An expanding global demand and expanding domestic energy reserves have fueled renewed interest in America’s oil and gas business.
With a growing distaste for our dependence on foreign sources of oil, companies both large and small are scrambling to find domestic reserves in commercial quantities.
This aggressive approach has led companies to search for and produce oil and natural gas, hydrocarbons, in locations previously considered too close to residential and commercial development.
And while exploration companies generally go the extra mile to accommodate – and appease – affected landowners, one issue has proven more challenging than most: NOISE.
From a landowner’s perspective, the quest for hydrocarbons involves three primary activities:
1. Geologic / Seismic
This phase involves the gathering of scientific data that helps geologists determine whether or not there are sufficient hydrocarbons under ground to pursue drilling at any given location.
Most of the geologic work is done on computer, far away from the actual property. But seismic testing, if required, is done on site and often involves some heavy equipment and specialized vehicles.
This testing normally only takes a matter of days and emanates little noise, so the intrusion for the landowner is minimal.
Once the geologic data has confirmed the presence of hydrocarbons, the exact location of the well is selected and staked on the property. Access roads and a drilling site are prepared for the arrival of the drilling rig.
Then the rig itself, and all its ancillary equipment, is moved onto the location. For the next several weeks (or months, pending the target depth of the well), the rig will be drilling the well.
This process runs 24-hour per day, and involves equipment that emanates substantial noise.
Since this is viewed as a temporary activity, landowners often tolerate the inconvenience without mandating any type of noise attenuation effort from the company. In some cases, however, such noise must be addressed. In these situations, the use of a temporary or portable noise screens is the most effective treatment.
“The gas compression process produces very high noise levels.”
3. Hydrocarbon Production
If the well discovers commercial quantities of hydrocarbon, the rig is removed and replaced with production equipment that will extract the hydrocarbon from the ground, and either store it in tanks or transport it via pipeline.
In the case of oil production, it is a fairly quiet process. Today’s modern pump-jacks are much quieter than their predecessors.
In the case of natural gas production, however, noise is a formidable problem. Natural gas must be treated and compressed before entering pipelines, and the natural gas compression process produces very high noise levels.
Since these compression systems may be continually running on site for many years, mitigating their noise is a high priority – for landowners and, subsequently, for the production companies.
How Do Production Companies Reduce Compressor Noise?
Natural gas compressor stations can range from very small units to behemoth systems exceeding 5000 hp. These systems incorporate a sophisticated, finely tuned combination of components – each generating a unique noise profile.
The manufacturers of these components have spent considerable intellectual and financial capital designing and redesigning their equipment to minimize noise.
Additionally, there are ancillary products that effectively reduce noise, including high-performance muffler systems, and acoustic baffling and wraps. In combination, these treatments considerably reduce the combined noise level of the system.
However, even the most highly attenuated compression systems emanate dangerously high noise levels that need additional treatment.
Intuitively, the noise generated is somewhat proportionate to the size, with noise levels in excess of 115 dBA. Such high levels are considered dangerous to humans without ear protection.
Since this equipment is located outdoors and can be immense in physical size, reducing or attenuating its noise poses unique problems.
Primary Noise Treatments
Today, there are two primary sound attenuation panels techniques widely used for compressor systems. One involves a fully enclosed, sound-attenuated building.
The other involves a high-performance, sound-absorptive peripheral noise barrier. Both designs are extremely effective at mitigating noise, but there are significant differences between the two.
1. Attenuated Full Enclosures
When designed and installed properly, attenuated sound enclosures incorporate several beneficial features. They provide the highest level of overall noise elimination available. Being enclosed, they also provide protection from the elements.
However, there are drawbacks as well. These facilities are expensive, often costing upwards of $1 million once installed. The enclosures require massive ventilation systems to prevent heat-and gas buildup; these ventilation systems are expensive to purchase and operate. They also require redundant, explosion-proof electrical and monitoring systems.
“In the majority of situations, a high-performance peripheral sound wall will provide ample attenuation for less cost and fewer moving parts.”
2. Peripheral Absorptive Noise Barriers
Alternatively, a high-performance absorptive noise barrier also boasts some key features. They provide excellent noise elimination, providing only slightly less attenuation than full enclosures.
Having no roof, they do not require expensive mechanical ventilation systems, nor do they create gas or heat-buildup. And they are considerably less expensive than full enclosures.
Potential drawbacks would include slightly inferior attenuation compared to full enclosures, as well as the lack of protection from the elements.
How Much Noise Is Reduced?
From the landowner’s perspective, the impact of such noise attenuation barriers measure is immediate and substantial. Generally, overall noise is reduced by 15-20 dBA at the source, and 10-15 dBA at distance.
In some cases noise levels are reduced even more. To the human ear, this equates to a perceived audible reduction of 75-90%, which is usually sufficient to appease most landowners.
“This equates to a perceived audible reduction of 75-95%.”
Which Option Is Best?
The short answer is “both“.
There are hypersensitive situations that simply must have the maximum possible level of noise reduction panels, regardless of the cost. In such instances, the fully attenuated enclosure is the only option.
In the majority of situations, however, a high-performance peripheral sound wall will provide ample attenuation for less cost and fewer moving parts.
The good news is there are products available – in both classifications – with proven effectiveness in the oil and gas business.
Both provide meaningful noise reduction, both are aesthetically acceptable, and both provide a welcome solution for production companies and affected landowners alike.
Measuring Noise: How much is too much?
Noise intensity is measured in decibel units (dBA). The dBA scale is logarithmic; each 10-dBA increase represents a tenfold increase in noise intensity.
Human perception of loudness also conforms to a logarithmic scale; a 10-dBA increase is perceived as roughly a doubling of loudness.
Thus, 30 dBA is 10 times more intense than 20 dBA and sounds twice as loud; 40 dBA is 100 times more intense than 20 and sounds 4 times as loud; 80 dBA is 1 million times more intense than 20 and sounds 64 times as loud.
Distance diminishes the effective dBA level reaching the ear. Thus, moderate auto traffic at a distance of 100 ft (30 m) rates about 50 dBA. To a driver with a car window open or a pedestrian on the sidewalk, the same traffic rates about 70 dBA; that is, it sounds 4 times louder.
At a distance of 2,000 ft (600 m), the noise of a jet takeoff reaches about 110 dBA — approximately the same as an automobile horn only 3 ft (1 m) away. b
Subjected to 45 dBA of noise, the average person cannot sleep. At 120 dBA the ear registers pain, but hearing damage begins at a much lower level, about 85 dBA.
The duration of the exposure is also important. There is evidence that among young Americans hearing sensitivity is decreasing year by year because of exposure to noise, including excessively amplified music.
Apart from hearing loss, such noise can cause lack of sleep, irritability, heartburn, indigestion, ulcers, high blood pressure, and possibly heart disease.
One burst of noise, as from a passing truck, is known to alter endocrine, neurological, and cardiovascular functions in many individuals; prolonged or frequent exposure to such noise tends to make the physiological disturbances chronic.
In addition, noise-induced stress creates severe tension in daily living and contributes to mental illness.¹
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