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Today’s oil business mantra involves “cash flow” and “ESG,” not particularly in that order. To that end, there is a small but growing awareness of the financial, operational and climate benefits of running frac jobs with electricity generated onsite by something other than high-carbon-footprint diesel.

Diesel does deliver more energy per unit than almost any other fuel, but its carbon footprint—and costs—are not confined to what’s burned onsite. Delivery trucks—also likely burning diesel—must deliver load after load to a typical frac site. These sites are usually at great distances from the fuel’s refining and distribution points.

In that light, more producers are looking to alternatives such as using site-produced natural gas to generate power for electric pumps in their frac jobs. Other options include fueling reciprocating pumps with blends of compressed natural gas (CNG) and diesel.

E–fracs, using produced gas, CNG/LNG or other fuels, constitute only about 10% of today’s activity. But their advantages lie in ESG benefits such as lower carbon emissions and, especially in the case of site-sourced natural gas, significant cost savings.

Options

While there are occasions where the established grid can power e-fracs, it is rarely a viable option. Usually there is not sufficient power available in remote oilfield sites. For this reason, the majority of sites at any stage from drilling to fracking to production, generate their own power in one manner or another. 

Gas Turbines

A major advantage for gas turbines is their fuel flexibility. They can run on field gas, CNG, LNG or a blend. Many sites run on produced gas, with CNG or LNG as a backup in case there is a temporary problem with the site gas.

Unlike reciprocating engines that require processed-quality gas, turbines can easily adapt to most of the vagaries of site gas with just a skid-mounted conditioner as a safety net. Site gas often contains unprocessed NGL that can raise the Btu level to 1,600, well beyond the about 1,000 Btu of CNG/LNG. High or low Btu from gas with significant loads of nitrogen or CO₂ are not a problem, within certain parameters.

Where savings really comes into play is by using the unprocessed field gas as a primary fuel source. The turbines have no problem burning wet, high Btu produced gas while still providing industry leading reliability.
 
Turbines can also produce more power in a smaller package than can reciprocating engines. In larger operations, this means less equipment and fewer personnel onsite, boosting safety while reducing operating costs.

If a producer has built out their powerline infrastructure for a multiwell pad, a gas turbine or bank of turbines can be installed in one place to power the entire grid for the duration. As each frac is completed, the frac fleet simply moves to the next well, ties into the overhead grid and resumes work.

After all fracs are complete, a smaller number of those same turbines can stay onsite to power lift systems and other equipment involved in production, still using plentiful field gas instead of needing truck after truck of diesel fuel.

Using a few high voltage generators on a grid is usually more reliable and cost-effective than scattering smaller generators across the grid, creating extra challenges for logistics such as maintenance, fueling and others. This also requires fewer personnel hours for these tasks, reducing payroll hours.

Power requirements of each frac job dictate the size and count of turbines, ranging from 15 MW to 30 MW or more. Larger turbines can generate up to 35 MW, medium turbines have a capacity of 17 MW. The smaller size 5 MW turbines are scalable—they can be paralleled for a 15 MW frac job.

These turbines further generate savings by being low maintenance compared to reciprocating engines. Turbines require only six to eight hours of maintenance per year, so the engine can be shut down for a borescope inspection.. They never need oil changes, because the lubricants are self-contained. They are rated at 99 percent mechanical uptime. 

Summary

Applying gas turbines to electric fracs checks a long list of boxes for new-era E&P companies, from cost savings to efficiency to greenhouse-gas (GHG) reductions and, most importantly, increased pumping hours. Fueling them with field gas adds the GHG benefit of eliminating diesel-powered site deliveries for diesel. Site gas also reduces operating costs even when considering that the gas could have instead been put into the sales line at today’s high price of $5 MMBtu.

And with more power available in smaller footprints, gas turbines offer safety and logistics benefits on site as well. 

Change, understandably, begins slowly. Thousands of fracs have been successfully done under the old ways for more than 10 years. But with so many technological advances flooding the oil and gas space, producers are becoming more open to adding e-fracs to their efficiency and ESG arsenal. It is impossible to ignore the cost savings, ESG benefits and increased pumping hours the e-frac fleets bring to the table.


Life Cycle Power provides turnkey mobile and custom power solutions to the energy industry.