a specific amount of gas in a chamber and compress it by decreasing the chamber’s size. Examples include reciprocating piston compressors, rotary screw compressors, rotary vane compressors, and scroll compressors. On the other hand, dynamic compressors, such as centrifugal (radial) compressors, axial compressors, and mixed-flow compressors, use high-speed rotating blades to accelerate and decelerate the gas, thereby raising its pressure through dynamic action. For addition distinctions between these types of compressor, look for our upcoming post, Types of Gas Compressors.

At compressor stations, natural gas first undergoes treatment with scrubbers and filters to remove liquids and solids. Once purified, the gas is directed to one or more compressors. Computer systems control the flow and the number of operational units to meet the system’s flow requirements. Most compressor units operate in parallel, providing the necessary pressure boost before the gas is returned to the pipeline at full operational pressure. When a substantial pressure increase is needed, multiple compressor units may operate in stages to achieve the desired pressure incrementally.

Compressing natural gas generates heat, which must be dissipated to cool the gas stream before it leaves the compressor facility. Most compressor stations use aerial cooler systems, also known as aftercoolers, to dissipate this excess heat. The heat generated by individual compressor units is managed by heat radiating devices similar to automotive radiators.

In areas producing wet gas or natural gas liquids, pressure and temperature changes cause some liquids to condense and drop out. These liquids are collected in tanks and transported off-site. The captured liquids, referred to as natural gasoline or drip gas, are often used as a blend in motor gasoline.

Most compressor stations are powered by a portion of the natural gas flowing through the station. However, in some areas, units may be electrically powered for environmental or security reasons. Gas-powered compressors can be driven by conventional piston engines or natural gas turbine units, each with unique designs, operational characteristics, and specific air and sound emissions.

Compressor stations may house one or more individual compressor units, which can be located outdoors or, more commonly, inside buildings to facilitate maintenance and manage sound. Newer units are often housed individually, but multiple units may be placed within a single large building. These buildings typically feature insulated walls, shielded exhaust systems, and advanced fan technology to reduce noise. In regions where noise regulations are stringent, newly constructed compressor buildings incorporate sound-dampening features.

Wellhead Applications Of Natural Gas Compressors

In natural gas wells, wellhead compressor systems increase gas velocity, preventing pressure drops at the borehole’s bottom and eliminating production constraints due to liquid loading. In oil wells, these units reduce pipe pressure and minimize backpressure, which can hinder production. This also eliminates air entrapment issues and enhances the pump’s delivery rate.

When mature gas and oil wells experience declining production, gas compressors can recover substantial remaining assets. Conventional extraction methods become insufficient, and increasing gas pressure aids in transporting produced gases or liquids upwards through the production tubing. By introducing compression, wellhead pressure is reduced, enabling larger gas flow rates. Wellhead compression places a compressor over the well, reducing back pressure and boosting output.

A typical wellhead system may use either small, individual compressors or large central units handling multiple wells or an entire field. Compressors can range from five horsepower to several thousand horsepower, though most are around 200 hp. These compressors need to be cost-effective and highly reliable. The closer the compressor is to the wellhead, the higher the likelihood of gas saturation with liquids, necessitating field units designed to tolerate some liquid presence. Reciprocating compressors are generally preferred for wellhead gas compression, but rotary positive displacement units can also be used in cases of significant low-pressure issues.

Other Applications of Natural Gas Compressors

Beyond wellhead applications, natural gas compressors are crucial across other phases of gas handling and distribution:

  • Processing Plants: Before transportation, natural gas must be processed and purified, which often involves compression.
  • Storage: Compressors are used to inject gas into underground storage facilities and to withdraw it when needed.
  • Transportation: Compressors at regular intervals along pipelines maintain the gas flow and pressure over long distances.
  • Distribution: In urban distribution networks, these compressors regulate the supply of gas to meet residential and commercial demand.

Industry Statistics and Trends in the United States

The United States is one of the largest producers and consumers of natural gas, and the infrastructure for gas compression is extensive and well-developed. According to the U.S. Energy Information Administration (EIA), the U.S. consumed approximately 30.5 trillion cubic feet of natural gas in 2022, with the production sector continuously evolving to meet this demand.

The compressor market in the U.S. is integral to this growth, with numerous large-scale projects underway to expand and upgrade pipeline networks. As per industry reports, the U.S. natural gas compressor market is projected to grow significantly, driven by increasing natural gas exploration activities and the need for enhanced pipeline infrastructure.

Key Industry Players in Natural Gas Compressor Components

The market for natural gas compressor components is supported by a host of specialized companies, each contributing to various aspects of compressor technology. Prominent among these are companies like Siemens Energy, Atlas Copco, and Ingersoll Rand, which are known for their expertise in manufacturing high-quality compressors and compressor parts. These companies supply a range of products from complete compressor units to critical parts like valves, seals, and control systems.

Baker Hughes and Schlumberger, primarily recognized for their roles in oil and gas exploration, also provide specialized compression equipment tailored for the natural gas sector. Their products are essential for applications requiring high durability and precision under challenging operational conditions.

Additionally, companies such as Solar Turbines (a subsidiary of Caterpillar) specialize in producing gas turbine-driven compressors, which are particularly suited for applications where reliability and high throughput are paramount. These companies not only manufacture equipment but often provide comprehensive maintenance and service packages to ensure optimal performance over the compressor’s lifecycle.

This network of companies plays a crucial role in the development and distribution of natural gas compressors, driving innovation and ensuring the reliability of gas supply systems across the globe. Their ongoing research and development efforts are crucial for meeting future energy demands while minimizing environmental impacts.

Historical and Future Trends

Historically, the evolution of natural gas compressors has mirrored advancements in technology and shifts in energy policy. Initially, the focus was on volume and capacity, but recent trends emphasize efficiency, environmental impact, and reliability. The shift towards greener technologies is evident in the development of electric-driven compressors, which reduce greenhouse gas emissions compared to traditional gas-driven units.

Looking ahead, the industry is likely to see further innovations aimed at reducing environmental impact and enhancing operational efficiencies. The integration of digital technologies, such as predictive maintenance and smart monitoring systems, is set to improve the reliability and performance of natural gas compressors.

Conclusion

Natural gas compressors are indispensable to the energy sector, facilitating the efficient and effective transportation and storage of natural gas. As the industry evolves, these compressors will continue to adapt, incorporating advanced technologies to meet the demands of a dynamic energy landscape. The ongoing developments in the U.S. compressor market reflect a robust commitment to meeting the energy needs of tomorrow while addressing the critical challenges of energy efficiency and environmental sustainability.