Natural Gas Generators Turn a Byproduct into an Asset on Oil Drilling Operations

What’s the difference between a diesel generator and natural gas generator for an oil drilling operation? About $700,000.

That’s the potential for fuel savings when using a natural gas generator designed to operate on wellhead gas — a common byproduct of oil and gas drilling — vs. a diesel unit. Wellhead natural gas is free when extracted as part of the oil drilling process, while the average cost of diesel fuel is $4 a gallon.

At an onshore oil drilling site, it’s not uncommon to operate around the clock and throughout the year. At $4 a gallon, 20 gallons an hour, 24 hours a day, 365 days a year — the cost of operating a 200-kVA diesel generator adds up to $700,800. Not to mention the cost of transporting the diesel fuel to the jobsite.

Using wellhead gas to power a natural gas generator is a fairly straightforward process for those familiar with the oil and gas industry. Minerals (i.e. oil, gas, etc.) extracted from the well are separated using onsite equipment. The natural gas captured through the process can be piped through a hose connected to the generator inlet port to power the generator.

Considering the significant reduction in fuel costs compared to a diesel unit, a natural gas generator seems like an obvious choice, but there are certain factors to consider when selecting a mobile generator.

Low Flow
There are times when wellhead natural gas may produce low or inconsistent flow that isn’t suitable for powering a generator, causing periodic losses in uptime or an inability to run a generator. In these instances, it’s essential for a natural gas generator to operate on an alternative fuel source. Doosan Portable Power natural gas generators are equipped with an automatic dual-fuel switch that allows the generator to operate on liquid propane from an external tank, ensuring continuous operation should natural gas lose pressure or quality. In addition to propane, Doosan natural gas generators can be connected to pipeline gas if available.

Telematics can help minimize the downtime associated with an unexpected machine shutdown by remotely monitoring machine performance and productivity. Not only does telematics provide a system alert when a generator experiences a malfunction, but it also improves support and speed of repair by delivering vital diagnostics. The information allows a technician to troubleshoot the possible cause of a malfunction before arriving onsite, eliminating multiple trips for appropriate parts or tools — and ultimately getting the machine back up and running faster.

Some advanced telematics systems warn of a potential problem before it causes enough damage to shut down a machine, such as water in a fuel line. Should an unexpected machine malfunction occur, telematics can also provide the exact position of a machine, so a service tech can more easily locate the generator for diagnostics. This geo-locating capability is an especially beneficial tool for machines used in remote areas, like those common to oil and gas operations.

Telematics are an optional add-on feature for many generator units; Doosan natural gas generators come standard-equipped with telematics.

Dirty Gas
Another factor when considering a natural gas generator is that wellhead gas often contains dust and debris — such as salt, sulfur and sand — that can impede the generator performance. Poor gas quality can de-rate the generator and in some cases cause machine failure, resulting in costly downtime. Doosan Portable Power natural gas-powered generators contain a patent-pending Onboard Fuel Scrubber System that removes debris and excess water from wellhead gas, ensuring generator performance.

Not Enough of a Good Thing
In addition to dirt and debris, the makeup of the wellhead gas can also affect generator performance. Because wellhead natural gas has not been purified through a refinery — like the natural gas used to power homes — it’s important to analyze a gas sample to know the percentages of methane, butane, propane, etc., and if the gas contains a high amount of sulfur, which can impact the performance of a generator. The higher the percentage of methane, the better the generator will operate.

Environmentally Friendly
Unlike its diesel-fuel counterparts, natural gas generators deliver ultimate fuel efficiency while meeting environmental regulations on emissions and containment. Natural gas is a cleaner burning fuel and emits lower levels of potentially harmful byproducts into the environment compared to other fossil fuels and diesel gas. The units also offer 100 percent containment, which eliminates the possibility of a costly spill. The other alternative to using wellhead gas to power an onsite generator is to “burn-off” the natural gas, a practice known as “flare gas” because of the visible flame that often accompanies the practice. So not only is using a natural gas generator a cost-saving and emissions-conscious option, it is also environmentally friendly.

A Place for Diesel
Natural gas-powered generators are designed to accommodate the exploration, site preparation and production common to the oil and gas market, and there are other jobs that require those same rugged, reliable features, including water well drilling, industrial plants and auxiliary or maintenance power applications in factory settings.

Even with all the benefits using wellhead natural gas is simply not an option for all jobs — and there is still a place for diesel-powered mobile generators. For jobs without access to natural gas, and those requiring reliable uptime and extended productivity, Tier 4 Final diesel generators are still the best option.

Natural gas generators can provide peace of mind and simplicity with specialized features designed to deliver high-performance and productivity in any oil and gas field in the world. The optimum fuel efficiency, ensured uptime, telematics monitoring and total containment of operating a natural gas generator — not to mention the potential $700,000 of cost savings — translates to better fleet management and a solid bottom line.

Wyatt Franks is the North American assistant product marketing manager for Doosan Portable Power, based in Statesville, N.C.