Some projects are no-brainers. The proposition: Replace a drilling rig’s diesel-generated power with power from an electrical grid, lowering emissions and costs.

When Hess engineers approached Vicky Jackson Nielsen, Hess’ director for drilling and completions in the Bakken, with that proposal, it didn’t take her long to agree.

Vicki Nielsen
Vicky Jackson Nielsen, Hess’ director for drilling and completions in the Bakken. (Source: Hess)

The switch presented an opportunity to improve operations and sustainability while playing a role in meeting some of Hess’ greenhouse-gas targets, Nielsen told Hart Energy.

The drilling and completions business in the Bakken is a small part of Hess’ overall operations and emissions sources, she said — but every reduction helps.

“When we realized that it would save us money, that was an additional opportunity, kind of a little bonus effect for us. I was in the camp of, ‘if it's even breakeven, I'm willing to do it,’” she said. “When somebody said, ‘but you'll actually save money doing it,’ I was definitely sold on the idea.”

Over five years, converting the four rigs Hess has operating in the Bakken from diesel to grid power is expected to reduce associated greenhouse-gas emissions by 50% and energy costs by nearly 70%.

Tapping the grid

James Hall
James Hall, senior director for the energy transition at Canrig, a division of Nabors. (Source: Nabors)

James Hall, senior director for energy transition at Canrig, a division of Nabors, told Hart Energy the company’s focus is on developing technology creating a path to net zero emissions drilling activity.

Along the way, a number of different products have been developed, including a “smart” power and engine management system, fuel additives, energy storage technologies and the PowerTAP Highline Power Transformer Module. The goal with PowerTAP, he said, is to replace diesel generators by making it possible to use electricity from the grid to power drilling operations.

Nabors collaborated with Hess on the initial roll out of PowerTAP to connect the rig to the electrical grid and switch between electrical power and diesel generator-power as needed.

Developing PowerTAP was not straightforward.

“The thing that we put the most amount of focus on is to have a solution that fits all the different markets. We don't run rigs in one part of the U.S. with only one grid. We connect to different utility grids” using different voltages throughout the country, he said.

And as Nabors rolls the technology out to other countries, PowerTAP has additional capabilities, such as frequency conversion to cope with mismatches of frequency, he said.

“A huge part of the development of PowerTAP was to make sure whatever we provide as a solution has no negative effects to the constant supply of power.”

Hall said that constant power supply comes down to being connected to a consistent, reliable grid. If the power does go down, PowerTAP has a transfer switch capability that brings the diesel generators online — a process that will soon be automated, he said.

The skid-mounted power transformer module connects the utility grid with the rig’s powerhouse and regulates highline power voltage to align with the rig voltage. (Source: Nabors)

The system also had to report on the actual amount of electricity used, he said.

Hess Bakken
X27 rig. (Source: Hess)

‘Sounds of silence’

Within five months of the proposal, Hess and Nabors had switched the power source to the first of four rigs Nabors was running for Hess in the Bakken, Nielsen said.

Bringing the project online in 2022 took planning and coordination, including contractual agreements with Nabors and lining up the necessary equipment.

Hess opted to pilot electric rig power with the X27 rig in the East Nesson area based on its access to a continuous power supply from Mountrail-Williams Electric Cooperative (MWEC), Nielsen said.

Nabors arranged for the transformer and the equipment needed to distribute power to every piece of equipment on the rig and installed its Canrig PowerTAP Highline Power Transformer Modules to access highline power.

Hess purchased a metering cabinet from MWEC, that was ultimately consigned to Nabors with the balance of the distribution equipment. MWEC installed the power to the wellsite and assisted with making the final connection to the electrical distribution equipment onsite.

“We needed to work with the power company to make sure that they could supply the amount of power that we needed,” Nielsen said.

That included procuring the transformers, the line, the medium voltage line and electricians qualified to work on that level of voltage since regular rig electricians are not qualified.

“So there was just a lot of coordination of our resources, Nabors’ engineering resources, field personnel, the electric company,”  Nielsen said.

She said operations run more efficiently on electricity for several reasons: generators don’t need to ramp up; engine maintenance no longer needs to be coordinated by operations; rig equipment ;is not constrained by power generation limitations; and the rig runs more efficiently and immediately responds to changing operational loads.

And on top of all that, another benefit: the sound of silence.

“It's significantly quieter. In fact, you can hear the pipe up in the derrick smacking against itself in a windy situation, and you could never hear that before on the ground. It is significantly quieter,” she said. Drilling supervisors on location initially found it “unnerving because it was so quiet.”

Using electricity did initially raise concerns around the continuity of power to supply rigs requiring 12,000 kW-hours of electricity daily.

“A big concern originally was the continuous power. Are we going to have enough continuous power? And then B, if we lose power, what do we then do?” Nielsen said.

The diesel generators that previously powered the rigs remain onsite for back-up purposes —when moving rigs or a storm disrupts power. Then a switchover to diesel can be done “within a reasonable amount of time that doesn’t disrupt the drilling operations,” she said.

Hess had to rely on those following a major snowstorm that essentially closed North Dakota for a month during the winter of 2022, Nielsen recalled.

And when rigs move, Hess’ well facilities team works with MWEC to have power ready for the rig prior to arrival. According to Hess, less than 10% of the time a rig may be required to use generator power — perhaps for a day or two upon arrival at a new drilling site to handle low-load activities while utility power is hooked up.

During the last day of drilling operations, the wellsite is shifted back to a generator so the utility infrastructure can be removed and relocated to the next location.

Hess operates about 465,000 net acres in the Bakken, where it holds about 2.2 Bboe in EUR and estimates about 1.7 Bboe has yet to be produced. (Source: Hess)

The pilot was successful enough that Hess decided to make the same switch on the other three Nabors rigs under contract to Hess, she said. Nabors X24 and X10 moved to line power in January 2023 and X28 following suit in April 2023.

In addition to the four rigs that Nabors contracted to Hess, Nabors has made PowerTAP available on 21 other rigs it operates. According to Nabors, field results from more than 20 PowerTAP modules deployed in the Lower 48 on Nabors and non-Nabors rigs show an initial average Scope 1 reduction that is the equivalent, per rig, of 20 metric tons per day of CO2.

Relying on electrical power for drilling in the Bakken is expected to help Hess meet its 2025 emissions reduction target of reducing operated greenhouse-gas emissions intensity and methane emissions intensity by 50% compared to its 2017 levels.

“It's been a very successful implementation for us. There's nothing that makes us think we need to go back the other direction and go back to diesel generators,” Nielsen said. “We saw all the benefits that we hope to see, which is not always the case when you introduce new technology.”