Simply Put - Why Compression Matters
It may be no surprise to some, but compression matters. One of the many challenges of natural gas production is that the reservoirs of natural gas typically exist in basins or offshore areas that are rarely where we need them most – our homes and businesses. To safely transport these resources to the areas that require them, we need to push the gas through pipelines over long distances. This requires pressure; creating high pressures necessitates the compression of the gas. But it’s not that simple; depending on the supply chain conditions, the level of compression will differ. Factors such as reservoir type, geographic location, the gathering network needed, and the type of well all play a role.
Compression is vital, but it’s not a one-size-fits-all equation. When you look at a fleet of compression units, each one may be completely different and have its own configuration, which means that they may not all be operating at their peak efficiency. However, the very definition of peak efficiency can change from site to site. For example, a compressor supporting a new well might aim for maximum flow and maximum suction, while a steady state well might prioritize maximum flow at the minimum suction possible. In contrast, a compressor supporting a process or gas lift might need a fixed flow rate without falling below a target suction pressure. As a result, some compressors may be inefficient, risk unplanned shutdowns, and fail to push the optimal amount of throughput. This “Compression Depression” is what we want to avoid, and this article will talk about how you can optimize your compression fleet with a few key concepts. This topic is also part of a webinar series we are hosting, which you can register for or watch previous episodes here: Know Pressure: Your Guide to Compressor Fleet Management
Symptom #1: Lower Utilization Lowers Production
Most of the time, a compressor is configured once during its initial setup and rarely reassessed. For a screw compressor, it may mean that the Volumetric Ratio (Vi), slide valve, and setpoints are configured the same since the asset was put in place. For a reciprocating compressor, it may mean the pockets, spacers, cylinder action, and setpoints have not been adjusted for months or years, even though the operating pressures are greatly different from the day it was put in place.
For example, if the pockets on a reciprocating compressor haven’t moved since the initial install, the cylinder utilization may be lower than optimal. A pocket setting of 4” (representing open pockets) on your first stage cylinders means your cylinder utilization is lower, leading to a higher suction pressure than necessary, which may reduce your well’s deliverability. Conversely, a pocket setting of 0” indicates 100% cylinder utilization, achieving the lowest possible suction pressure and potentially improving the deliverability of upstream wells. Our research shows that the total utilization of operating assets is 81%, with utilization measured as the greater of power utilization and cylinder utilization for each individual asset. This indicates that most assets are underutilized.
In our recent webinar, we talked about the concepts of runtime and utilization, and how one producer set out to improve the utilization of their equipment. This producer acted by adjusting set points, changing pockets, cylinder action, and employing various other low-cost techniques.
The Effect: Over a five-year period, they increased their compressor utilization from 84% to 91.5% through effective compressor fleet management. This increased utilization supported and contributed to 72 MMSCFD in added production.
Unsure what we mean by utilization and curious to know what they did? Check out the 1st episode of our Webinar Series here: Know Pressure: Your Guide to Compressor Fleet Management
Symptom #2: The Detriments of Excessive Bypassing
To protect the compressor and increase its runtime, most compressor skids are equipped with what is called a bypass valve. The bypass valve serves two purposes: protect the compressor and maintain suction pressure for upstream equipment. It works by drawing volumes of gas from the discharge lines and redirects it back into the suction line, hence bypassing the compressor.
When the bypass valve opens intermittently, a shutdown can be prevented, allowing the compressor to maintain service, preventing a trip from the operator or mechanic to start the machine, and possibly preventing a blowdown event where gas is vented to the atmosphere. All good things! However, if the bypass valve is open 24/7, it’s likely that the compressor is working harder than it needs to, resulting in higher power requirements from the driver. This increased power requirement means increased operating costs, more emissions, and more wear and tear. The great news is that compressors can be optimized to balance production requirements, runtime, and energy usage.
The Effect: When a bypass valve is open 24/7, the fuel or electricity usage of that asset can often be reduced by 25% through low-cost optimization techniques.
Symptom #3: Unnecessary Shutdowns Are Depressing and Costly
Let’s just call it what it is – shutdowns are not fun. They waste resources, time, and money, and can potentially impact your emissions. It’s just something you want to avoid, and unfortunately, it happens more often than you think. Based on a recent study conducted by Detechtion, it was identified that an average compressor shuts down 8 times/month and each event typically lasts for 8 hours. In some cases, shutdowns are necessary for preventative maintenance on both equipment and pipelines, but in other cases, shutdowns happen for unexpected reasons like pressures/temperatures outside of acceptable ranges, components failing, or other unforeseen issues.
What we’ve found is that several unplanned shutdowns can be prevented by taking two explicit actions. First, one of the most common reasons for a compressor shutting down is when the pressures exceed the low or high safety shutdowns. By continually monitoring and optimizing the compressor to operate within the typical and actual pressure range that the compressor is encountering, most shutdowns due to low or high pressures can be prevented. Secondly, components such as compressor valves fail all the time due to wear and tear. By monitoring the health of a compressor cylinder and the valves, and planning maintenance around their efficiency, a portion of unplanned downtime events can be converted to planned events.
The Effect: By taking these actions, compressor fleet operators will typically see at least a 1% increase in their assets' runtime.
Giving Your Compressors the Love They Need to Operate Efficiently
We talk about “Compression Depression” – and it’s a bit tongue-in-cheek, of course. But the reality is that there are actionable steps you can take to build out a series of actions and leverage technologies to gain more visibility and control over your entire fleet. Each unit is unique, and having a single source of truth and taking steps to Monitor, Control, and Optimize each unit will result in better throughput, lower energy consumption, fewer shutdowns (and improved failure prevention), and reduced ESG compliance risks.
By following our webinar series, you’ll gain insights into best practices for monitoring, optimizing, and managing your compressor fleet. Join us to learn how you can transform your operations and avoid “Compression Depression.” Register here for our series and start improving your compressor fleet management today!