As part of the upgraded supply and services agreement, Prometheus said it would provide "additional LNG solutions" for Apache's new dual fuel and dedicated gas drilling rigs and for the hydraulic fracturing pumping engines used by Apache's oilfield service providers.

Prometheus' services will also include LNG supply, logistics and deliveries plus onsite LNG equipment for storage and regasification.

With costs even more important for tighter margin-facing unconventional operations, Apache praised Prometheus.

"We are evaluating all options for use of natural gas in all of our field applications, including field gas, compressed natural gas and LNG," Apache executive vice president and chief technology officer Mike Bahorich said.

"When you consider the total cost of ownership and the additional project and operational advantages, the evaluation looks very promising for all three fuel applications.

"Prometheus has done an excellent job for Apache thus far with LNG."

Prometheus is targeting more business with oil and gas companies that want to transition to gas-powered options to improve their environmental footprints and return on investment "from this age of natural gas revolution".

"We are excited to be partnering with Apache, a well-respected leader in the development of clean burning natural gas as a replacement for expensive diesel fuel in drilling rigs and fracturing fleets," Prometheus CEO Jim Aivalis said.